1988-95 GM Truck Ignition Systems

[@robertwilson4400]

10 years after you made this video, you're still spreading knowledge can't thank you enough for the last piece of my electrical puzzle. I appreciate you so very much.

[@crystalloduca8952]

Mannnnn you're a lifesaver. 800 in towing, 3 sets of plug wires later i appreciate this.

[@jamalcole1985]

Try gettng aaa roadside. 5 free tows every year

[@bobbyevers4348]

This worked! Purchased a truck with “no spark” 30 second fix!! Thank you!

[@jessehouston1694]

(95 1500 tbi) when all else fails, check the tach wire at the coil for ground.. If it has constant ground, a quick fix to get ya rolling is to clip it. The coil is signaled by ecm through the other white wire found in the second connector on the coil and these 2 splice into pine another inside the coil. The tach wire is finding a ground (i haven't began my search for it so ill try to get back here with an update) and that ground is trying to energize the coil anytime you hit the key and with enough time burns up the coil.. So if clip the wire orfix the ground, but still no spark.. Test your coil that you've likely just replaced or had replaced.. Hope this is helpful to someone nonethless

[@559Obsalex]

hi i had replaced the clips that go to the distributor.my truck would start with starter fluid but now it doesn’t can it be the coil?

[@jpartieda]

​@@559Obsalexsame here with my caprice. How did you resolve it?

[@thaddbrailsord1391]

So my issue is the tachometer wire, how did you fix the issue permanently. I would love have operating tachometer as well lol

[@TheHerbcavanaugh]

What's up everybody, I have a 95 Silverado. Kinda had the same problem, I put a towing cam in it this past summer and the computer went nuts trying to figure out what to do. I racked my brain for a week or so till I watched this video. All I had to do was unhook that single wire plug( 95 is under the dash on passenger side) and leave it unhooked set my timing and let the icm do the job. Runs like a champ

[@farmboy30117]

Awesome! Glad it helped :)

[@rontezclay5775]

How did you set the timing

[@clarencebrady6028]

So u unhooked the ICM witch is the PCM correct.... And u left it unplugged

[@LesDeplorables]

Wow! You just pointed out what should have been obvious to me! I forgot all about the timing wire bypassing the computer. This will tell me right away what my problem is

[@feltongailey8987]

Thank you brother. Can't wait for it to get daylight so I can check this. Replaced my head gaskets and hasn't started since. No spark.

[@farmboy30117]

This could also be caused by a bad pickup coil in the distributor. I believe autozone can test the ICM but don’t buy one there. Get it from a higher quality supplier like NAPA.

[@readplanet23]

Thank You so much sir. I appreciate learning auto mechanics from people who can explain in a common sense manner. Have A Great Day! 🛻🚤🏖️

[@farmboy30117]

Thanks, you too!

[@davekurtz321]

Agreed just went through 20 minutes of U-Tube videos Looking 👀 for the Wiring Diagram on A 1990 Chevy TBI EFI and lots of CLICK BATE ) but you have the BEST information ℹ️

[@grad0n]

Thanks man. My buddy’s 93 k1500 4.3 crank, no start was due to the ignition control module.

[@farmboy30117]

Yeah, that's pretty common. Glad it helped!

[@erikjohnson4628]

@@farmboy30117 every morning i have no spark and have to replace my pickup coil. Any idea on what to test

[@charlesmartin7347]

I am so grateful that you made this video. God bless you and your Family

[@farmboy30117]

Thanks Charles! I'm glad it helped!

[@evlmpyr]

@@farmboy30117 I could use help on same issue same engine.

