Challenging Cranking No Start Diagnosis 1995 Suburban

1995 Chevu Suburban 5.7L towed to my house to diagnose and fix a cranking no start. Because it's a '95, my scantools are useless!
Also I find this "bypass" Ignition system is not something I am familiar with.

[@JohnDoesGarage]

I'm a lot older than you are and I was working on vehicles when there were no sensors and the ignition systems still had breaker points in them. I have changed countless ignition control modules on all makes and models because when they were first introduce they were prone to failure. At the beginning of the video the ICM was my first thought, only because of my experience working as a professional mechanic when they started introducing the electronic components that replaced the all mechanical technology. You proved yet again the FASTTEC method works every time. Thanks for the blast from the past.

[@hindflight]

Likewise with Chryslers of the era - the ECM "brain box" would go bad and / or voltage regulators all the time.

[@brenyz5013]

Yep they go bad all the time . But it was still funny when he said there is no way there is no crank sensor !!! He must be younger than we think we grew up cleaning points with dollar bills to get spark lol.

[@wyattoneable]

These type of videos (where we question our answers) are the best! So much to learn from our own experiences and inexperience's. Like Mike, this is the era of vehicles that I'm used to and have some experience. But I still learned a lot by watching and listening. Always a pleasure Matt.

[@SchrodingersBox]

Thanks as always!!! Yeah no doubt the guys familiar with these olds systems got a kick out of this hahahaha. No crank sensor- who knew??? You guys did lol.

[@HouseCallAutoRepair]

Funny how this hits us older wrenchers...I could fix carburetors, but didn't understand the "how" they metered the actually delivery. While I understand venturi function, I never gained enough knowledge to have a clue how to calculate the dynamics. At least todays stuff does a pretty good job of doing it for you... Until it doesn't. Regardless, the principles are always present ... What's MISSING. 👍

[@TheDisgruntledMechanic]

@@SchrodingersBox But you didn't know, so you questioned it and figured it out! That is what mechanics is all about! And you were confident enough to show that you did not know it and leave that in the video!

[@mtrltoolman]

Your diagnosing method is good, no matter how long it takes to find the cause of the problem. Keep it up!!!

[@sheerwillsurvival2064]

This is my years . Before I joined the army I was a lol MR goodwrench technician at a Chevrolet dealership. I was like this is my area . Great job Matt 👊🏻👍🏻 ICM

[@pamelavance648]

Honest efficient knowledgeable reliable service.. dang we need more mechanics like you 😊

[@ws2664]

And another thing, that tan wire with black tracer needs to be unplugged to set initial timing, if you follow that wire from the distributor to the computer it will have a connector, it's usually along the fire wall sometimes inside under the dash by the glove box so if you do replace the distributor, I know we all mark it best we can so we don't have to reset the timing but if something is wrong or the engine gets bumped accidently and you do have to use a timing light you have to find that wire and connector and unplug it, when your done timing it plug it back in and your done.

[@SchrodingersBox]

Great tip!!

[@ricktarded5943]

Thank you!!!

[@kurtdavis7588]

I know you're not a professional mechanic but you put in the effort to know the systems like it's how you make a living. My best friend surprisingly left his white collar job 7 years ago to do mechanic work because he swore it was more mentally engaging than people realized and that seems to be the case. He also told me a lot of folks don't realize how much information is on the computer in those old gm vehicles.

[@SchrodingersBox]

Yes I have talked to a tech school where they say they routinely have corporate white collar types that sign up for their programs because of exactly what you stated!!!

[@kurtdavis7588]

@@SchrodingersBox he sent me to your channel. Are you familiar with older cars,pre efi? He says those can be difficult in their own way. I've just been tinkering on stuff and him helping me out on weekends and it's just way more difficult than I thought it would be.

[@SchrodingersBox]

Hands down the older the car the simpler it is. There is no debate on that. If a 1967 Buick has no spark there are only maybe 2 or three things that can cause that and testing them takes 5 minutes. In a 2018 with no spark there are about a dozen things that can cause that and only 2 or 3 are “visible”. The other thing about an old car is you don’t even worry about emissions. You “tune it by ear” and pat yourself on the back at how it purrs. But on a newer car it will also purr like a kitten but that check engine light tells you it isn’t fixed.

[@kurtdavis7588]

@@SchrodingersBox I have no idea but my assumption was in line with you. He was working on a 2020 navigator and had all those trinkets and scope out dealing with a challenging problem. A older Oldsmobile pulled up and he turned it away after looking over it. He said those older cars can be harder to work on and make money. He said, things rusted, brittle, stripped, patched up multiple times and dealing with all that makes them harder to work on and make money. I would think I'd rather get the older cars too without as much technology to deal with

[@SchrodingersBox]

The technology is opportunity for money. Anyone can fix an older car so there is less marketability. But if you can diagnose and fix a CAN network then you will be the only person in your entire zip code that can do that. You can charge double if you wanted.

[@jamesreed7358]

Good video :) As a mechanic for 50 plus years I had to chuckle when you were looking for crank and cam sensor :) Good plan to replace all at the same time and avoid the same thing happening again !

[@brenyz5013]

Yea I was like what is he taking about but I didn’t realize how young he is lol

[@calholli]

Expectations... It's all about setting up proper expectations and then meeting or exceeding them. This is what makes a happy customer. I agree with you: lay out what fixes it-- and give the option for a more reliable upgrade by replacing the rest of it. indeed

[@Graham_Wideman]

Matt: "But but but, it has to have a crank sensor!" Distributors everywhere: "Ahem! What do you think we've been doing all these years!" Hahaha... good video and a bit of a chuckle at Matt's expense, but all in good fun! And of course Matt knows how old no-ECM cars work... it's just these "transition" vehicles that are a confusing hodge-podge of electronic and electro-mechanical.

[@warrenfromga9945]

Thank you for explaining the detail. I know it is tempting to "Just get it done" but for those of us trying to learn the science of it all you are the bomb.

[@SchrodingersBox]

Thanks my friend. Yes you are so right. The filming makes this take 3 times longer. But I always know you guys will call me out if I overlook something plus I know you are trying to learn it. Keeps me motivated!!