[@ronaldlehmann6935]

Very good information- you made it easy to understand- thank you -God Bless

[@donaldmayor6791]

I have a 1991 k1500 5.7 did a complete tune up except coil, ran great for 100 miles, now experiencing a flat out no power situation, runs rough idle and can not pull a hill or gain speed at all except over time. I can put my foot into it and sometimes it will act normal until I take my foot out of it but than it acts like not running in all cylinders. Oh yes revolution the throttle body as well thanks Don

[@earnestharvey2389]

I have a 1993 GMC 350 TBI that has fire to the coil and to where the coil wire plug’s in to the distributor cap but it is not going through the plug wires what could be the problem with it I have put everything new in the distributor and coil area

[@randywl8925]

Great idea for me to try. Im having an erratic tachometer and severe engine miss in my 88 4.3. It will only run for a second or two, then die. I had to get towed home last night. Pickup coil and module have been replaced within the past year and so has TPS, IAC, MAP. Im suspecting knock sensor or Spark Control Module. Thanks for reminding me about the little brown wire. 👍

[@Cornfed_Off-road]

Finally someone showing stuff on a 454!

[@Cornfed_Off-road]

And yes this ain't a 454 but it's the same, and helped me figure out the issue on my 454

[@workingshlub8861]

i believe if you crank it and have fuel pressure out the injectors the pickup coil in the distributor is good.....went thru this on my 92 astro....thought i had bad coil but it was the ignition control module that was junk...the module sends a signal back to the coil to spark so dont assume its bad coil right away..

[@nevamind3334]

Thank you a million times over for taking the time to make this video, I truly appreciate it, you have helped me out. Great video.

[@farmboy30117]

Thanks, I'm glad it helped!

[@mikeanderson1994]

farmboy30117 what if the car runs ok but i keept that black / tan wire unpluged what will happe ? thanks man hope u replay to me

[@marcoo7239]

farmboy30117 what if no spark still after distributor changed .igintion module. The pink wire is getting no power whatsoever

[@stephanieroden6634]

My husband has 98 Sierra he has changed everything,hoping this is his problem...will turn over but won't fire...we had no clue about an ecm,until this web search,hes outside ride now hunting down that black tan wire,trying to do what you said for retiming... praying it works..thanks alot for the video

[@jaiden0115ify]

@@mikeanderson1994lol lll

[@davidcantrell64]

Thanks for this I just had to put new coil connectors on where someone had cut them off my 87 v20 and had a old school coil on it so I put it back factory.

[@alarthofer3595]

Good advice,.... i have a 93Sierra that never stalls but often will not start do to no spark...then one day when it feels like it she'll start ! Should of never gone away from good ole points !

[@farmboy30117]

Haha, well I do agree that the ICM is a finicky module and it does not like heat at all. Don't buy a cheap one either or it will not last long. I doubt OEM modules even exist nowadays though :(

[@ivanm4560]

This video is pure gold thank you!

[@Kevin-xm6bv]

Your video was very helpful, well displayed. Thank you.

[@farmboy30117]

I'm glad it helped!

[@topspeeddaily7179]

Very good job help me out a lot

[@cravinbob]

The coil failure will keep fuel from pumping also so no spark-no fuel will occur.

[@waxwarriorde4648]

Mine has spark but no pump on fuwl

[@hankbridges5055]

Get a Actron CP9690 code tester. It checks live, record, graphing, emissions readiness test, oxygen sensor tests, ABS, SRS, and MORE! It retains the memory of results. There's another without the OBDI cables and it has the same tester. It comes in a black pouch. It has a cigarette lighter adaptor. Out-of-the- box it tests from 1984-2013. It is updatable with a USB cable from EBAY. It comes with OBDI cables for Ford, G.M, Chrysler, and Toyota, and a OBDII adaptor. There are penlight batteries under the cover at the small screw. It is well- lit! EBAY has it.

[@enlightenedwarrior7119]

your a good man to help people God bless u sir

[@farmboy30117]

Thanks Luke!

[@dandeertz2544]

Thanks I needed to know that as I'm working on a 90 Silverado with a no spark issue😮

[@badassbees3680]

Thanks Brother best one on KZbin!!

[@farmboy30117]

You're welcome!

[@badassbees3680]

@@farmboy30117 you got me back on the road ! Thanks again!

[@coreybarber3779]

Thanks for info, trouble with my 89 tbi also.

[@cccalhoun]

If you fellas cannot find the brown wire, look under the passenger side dash inside the cab. Brown wire with black stripe. I have a 1994 k1500 5.7L that I am restoring and mine was behind the glove compartment next to the computer. It can also be closer to the floor behind the foot-well light, by the carpet and blower motor. To set the timing: Unplug the wire turn on the truck and wait for the engine to warm up find Top Dead Center (0 degrees) on #1 sparkplug turn off the truck reconnect the wire turn truck back on, and the computer will set the advance (usually 20 degrees) Drive around a little bit afterward, because the computer will learn as you accelerate and slow down and further fine tune the timing

[@farmboy30117]

Thanks for the info!

[@loymoon6015]

cccalhoun

[@DeMacChannel]

cccalhoun I have a 1994 GMC pickup two seater I think it's a Stepside and I have the same exact problem and I got everything and nothing is doing the trick. It'll drive for a few days as soon as I buy a new battery and then it just dies and I think that's the problem is the brown wire. But I don't understand what do you mean turn or go to the number one spark plug and 0 degrees? And also so you're saying I can go behind my glove compartment which I already found all those other relays and change them so I can find the brown wire there undo it then I could turn my car on and then turn it off find the one spark plug and do what how do you turn it through degrees what do you mean by 0 degrees I don't get it I really appreciate all this information I've been looking on KZbin for 2 weeks and on the schematics and everything you can think of especially being broke

[@DeMacChannel]

cccalhoun or is that too just set timing I still don't get it do I do all that first the bypass does starting point because my truck won't turn over are you saying unplug the brown one and my truck will start and then do it all over again for the timing can you give me a detail I know you don't know me I would appreciate it

[@ericmesi1764]

I have a 92 gmc k1500 350. Only thing I have not replaced was the Ignition Control Module Relay. I ordered it see what that does. Currently it acts like no vacuum advance. It cuts out won’t pull. I had a pulsing idle replaced the knocks sensor that solved that I’m almost at 100 percent now. I’ll put that Ignition Control Module Relay in see if that’s it. I changed the cap and rotor wires and plugs. New coil as well. New ecm new computer. I bought this truck brand new so only the Ignition Control Module Relay hasn’t been replaced. Can anyone give me suggestions please?

[@kaduisaui8016]

Can the ignition module be placed away from the distributor? Can I mount it against the firewall with a heat-sink?

[@michaelhughes5453]

Thank you, Sir, for the heads-up...

[@Milo30066]

Thanks for sharing the details.

[@stevedeleon2829]

You guys kick ass thanks for the info

[@iblackbeard]

Replaced the ICM, cranked right up!! Thanks Man!

[@farmboy30117]

Glad it helped!

[@gashan72]

No spark then u replaced icm?

[@gashan72]

I had code 42 n 43 if that mean anything

[@patrickoneill9650]

gr8 video very helpful with key information TY

[@khailerreed4188]

I'm collecting 88-95 Chev. GMC picked-up 2 today 4×4

[@farmboy30117]

Good deal! I think those models will be very valuable in the coming years!

[@robertshafer6168]

You want another one

[@joshuacollins5222]

I've got a 89 k1500 with no spark. I've put an inline tester on 2 different plugs and it flashes once when I turn the key on and nothing while cranking. I tried the bypass you showed and still no spark.

[@jonathanwise4252]

Hey farm boy I've been watching your videos for awhile I have a 94 C 1500 4.3 on the passenger side just laying on the intake there's a female plug with solid purple and solid blue wire going to it from the harness but it's not used someone told me it was for the service techs to check RPMs at factory if so I should be able to get another pigtail and wire a tach into that plug correct

[@farmboy30117]

I have no idea. It's easy enough to hood to the white wire coming from the distributor on these trucks.

[@bonscotty67]

I have the same thing laying on my intake Jonathan... Did you ever find out what it was for? I suppose Google search for a wiring diagram could tell me but curious if you found your answer

[@angeliamattingly]

Where is the Electronic Spark control module located on 1993 Gmc Sierra 4.3 6 cylinder? The book we bought says near the throttle body or behind the distributor mounted to the fire wall. We can't seem to find it

[@TheRealAce]

It's inside the area the distributor cap covers... It has two screws holding it in and it has two connectors with wires hooked up to it...