[@calholli]

You should be able to just replace the module alone for an ultra budget repair. They usually just get hot and burn out over time. I don't know how old this one is though--- if they can afford all new ignition, then it's good to send them off with more odds of avoiding a come back like that.. But if it were me doing it for myself, I always go for the ultra budget repair, simply because it doesn't cost me anything to fix then next thing that goes down again. Where as for a customer-- they would have to bring it back for more work- so leaning towards replacing the whole ignition makes more sense for sure. Bravo

[@alexismarcyting5340]

it does’nt seem you are challenged, you make everything look easy because of the fundamentals and principle has in your brain. Thank you for sharing!!!

[@SchrodingersBox]

Thanks my friend. You are very correct. The principles and fundamentals definitely help. It’s a matter of “how does this car apply them” more than “what the hell is going on”. For example- when I found the car doesn’t have a crank sensor- I know there still has to be some way the PCM sees the RPM. There has to be. It’s not going to be magic or some new physical concept. Something spinning on the engine is going to generate that RPM signal and It can only be the distributor if there are no cam and crank sensors. That’s what led me to the purple/white wire and then it’s game over because I understand the system now.

[@danieljurgill1681]

Cross fire and tuned port injection cars have been using this design since at least 82. Prior to that the HEI, was used with a vacuum advance. In 82 the advance was controlled by EST , electronic spark timing. The ICM has 2 sets of internal switches. One set acts to control the basic ignition grounding the primary, just like old time points. The other set switches when the engine goes above 400 rpm and the ECM sends out 5V to the tan/blk bypass ( set timing connector). It then allows the signal from the ECM to come into the ICM on the WHT wire and change the timing advance . The purple/wht wire is the signal generated by the pickup coil and amplified in the ICM. The purple /wht must get pulses to the ECM. If not the fuel pump will stop after 2 seconds and no injector pulse will be allowed. Code 12 means that there is no signal on the purple/wht. The EST white wire comes into the picture after 400 rpm, the signal from ppl/wht, most other sensors, AND the knock sensor. One way to partially check the pickup coil is to disconnect the set timing bypass line. If the engine runs the pickup coil is bad. When the pickup coil develops a low output it often is sufficient to run the car at base timing, but not enough to run when also powering the EST function. I was disappointed that you did not dive into the root cause, either the pickup coil or the ICM, but I understand you are doing this as a business for customers. You could still check on that old distributor, then you would know which of the parts you could use for a spare ! The tach reads off the primary circuit ground side wire....like you said, the first clue. Love your videos ! My 85 vette has been with me for 35 years.

[@danieljurgill1681]

If you got the paper clip out , you should have got a code 42..

[@SchrodingersBox]

Thanks for the additional info!!

[@fgoindarkg]

I'm having constant ICM problems due to corrosion on the terminals. Where do you disconnect the set timing bypass wire? Is it the brn/wht wire? Where is that, ECM. Where is that in my 89 g20?

[@danieljurgill1681]

@@fgoindarkg What is a G20 ? On a HEI ignition system the set timing connector is the only wire out of 4 ,that has a separate connector. On my car it is TAN /BLK .

[@ricktarded5943]

Thank you @danieljurgill1681 !!! Someone finally explained this in a technical way that puts all the pieces together.

[@bartscave]

Holding a weller soldering iron near (not even touching anything) the icm will mimic the cam sensor (pickup coil). It will spark the coil if the icm is good. In a no spark situation this is how you decide if the pickup coil or the icm is at fault. You have to try it to believe it. Usually the icm is the culprit and easily replaced without replacing distributor. Another thing that sometimes causes no spark is the distributor gear that is stripped, so check to see that it’s actually spinning.

[@SchrodingersBox]

Never heard of the soldering iron trick. Will have to try that!

[@bartscave]

@@SchrodingersBox I had to try it too. It didn’t sound plausible but it was actually the oem procedure.

[@ThunderbirdRocket]

Nice one ! Super helpful !

[@gilberthale7777]

I remember back when all engines in American automobiles ran their timing off the distributor with ignition points, and with early electronic ignition systems using distributor stators and reluctors (or similar equipment) triggering the electromagnetic flux of ignition coils to collapse.. The concept of having a crankshaft and/or camshaft position sensor with later computer controlled engines, with no involvement of the distributor other than to point high voltage discharge current to the appropriate spark plug, was totally alien to me. It was all but sacrilegious in a way. But, in time I got over that new fangled design and accepted it as a better solution as those crankshaft position sensors were not impacted adversely with timing chain stretch - about the only advantage I saw to it was the improvement with consistent timing accuracy being triggered by the actual device that needed to be timed. For the record I was not reveling in your initial confoundment. As soon as you announced the schematic had no crankshaft or camshaft timing sensor I knew what was going on. At least I hoped I was right. heh heh... In any event, I could see the cause for the confusion with the schematics. I appreciate your keeping that part of the video in place, as opposed to editing the vidwo in order to show you knew all along how the system worked. I know with the few videos I have produced I opted to leave in any retrenching in direction, rare though it may be. I far prefer to see the side of humanity when folks presenting these videos do like you did, and let videwers know it is okay if a person needs to dig a bit and learn something new or unfamiliar. It makes for a better learning experience. Kudos...

[@SchrodingersBox]

Thanks and indeed I left my confoundment in because if it wasn’t educational, it was at least entertaining to those familiar with the systems!

[@cwstout1]

Matt, you are the most entertaining technician on youtube, you should have your own TV show on Motor Trend. Great job.

[@warrenfromga9945]

NOOoooooo! Producers and bean counters would ruin it for me.

[@SchrodingersBox]

Thanks but I don’t think there enough of a market for a TV show for this material. Remember- 98% of people are bolt spinners. That’s why you will never ever ever see an oscilloscope on any car enthusiast show.

[@cfcasazza]

In the old days, we would have just replaced the ignition module inside the distributor. That way there is no chance of messing up the base timing.

[@SchrodingersBox]

Yes actually I did look at the ICM only. It turns out is actually cost $10 more than the whole distributor! I ran into this on a 1996 Honda a couple years ago too. It’s better to get the whole distributor. Reinstalling it did suck- took about 30 tries to get it lined up correctly lol.

[@shadetreec6013]

If you can let it sit for a while before pulling the distributor to let the little residual oil pressure bleed off the pump then the drive shaft won't turn on you. Then mark distributor location to engine, pull distributor straight up letting the rotor spin then mark it's position to the distributor body. It should fall right back in.

[@ws2664]

Another test you can do , since you have a scope , is to check the pick up by back probing the green and white wires on the module and crank the engine. the pick up will create a AC sine wave , which the module converts to a square wave on that purple and white wire to the computer, this will help, lets say the parts store has a module in stock but might have to order a distributor which may take to long or lets say the customer can't afford all those parts you want to put in, now the customer has a choice the module is cheaper and the labor is cheaper. Just a thought, that's what I tell my customers.

[@SchrodingersBox]

Ohhhhh what a great idea!!! I didn’t think of that!! Yeah that would have even more defined ICM vs distributor. Great thought!!

[@fredautos]

📌🤞

[@Mark.N]

And That's how you become a Destination. Well done..ending footnote made possible by the approach.

[@jimbeckettplay]

First off, I like and agree with your approach on most everything, and the scientific method applied correctly will always find the problem. That said, I can't help but snicker a little bit when I see you run into something you haven't seen before, like this system. I had a big belly laugh at your expense when you were questioning the diagram for not showing the crank sensor. Keep up the good work!

[@TheDisgruntledMechanic]

myself being an old relic I was also chuckling a bit at that but Matt powered through it!

[@randy1ization]

in these trucks, if the ignition isnt operating, it will not allow fuel either,. the root problem was likely a bad ground at the ignition module. rusty screws , poor contact, crusty wires, ect.. you can replace the ignition module seperately and save time and money,,, ONLY put a high quality distributor in these trucks,, nor amazon or ebay junk.,,. duralast gold, or ac delco.. ive been working on these trucks as a hobby for 10 years,, your doing the right thing by replacing the distributor id it has alot of miles on it,, they wear too,, replacing the distributor will eliminate ALOT of potential issues down the road..

[@AGuysGarage]

Good to see a video from you. Rhage73 here been watching you for a long time. A ton of good troubleshooting videos from you. Much appreciated thanks for posting. Ya older stuff .... nuff said.

[@SchrodingersBox]

Rhage against the machine is back!!! Great to see you again!! Brings back old time for me man!!!

[@randy1ization]

, ignition bypass is to set BASE timing,, if unplugged at the connector it takes the ECM ignition program out of the picture and only runs off the distributor and module.. the engine runs off the ignition module for just a couple seconds.

[@hassandallal6314]

Always on the point my man way to go and fenomenal diagnostic test and results

[@SchrodingersBox]

Thanks again, appreciate your support!!

[@dvdvno]

I had a 1989 Dodge Grand Caravan that had over 170,000 miles. It would not start at times and I figured it was the distributor. I eventually got rid of it before attempting to fix it. I do remember that when it wouldn't start, the tach would not budge while cranking.

[@Mr2004MCSS]

Nice diagnosis. After you verified there was no spark at the coil, I figured it was the ICM. I also knew that the ICM could be replaced separately from the distributor and was wondering why you were replacing the entire distributor. Luckily for OBD 1, I still have an old AutoXray 6000 scanner with enhanced data that still works very well. We still have a 92 and 94 Cavaliers that we drive so having an OBD 1 scanner is nice.

[@SchrodingersBox]

Yes I did realize the ICM is separate however I know from another video I have with a distributor that the ICM alone costs about as much as a new distributor assembly.

[@anthonymarsala5116]

I'm an old school chevy mechanic and don't think plugs wires coil need replacing if the ignition module is bad. In 1975 when chevy first used Cat converters and HEI ignition, they were towing in the new cars in droves because they wouldn't start. At first we were changing the ignition modules. Then after their engineers looked at the problem, they found out the phillips screws that were holding the module would not hold it correctly and replaced them with hex head screws. Plus added die electric grease to the back side of the module. And lastly changed the gap of the spark plugs from .080 to .045 saying the air gap was too much. (they replaced the plug to a different one since changing the gap that drastic would put the plug ground at a severe angle)

[@michaeldarrow6021]

Glad to see you're back at it 🥰

[@SchrodingersBox]

I never left lol!!!

[@gpc8337]

You proved that you have to be thorough. Thanks for the ruff ride on this one. Seems there is always a TOP TEN problems that repeat….but as show this one was not a TOP TEN ….I like the hard to find ones.

[@Rob-vl9ux]

You did great for not being familiar with a vehicle. I know early on that it was going to be the ignition control module because I've had to replace mine twice but the first time it took me awhile to diagnose it. Recently I had a issue where the truck started running rough and then it would be fine and then it will not start at all. I hooked up a remote start and could see the injectors pulse pulled spark plug and can see spark. Found top dead center and lined up marks on harmonic balancer then went to pull l distributor cap and found that it was loose because of a stripped screw repaired that and then was waiting on a jump because I had run my battery down. While I was waiting I ran across a video telling how to reset the computer so I decided to go ahead and do that. When I finally got a jump it would not start I knew I had some compression as putting my thumb over the number one spark plug to find top dead center at felt fine Truck was running fine before and the loose distributor cap explained all the symptoms that I was having. Now i am baffled but since during my diagnostics I had noticed that the spark plugs were overdue to be changed I started changing those then realized that I had reset the computer and it had gone back to the base settings when it had been making adjustments to the timing to account for the bigger Gap due to Worn spark plugs sure enough when I changed the plugs it started right up. I guess the moral of the story is do not change too many things at once if I had just tried it after repairing the distributor cap it would have run.

[@JoeMama-xt3nt]

Good informal video. I learned long ago from an old timer……you get what you inspect, not what you expect

[@aor3200]

Excellent diagnostics, once again.

[@randy1ization]

ABSOLUTELY RIGHT MAN, YOU ONLY HAVE ONE CHANCE TO FIX IT RIGHT THE FIRST TIME.,,,

[@mph5896]

Its a little unclear which wires you were scoping when checking at the ignition module. The purple/white was high ref heading back to the pcm. You mentioned then a PCM output, but not the color of that wire. The pcm output I see is a white that provides 5v to the ignition module. On your scope, there was no 5v if that was the wire you tapped into. Were you on the red/black? Also, you could further break down the diagnosis to see if its the pickup inside the distributor or the ignition module.