[@frankyeager2298]

Clean and dry under the hood👌

[@prestonwhitaker9669]

I'm having a starting issue, I have a 94 1500, I replaced the motor with 1 out of a 89 model, new plugs and wires are on it!! If I were to do this would this be the culprit?! I did not replace the computer or anything! Its spinning over but wont turn over for me. Any ideas would be appreciated!!

[@farmboy30117]

Will it fire on starting fluid?

[@calambres6614]

Hell yeah thanks for the information

[@farmboy30117]

Glad it helped!

[@brandenshay7375]

Buddies truck has an issue and we don't know where else to look! New cap rotor coil ... Cranks gets fuel does not fire but will fire with a small shot of starting fluid.

[@less2worryabout]

thanks this is helpful i still aint got no spark after doing all the same mess its a 1996 454 in a Winnebago i wonder how to set the timing or if i need to also can i set it without running by just cranking?

[@AK2HI]

i have a 92 s10 pick up and this may be my problem, i changed the coil and cleaned up distributor but still randomly starts, I'll try ti unplug the brown wire you pointed out and see if it helps, thanks

[@farmboy30117]

It should still crank with the ICM before swapping to the ECM. The brown wire connects the ECM to the distributor. The only time you should have to disconnect the brown wire is to do the initial timing.

[@AK2HI]

@@farmboy30117 ok, well i think its my distributor and rotor, what a ding dong i didn't check for spark first and just did and there's nothing. thanks

[@paulhyde4899]

thank you this is very helpful I will try tomorrow and update you

[@IntenseKustoms]

I'm hoping you can answer this. My truck has a rough idle like it's not advancing the timing. I have done cap, rotor, coil, ignition control module and even the distributor at this point. When we unhooked the wire to set the base timing the truck dies. It show's a code 42 which comes up as ignition bypass circuit error.

[@stevemuro3365]

What was setting the code 42?

[@stevemuro3365]

Did you ever figure it out

[@joeycarballosa8295]

I'm getting fuel but no spark what do you think is?? Truck was running great than it wouldn't start out of no where

[@farmboy30117]

I had the same issue several years ago. It was the pickup coil but I just replaced the entire distributor. It was easier and cheaper than just the coil.

[@solidangel5298]

Yea I change fuel pump ,injecters,ignition module , thinking it was that . nothing so then we went and check the grond on the injecters and no spry so that's the issue . I tested it by touching on any ground and spayed.. but how can I fix this problem... i really appreciated your help ...

[@farmboy30117]

Sounds like it isn't getting a ground signal from the computer. Might be a bad connection, wire, or PCM.

[@MrCoffeekelly]

solid angel the ignition module can go bad to where it still has spark but doesn't send a signal to the ecm telling it to power the injectors.

[@JorgeLopez-um6pn]

solid angel did u find out whats wrong ? i have same issue. lots of new parts pump. injectors. distr. n ign. all of a sudden i crank and no spray whats going on?

[@davidmiles4394]

Your problem is the computer

[@davechambers5387]

you should remove the 2 ECM fuses for 5 minutes , as well .

[@keyonivory3724]

are you talking about the proms in ECM

[@artiepilot8023]

Just looked at your video I got a 1994 chev 1500 Cheyenne I haveing trouble some times it will start and run when not in gear then I put it reverse and it will cut off and don't want to start no more I would have to put gas in the carberrader to start .. can you help me with this problem..