[@TheDisgruntledMechanic]

have done this before and seen vidoes on it but not with your detail! nice job Matt.

[@SchrodingersBox]

thanks Mike!! yeah this one had me swimming. figured the detail would be useful to anyone else running into this system.

[@TheDisgruntledMechanic]

@@SchrodingersBox yep my 1987 chevy pick up has it. also 1987 was 1st year for TBI on the chevy pick up.

[@SchrodingersBox]

You are like a freakin museum lol.

[@TheDisgruntledMechanic]

@@SchrodingersBox yeah I have 1993 Saturn too if you want to work on it!

[@wyattoneable]

@@TheDisgruntledMechanic I just missed ya!

[@electricaltyler5998]

Matts garage my wife got me that same sighn but says something different thanks for the video working on 94 gmc 1500 5.7 TBI crank no start new fuel filter, fuel pump, fuel pump relay, and fuse is good tested fuel pump it is good scratching head power is getting to pump going to replace fuel pump hanger tmw and hope its a bad connection the tubes are rusted and those stab ins had corrosion I got to get me a curtain rod lol

[@SchrodingersBox]

What evidence is there that the no start is a fuel issue?

[@VashthStampeede]

Good video. Entertaining to watch. Yes, us older mechanics were smiling through this one. There's no crank sensor because of the distributor and cap which is wired according to the firing order in the direction of rotation. There is no cam sensor necessary because those fuel injectors are constantly delivering metered fuel. The ICM tells the ECM to begin pulsing the fuel injectors when signal is received. No signal from the ICM means no injectors switched on. Since you resigned as a 2 percenter and brought out your parts cannon, I'm just poking fun, I'll say the ICM was the most likely culprit with the pickup coil in the distributor being the second possibility. You had no tach movement because it's derived from ignition coil ground. Probable scenario is spark plugs were neglected and the increased spark voltage demand sent a large enough back pulse to the ICM to take out the transistor. A new ICM and a fresh set of spark plugs would have been the fix. The integrity of the rest of the system could have been verified using your oscilloscope, like we used to do it in the good old days. I really do like you and the videos you provide, but watching this one is almost as good as watching a millineal trying to steal a car with a stick-shift.

[@SchrodingersBox]

Hahaha yes I left all the mistakes and frustrations in for that exact reason- so the guys familiar with this era can get a laugh on me!!

[@sebastian.rochag5]

deammm, you are a master! for 5 months i cant start my truck, and finally i resolve my problem!! thanks man!!!!

[@SchrodingersBox]

Congratulations!!

[@erikkirby1]

Just started the video but already thinking about GROUNDS!!!

[@SchrodingersBox]

Gosh dang it I keep forgetting to reference that hahahaha!!!!!!!! I even thought about it at one point and still forgot!!!

[@shaunfagan913]

Lol,we ain't getting any younger 😒 😁

[@rosewd2]

I have a 96 K1500 pickup. mine is obd2 and mpi spider injection, crank sensor and cam sensor in the distributor. The grounds going from the engine to the frame Tend to disintegrate causing all sorts of problems when they break as the battery grounds to the block, and only a bare braided cable grounds the block to the frame. Also I've had the hose between the fuel pump and the metal line inside the tank develop holes in it. So a fuel pressure check is a good idea.

[@billsmith2212]

I have 3 of those older GM's with the distributor . First , there is a magnetic pick up coil in the base of the distributor . Inspect the THIN wires from it . They can crack , etc. I will guess you may only need a ICM and not a complete distributor , unless there is a huge amount of miles in it . The ICM , Module , is a switch to collapse the magnetic field to make the coils spark . It also sends a signal to the PCM so the injectors pulse . I believe there is no timing control from the PCM under 400 RPM ,

[@billsmith2212]

I believe there is no timing control under 400 RPM from the PCM while the engine is cranking . The ICM takes care of this . Bottom line : if the module is bad , no spark or injector pulse . This distributor may also have one or two vent screens at the base . I would use brake clean on them . If all the other components look good and are not cooked , a module may get you fixed without spending hundreds on a distributor , coil , wires and plugs .

[@SchrodingersBox]

@billsmith2212 that’s correct. Exactly as you said is how it works.

[@nancymorales6420]

Your video was very helpful!!!! Thank you

[@SchrodingersBox]

You're so welcome!

[@hindflight]

The late 80's through the mid 90's were sometimes tricky - the complexity of electronic systems had begun but many ECU's didn't have the processing power for real time analysis. Not to mention the OBD1 connectors weren't standardized across makes! Solid diagnosis using the FASTTEC method.

[@northernpatriot9078]

Just as scanner danner taught during cranking icm is in charge during run the ecm takes over thank you sir this was a good study

[@SchrodingersBox]

I missed that one from him!! older video maybe?

[@northernpatriot9078]

Yes sir he goes in depth on GM bypass ignition this seems to be the predecessor

[@SchrodingersBox]

@northernpatriot9078 well damn. Would have helped if I saw that one hahahaha. I’ve seen tons of his videos. He’s the only car channel I watch regularly. Love that guy!!!

[@Dr.AymanKamar]

Well done Matt Old is gold

[@SchrodingersBox]

Love your new avatar!! Will be putting some time in on the book the next 2 weeks my friend and then let’s launch this thing!!!

[@m.b.smoshitoa8325]

I so much love your videos Matt, reason being they are real real. I noticed you don't cheat at all. If there's something that confuses you you don't erase it. I like that reality Your great follower Moshitoa 🇿🇦

[@SchrodingersBox]

Thanks my friend. Yes part of the value of the videos is seeing the learning process in action. I fully realize lots of mechanics out there would already know this vehicle has no crank sensor. I have no way of knowing that and neither do most DIY’s. That’s the value in keeping the content honest. It doesn’t help as much if I edit it all out to make it look like I am an expert.

[@DANNYN224]

Great diagnosis always use fast tech i was thinking distributor icm your diagnosing is good for young techs

[@randy1ization]

Usually a test light wont pick up injector pulses.. you would need a noid light.

[@bartsarton2212]

Hey Matt, Glad the new distributor (ICM) worked. One thing you didn't consider was that the mechanical connection (gears) between the camshaft and distributor had failed, resulting in the distributor's rotor not turning, therefore not sending a spark signal. Great video as always.

[@SchrodingersBox]

Good point. I actually did check that but didn’t show it in the video as the sound failed during that scene.

[@shawn2296]

plot twist customer had a control vehicle which he knew it had a bad distributor and asked to see “how honest” a “mechanic “ is he found you nailed it without selling parts and revealed to you he had a fleet as the true reward

[@SchrodingersBox]

Hahaha possible. Indeed before I started doing car stuff I used to do exactly that. I would know what’s wrong with the car and see what shop diagnosed it honestly, and they won my business.

[@shawn2296]

@@SchrodingersBox sad now a days we have to consider this just to find someone honest but throughly diagnosing something is hard to find i to find someone in orlando fl everyone is set on tryonostica

[@ivanesquivel2831]

@Schrodingers box any idea for a 2015 Nissan Vera note? Starts sometimes (when cold) scanner says (camshaft sensor P0101) online P0101 is an oxygen sensor. Replaced the sensor (crank no start) spray starter fluid (starts) once i shut it off won’t start back on. Replaced fuel pump, camshaft sensors, checked all fuses, checked some ground cables. On my way to change the injectors. DIY it’s worth it for me to say “it needed it anyway.

[@SchrodingersBox]

What data do you have?

[@Tman317]

Binge watching your videos, these are great. I love your methodology! But boy, do I have a good one for you. My 2011 Camaro V6. Started as a no crank. Found the ECM 15A fuse blown. Replaced, which allowed me to crank, even though it blew again. Blows anytime the door is opened (car wakes up). ECM fuse is powered by Powertrain Relay. Benchbtested, that's fine. Harness from fuse to ECM tested good (jumped load side of relay with harness disconnected), no short to ground. Stumped! Wish I could send it to you!

[@SchrodingersBox]

Thanks for watching. Pretty clear you just have a short on the ECM power feed. Disconnect it and use a test light to look for an intermittent ground.

[@Tman317]

@SchrodingersBox Hey thanks for the reply! Yea I did just that. Disconnected the harness to the ECM and tested from fuse (harness side) to pin in harness. All good, no ground. ??

[@SchrodingersBox]

Yes becauase its intermittent I would expect that. You'll have to wiggle wires and harnesses to try to create the ground and that will narrow down where issue is. An ECM fuse will blow with any fuel injection or ignition shorts so keep that in mind- it may even be a coil or fuel injector itself! I have video of this exact issue on my website- wiggling the harness blew the fuse right on camera- you could see it, and of course lit my test light as well

[@Tman317]

@SchrodingersBox Great, going to look for the video now. Mine issue isn't intermittent. No crank if the fuse is blown. If I replace the fuse, it'll crank, no start (fuse blows immediately) until car goes to sleep. Then no more crank again. Scares me that it could be injection or ignition, seems like a million paths to take to find the issue!

[@Tman317]

Btw, may have found your video, the Lexus? My wiring schematic doesn't show any fuel or ignition components on this circuit. Just 3 wires from fuse (it splits 1->3) to ECM pins...that's it. Could it be being backfed somehow, that wouldn't make sense to me?

[@carlodonnell146]

Matt is a comedian as well as an auto tech.

[@lionellambert9456]

The Ignition module was in the distributor. RPM have controlled by the distributor. Spark is controlled by the coil and the road account in the distributor.

[@carnivorebear6582]

Sure there are people who have used a scantool and still think it's magic box that tells you whats wrong. They just haven't used a scantool *properly*. I'm almost certain you've fixed many cars from "professional" shops that just see a code as a guide as to what ammunition to load in the parts cannon. It needed it anyway!

[@SchrodingersBox]

Oh yeah- I have about 3 dozen videos where I follow up after a shop couldn’t fix it. In fact had another one just today.

[@calholli]

I would say: Timing mechanical, Timing ignition (like you said). but also: Timing INJECTORS. Some cars will have ignition timing from a distributor and still have injector timing from a crank sensor, etc. So: Timing Timing Timing... definitely all a required necessity. :)

[@carnivorebear6582]

To be fair, that problem just falls under F for fuel. Just because you can start the car with an additional fuel source in the intake doesn't mean you've solved the root problem, you've just narrowed it down to an issue with fuel delivery, which could be caused by a large number of possible things. Mismatched (but still happening) fuel injection timing relative to ignition timing, apart from in direct injected systems (which all have purely PCM driven ignition/fuel timing anyway), I would imagine cannot result in a no start condition. Running poorly with a wandering idle rpm sure, but there's still ultimately a matched amount of air/fuel going through the intake, just poorly mixed (moreso in port injection scenario), which by my guess would cause the percieved A/F ratio to read lean, until enough fuel builds up in the intake to have it too rich, and then PCM overcompensates repeating the cycle - essentially an exaggerated version of what cars with oxygen sensors already do. Tomorrow morning I'll swap the injector connections on my port injected car, hookup the scan tool, and test that theory!

[@carnivorebear6582]

Just tested on my port injected inline 4 swapping injector connectors 1/2 and 3/4 - engine still starts right up, if I didn't know I swapped the connections myself I wouldn't even know. Idles great and runs all the way to WOT great too, both free revving and under load. Looking at the scantool it seems the O2 sensor oscillations are maybe a bit longer in duration but that could be a sampling error in how often my scantool can receive data. So I think it's fair to say, for port/throttle body injected systems, fuel timing relative to ignition/cam/crank isn't of great importance, especially in a no start situation. Edit: after further testing the oscillation frequency of O2 sensor is indeed lower, and at idle skews towards lean. There is also some lag/slight roughness between sharp throttle transitions (both on or off throttle). But even still, the car is more than drivable.

[@docnele]

Worked on my girlfriend's old Peugeot, and IIRC it had inductive type "pulse generator" for the PCU (hence no coil involved in generating it)in the distributor. It would also make spark independently i.e. only pulse for the monopoint system was driven with ECU. The system you have there is more sleek, it bypasses the signal to-from ECU on crank and when RPM get to idle value ECU probably moves it in request for advance/ retard of ignition based on parameters. BTW, it was ECU that was faulty in her case, in the way it drove the mechanic (who changed her engine head) crazy (the engine stopped intermittently). He didn't know it is a separate system, returned the car when it was runing with a sore note that it is "junk". I got a break when I noticed that "check engine" light ceased to work on contact when engine ceased to run (it is directly connected to ECU, of course), and I checked return pulse (that didn't exist). I ordered a second-hand, inexpensive ECU (and got NOS in the box from 1990!). Runs well, passes MOT (European).

[@Epro95]

When my Camaro still had an optispark and the original PCM, I had a red devil river OBD1 cable I used for scanning. Probably not worth it for you?

[@SchrodingersBox]

Hahaha I remember the optispark!! My first trans am had one. At that time I hadn’t even started working in cars yet so I am actually not familiar with any OBD1 tools at all- expect maybe a paper clip to jump the terminals to flash the CEL!!

[@JASSJOTCHEEMA0060]

Hey sir! My truck is in Brampton, Ontario, Canada. Please solve my problem. It will be 2 years since my truck brake down. Tell me what to do. What can be the problem? It started by total body open the spraying, without spraying, it didn't start, speed up from 70 & 80 on the highway, it didn't pack

[@ivanavila322]

I have a 2007 chevy tahoe giving me p0335,p0336. The only reason why i quetion it is because i have a slow turn/ slow crank. Will a bad ckp sensor cause a slow crank or does it sound more like a voltage issue?

[@SchrodingersBox]

What is your signal voltage on the sensor showing?

[@shaunfagan913]

Awsome job

[@kennypool]

" they blinded me with science"

[@ricktarded5943]

If it still works, then why replace it at 200 times the cost. I average about 750K miles out of these 88-94 Chevy/GMC trucks. Routine oil changes and a yearly transmission service goes a long way. What killed these trucks? Below is a list of the most common issues I have experienced in no particular order. Hope this helps you. 1) ICM's 2) Pickup coils 3) Temp sensor for computer (on top of the engine next to thermostat) 4) Thermostat 5) Transmissions lacking an auxiliary cooler 6) Not greasing or replacing worn door hinges in time and getting the "GM door sag" 7) AC's went out and vent door actuators failing 8) Seat cushions and frame wires rusting away (b/c ac failed and your sweaty butt rusted the springs and wires) 9) Rodents in the harness 10) Plastic Radiators lasted maybe 20 years 11) Knuckleheads butchering the wiring harness 12) Steering components wearing out making the truck drive like Ray Charles is at the helm 13) Ball joints (Fords would squeak and give you a heads-up prior to failing. GM...not so much. They would just go around 200K miles. Surprise!) 14) Using cheap lightweight oil in the engine and knockoff filters 15) Timing chain replacement every 200K - 230K 16) Brake hose failure after 25 years of service & Brake lines rusting 17) Frames would rust if in saltier climates without any coatings 18) Fuel lines from filter to TBI would leak at compression joints (believe it or not!) 19) Oil pressure sensor failure (On the back of block under distributor. If they failed it will kill power to the fuel pump) 20) Tilt steering column screws would come loose (Easy fix if you know what to do) 21) Broken axle parts from lack of fluid changes 22) Seals on front of transfer case would dry rot after 25 years, allowing trans fluid to fill the T-case while dry pumping trans (Yikes) 23) Servo on side of trans would wear causing loss of 2nd or 3rd gear 24) Sun shell's in transmissions were weak from factory 25) Flywheels would crack 26) Wrong antifreeze!!! Use DexCool only with Distilled water. Trust me or they will rust out from the inside. 27) Idle air valves will fail 28) TPS would wear and not hold constant speeds 29) Four wheel drive solenoid failure (Located on the top of front diff) 30) Heater hose connection failure on the back of the block Any of these events would occur and you could grab them for $500-$1000 on average. Those days are gone. Even junkers are going for jiraffe nutz now. So glad I stocked up on junkers years ago. Every time I saw one for sale cheap and was ahead on child support, I would go kick the tires and usually drag 'em home with a title in hand. I should be driving one of these until I leave this world.

[@pamelavance648]

Pre scan years cold start Manual transmission Strong crank no start Clutch in gas pedal down car starts let up on pedal and keep idle at 1000 rpm idle and warm for 5 minutes .. good to go Please recommendations where to start 😮😮😊

[@davidessien5465]

Great video sir

[@SchrodingersBox]

Thanks David. Always good to see you on the channel!

[@vusiematwa1233]

Hi Matt. Please help. My car does crank and every sensor is good according to the scanner, but yet there's no spark. What could be the problem.... it's a corsaD z14 XEP engen

[@SchrodingersBox]

What are your coil reference, signal and ground voltage showing?

[@fgoindarkg]

Tbi icm causes me constant problems. They aren't coating the terminals with anti corrosion metals anymore. BWD will fail in just a few months. The installation instructions advise to sand them every time they fail.

[@GearheadRob319]

getting the hood open was half the battle. lol

[@markchidester6239]

Adding the RPM signal, are you using battery voltage or the 5 volt signal voltage? Also, how are you able to determine which voltage is needed? Thanks Matt, awesome video as usual!

[@SchrodingersBox]

I am using battery voltage BUT at only 250ma.

[@JohnTaylor-aftrwjt]

It has a ignition control module

[@DillysADV]

I wish there was a time traveling way to tell you something while you are recording... In those older GM hoods you bump the front passenger corner of the hood (nowhere else works as consistently) and it releases to the safety latch.. they all do that to some level.

[@HouseCallAutoRepair]

Unless you're a dealer tech with a lot of experience, or almost every vehicle is a learning experience! Research is key on every job! Learn from others and develop a sense of what you're doing.

[@SchrodingersBox]

totally agree!! even after 10 years, almost every car I see is a new experience.

[@kenkellogg1752]

Got a call from a friend a week ago who's '95 Silverado died while driving. Had it towed home. He figures it's the fuel pump. I say "Can you hear it buzz?" "Yep" So it's not the fuel pump but it's probably the ignition module. He saz: "Maybe the filter is plugged" (Not likely) I tell him to find a spare spark plug and check for spark. He buys a new coil instead. Still no start. Me: "Did you check for spark yet?" Him: "Nope" Now he wants me to buy a IM and drive 20 miles to install it. Aw C**p! Probably had a spare IM in the garage from my old '91 S-10 but recently junked it after 300K miles & tossed out all the extra ignition parts, wires, sensors, and stuff I had collected over the years... Update: I paid $65 for the IM and made 35 bucks today

[@djartmakingmusic8677]

Matt all 1995 vehical have module inside the distributer to replace. That all .

[@nestorroman2694]

Excellent information Sir! I have a similar issue with mine 99 suburban code P1351 .icm replaced it with a AM no luck. I have fuel pressure and spark at the plugs n coil. New distributor cap/rotor battery,starter. Its weird sometimes it would run with cylinder 3 unplugged. Please help i. Did partsnostic on it.😢

[@SchrodingersBox]

What data do you have?

[@nestorroman2694]

@@SchrodingersBox I'm a diyer I don't have any data Sir.

[@SchrodingersBox]

Why would that be a reason? I’m a DIY too. You don’t need to be a professional to get basic data!

[@JASSJOTCHEEMA0060]

Hey sir please my help .2011 chevrolet silverado owner manual pickup truck spray in totalbody and start what could be the problem after 80 kilometres the race does not work

[@SchrodingersBox]

Sorry but I don’t understand the question. Sounds like fuel maybe sprays in throttle body but then car dies after 80Km??

[@sheerwillsurvival2064]

I was yelling put a pair of vise grips on that curtain rod. I’ve been donged to many times

[@DarrellBraunsLongThumbNail]

It's always ignition on GMs, lol. I'm looking at you HEI module😁

[@scraiga66]

Did you set the timing?

[@SchrodingersBox]

Yes I did. It runs like a dream even with 260K miles or whatever it had.

[@randomugliness1238]

Well.. I definitely kept saying "No crank sensor" but I only know that because I have a 93 k2500 and I had to learn the system to diagnose a no start!!

[@ws2664]

One more thing, you want to check the new distributor before you put it in to make sure it works, it would suck if you put it in and it's defective and you have to do it again, just plug the connectors on, the distributor needs to be grounded so make a jumper wire with alligator clips and ground it on the engine and dist housing and with the key on spin the dist gear and it should spark, I check all my dist that way so unless a customer brings me a defective or used dist I only get paid once to do that job.

[@SchrodingersBox]

Good idea!

[@ws2664]

Sorry for the 3 parter my brain doesn't work as fast as it used to.@@SchrodingersBox

[@ulfbjornson4930]

I think Amazon sells a converter cord for OBD1 to OBD2 for like 20 bucks

[@davevega4114]

Hello sir. New subscriber here from the Philippines. My Suzuki jimny suddenly dies and start when it's cold. I check and there's no spark I change the crank sensor and still don't start. What could it be? Is the ignition coil bad or the ECU. Because there's a 12volt power from the crankshaft wire, there's a continuity in the negative and it send power to the signal wire. By the way I test the coil and the resistance is .99 and .97. Suzuki jimny has 2coils each coil have 2 high tension wires.

[@SchrodingersBox]

What is the voltage output from the crank sensor showing?

[@davevega4114]

@@SchrodingersBox Blue black 11.59v, green red 5.3v, red black 11.68v. It makes me confuse because all the videos I watched. all the positive wire only produce 5vlts.

[@SchrodingersBox]

I need the running output SIGNAL voltage. That’s all.

[@davevega4114]

@@SchrodingersBox the green red puts out .32 v from 5.3v I tried to direct the coil and it produce electricity. Do you have Facebook sir? So that I can send you a picture.

[@SchrodingersBox]

Which on is the green red? Is that signal?

[@sheerwillsurvival2064]

Waiting on that book 🙀

[@SchrodingersBox]

Gonna work on a bunch over the next 2 weeks and get it ready. It looks totally different now. Lots of explanations!!

[@sheerwillsurvival2064]

@@SchrodingersBox fantastic can’t wait your a thorough teacher 👍🏻

[@xbreadwinner10x91]

So what if I’m getting no fuel? I changed the ignition module and still no fuel.

[@xbreadwinner10x91]

I’m getting spark though

[@SchrodingersBox]

Check the voltage drop on the fuel pump.

[@ImReelySuqi]

I have only set one engine on fire with starting fluid lol. Put it out luckily

[@Lou-eye]

Distributor takes the place of camshaft position sensors

[@SchrodingersBox]

technically it takes place of crankshaft and camshaft positions sensors. essentially it’s just the camshaft position sensor- indirectly.

[@jimmyfiggs6293]

Do you sew your own curtains too?

[@SchrodingersBox]

Hahahahahaha. Definitely worse at sewing by far!!!!!!

[@sanjeewaperera6950]

Hats off to you Matt; it's rare for KZbinrs to acknowledge something they don't know on the channel. Saying 'I didn't know'. DIY, like us, always makes mistakes and learns as we go. Thank you for making it real for us instead of showing that I know it all. I recently did a P0300 diagnostic, and it was challenging. But you make all your videos easy because you approach the task logically.

[@SchrodingersBox]

thanks my friend. I always film it as I go through- mistakes and all. Yes this one totally caught me off guard. I could have edited it to make myself look like a genius know-it-all but that’s not what this channel is about. It’s not about how these systems work- it’s about how to learn how these systems work. Huge difference.

[@jum5238]

Fuel pressure low disables spark. Look at fuel pressure not being sustained. (can't remember the part name - fuel pressure regulator? or fuel pump weak. Didn't see the fuel pressure being tested (early in the video right now))

[@SchrodingersBox]

I have never heard of a system where low fuel pressure disables spark. how does that happen? I have heard of fuel being stopped at a single cylinder on a misfire for that cylinder which is beneficial for obvious reasons, but I can’t think of any reason or function to disabling spark on low fuel pressure. how would this truck even “know” there is low fuel pressure?

[@bdi11000]

Leanmissfire or no good fire?

[@stephendavidcavuoti6548]

Dose anyone know how I change out the speedometer from cutting off at 100 miles a hr I buying new Gauge and putting a high performance stuff on it and I did this on my 2990 dodge Daytona but GM is different and before anyone say why would you want to go over 100 miles a Hr well I want to take to commerce dragstrip and see how fast of a quarter-mile I can lay down.

[@charlesgould8436]

Put a heavy pry bar under the hood, hanging out, while you pull the latch.

[@DuaneDonaldson]

You forgot to unplug the injectors to prevent a start and see if the TACH moves on this vehicle on a no start with good spark, thanks for the case study on an old GM ICM DIZZY.

[@daftnord4957]

Is it good if the tach needle jumps up when cranking?

[@SchrodingersBox]

It depends what you are looking for.

[@DuaneDonaldson]

Possible Scenario: Looking to create a list of vehicles in our private libraries that the TACH normally moves during cranking on a No Start, if it does not move then we can narrow down our diagnosis. If it is not designed to move as many late model cars, then we have that on our list and we do not need to pay attention to that. If the TACH is supposed to move but it did not early in a video, then we are looking for TACH movement after the repair and in order to catch that before a crank and quick start, it may be needed to prevent the start such as pulling a fuel pump fuse or relay to verify proper operation as proof since the non working TACH was one of our problems. YES, if the engine now starts and the TACH works, good enough, but that is not the same test. YES, I am anal, the original test was Crank No Start No Tach, I want a Crank No Start Good Tach as the same scenario scientific test, and be sure to annotate this vehicle in my database as such. Thank you for all your videos.@@SchrodingersBox

[@joeblow6786]

Chevy suburban... Does that mean you get left in the less than urban area because you're broke down? Oops, where'd my gas go?

[@SchrodingersBox]

Hahahahahaha!!! Around here you know you are in a sub-urban area when you start your car and find the catalytic converter was stolen lol.

[@northernpatriot9078]

Is this a GM bypass ignition

[@SchrodingersBox]

yes it is. I didn’t know what that even meant until I looked it up lol.

[@Flyingspann3r]

Hmmmm Matt, have you tested the coil primary or secondary resistance? The plug wire resistance and rotor arm resistance?? Or are you just firing that parts cannon like you slag the mechanics in your area off about. Jeez man why replace it if it has the correct resistances…. Hey why not replace the wiring loom too. Showing your inexperience on this one.

[@SchrodingersBox]

You make no sense at all. Why on earth would I test the coil when there is no output signal AND also I showed the coil generated spark. Let me repeat that- when I gave a ground control to the coil- it generated spark. So why on earth would you ask if I tested the primary? Can you explain that? Showing your inexperience here pretty bad there my friend. Pretty bad. Also how did I fire the parts cannon? I properly determined the ICM on the distributor failed. What other parts did I change? Name one part I changed that wasn’t necessary. Also why on earth would I replace the wiring loom when the PCM received and sent a signal that I input? Can you explain your logic there? Why would you change a wiring loom that clearly is in tact? Please explain logically. You make zero sense. Until then, I can only assume you simply don’t understand what happened here.

[@Flyingspann3r]

@@SchrodingersBox Hi, I was poking a little fun at you Matt, I’ve seen all your videos and this is the only one which surprised me. You are clearly an intelligent guy and you say yourself you tested the ignition coil and it worked. I was questioning, WHY change a working coil? FOLLOWING YOUR DIAGNOSIS REPAIR. I only change parts IF they have failed. You didn’t show yourself testing the primary and secondary resistance with a meter which is how manufacturers deem if the coil is bad, not by firing it off and seeing if it is capable of generating a spark. That is what I was questioning. Had you demonstrated the coil resistance results were outside the manufacturers specification BUT the coil still sparked, THEN I would have expected you to advise it’s replacement, with solid results based evidence. So my point is you fired the cannon AFTER the repair. Parts cannon 1) The perfectly working coil Parts Cannon 2) The ignition leads rotor and cap. You didn’t mention it had a misfire too 😉. These parts (unless tested to be outside the manufacturers spec) don’t actually need replacing. Referring to one of your videos which was quite funny( think it was the valve clearance job (lash) where you fixed the poor running by adjusting the clearances correctly, “well it may as well have them so let’s fit it anyway” I think was your line when slagging off the other shops, and rightly so. I took it that you assumed as it sparked it was fine. But let’s recommend to the customer to replace it anyway. A high resistive coil winding would stress the ignition module resulting in its early demise. But I didn’t see you check it against manufacturers specs. The logic to replace the loom was tongue in cheek. I know you wouldn’t replace it as there is nothing wrong with it…..But there is nothing wrong with the coil either, so why recommend replacing it? Over to you my friend, I look forward to your witty retort.

[@jamesprice6381]

im at 29:08, but im bettg its just the ignition module, changed @ least a 1/2 dozen in my ownership of a 78/85 TA and a 82 Camaro RS....my cheap 2c NEVER had ta change the distributor, nor plugs n wires,,,,,

[@user-vf3qe5xh6p]

HELP!!! I have same problem changed coil cap and rotor ICM still no spark now what? '94 suburban

[@SchrodingersBox]

What was your data that showed those parts were defective?

[@user-vf3qe5xh6p]

knew I had no crank sensor went to those parts obviously blind checked fuses first all those parts were original with 125,000 miles@@SchrodingersBoxhad no spark at coil or dist

[@SchrodingersBox]

Ok what data do you have though? I need something to go on.

[@user-vf3qe5xh6p]

I don't know what to tell you I still have no spark at coil or dist@@SchrodingersBoxdo I need to check volt on pink wire from switch to coil

[@SchrodingersBox]

Bypass then reference to the signal- see if the coil sparks. That would be the easiest test.

[@joeblow6786]

Matt, you're not a monster... Stop drinking monsters.

[@SchrodingersBox]

Hahahaha. Man I literally drink 2 or even 4 of those every single day.

[@joeblow6786]

​@@SchrodingersBox Matt, you're in medicine and should know better about the hazards of imbibing such things... Not that I don't love your videos.

[@SchrodingersBox]

Oh I recognize it. Believe me.