[@DroppinShellzz]

So i have replaced the ignition control module, ignition coil, distributor cap, rotor and wires, and plugs. I am getting fuel, but still having trouble with it not turning over. When i get it to turn over, it idles but then I turn it off and try to start it again and it won't start. Should I try removing that connector still? What is weird is whenever it does turn over it the radiator fan kicks on right away, but I think that is just a stuck thermostat so going to replace that as well

[@jacobrothney8269]

I have a 1991 chevrolet k1500. I changed my throttle body gasket and started the truck up and noticed a minor leak so I shut the truck off. After I tightened the hose I went to go start the truck again and had no fire. I changed the cap and rotor and cleaned the module but still have no fire. Having trouble find the brown wire but I was wondering if you may have an other idea to why I would not be getting fire?

[@ufochannel01]

hey great video you explain things very well that help so much! so my truck 89 chevy 250 it seems to run well but limps around 55 mph and doesn't want to go faster pulling a light boat. so i checked codes since the light came on and they read 32 and 43. the 32 says map sensor and 43 is bypass ignition signal failed. what's your opinion here. i was going to get the map sensor but what do i replace for 43? thanks again for the help you give.

[@jonathancollins2535]

Correction I don't have that clip ur talking about. I ha e the bigger squar one that holds a fuss

[@gelatinskeleton8745]

This could be my issue... mine is a 90 Chevy 350. Replaced three coil module 3 times, last one with ACDELCO. Still isn’t starting. I’m gonna look for this computer wire tomorrow. Pull it... crank it... and see what happens.

[@farmboy30117]

Good luck!

[@chrishampton5915]

Great video, but I can't figure out why my 95 GMC Sierra sometimes runs great but when you kill it it's lible to not crank again for a week, sometimes I can pull it off but it's got me puzzled any answers?

[@farmboy30117]

Impossible to diagnose over the internet. When it won't crank, check fuel and spark to see which one you don't have. That'll help narrow it down.

[@AxSxKxONE]

Please help -Ok I have a 88 with the same coil - on the side with the thicker wire -the wire wire comes out of the plug that goes to the cap that plugs into the coil comes out and is cut - it’s Allways been like that - where is it supposed to go 🤷🏾‍♂️

[@farmboy30117]

I believe the white wire would go to a tachometer

[@torquewrenchdaddy8032]

Good info. Thank you. I replaced the complete distributor,coil,cap,rotor,plug,and plug wires. Set timing and started up. Set base timing. Shut off truck and will not start back. Any ideas ?

[@davidcollis4758]

This also applies to '87 Chevy P/U trucks.

[@user-uj3zk2cx8t]

87-95

[@williambarreto4967]

Ok thank you very much for your kind answer, the dealer has the new pickup coil and also the distributor cap and rotor, will hey have to change the distributor shaft?

[@farmboy30117]

It's possible that something is bad on the shaft, but not too common.

[@degenerategrappling6503]

Not sure if anyone is checking this still. Got an 87 gmc sierra 1500 with dual tanks. Stopped while driving. Fuel pump would intermittently turn on. Replaced with a new one and new filter. Turned on once and now does not. We tested by hooking up to a power source and it works. Checked all connections with test light. Engine has spark but no fuel will produce through the TBI due to the fuel pump not kicking on. This is the driver side tank. Passenger side did not work when I bought the truck. Suggestions??

[@farmboy30117]

Check the fuel pump relay. If that's ok, then check the oil pressure sending unit. Power to the pump is initially through the relay via the PCM then once oil pressure builds it is powered through the oil pressure relay.

[@degenerategrappling6503]

@@farmboy30117 thank you very much I will try that

[@josephpuchel6497]

Hey Farmboy what up nice tutorial Joe from Jersey

[@farmboy30117]

Thanks Joe!

[@calebcrumley9307]

I have a 94 Chevy suburban k1500 350tbi and the ecm fuse keeps blowing randomly and can’t figure out why it only does it randomly wondering if you have any insight on how to trouble shoot it

[@farmboy30117]

Sounds like a wire with a bad spot that grounds out every now and then. Have to trace the power wires out and see if any are chaffed.

[@kyliancameron2364]

Hey I'm having the same problem as a couple of the guys on here mines a code 42 tho and it says it's the est how do I go about fixing this problem

[@thesetruths1404]

Hey regarding that wire that isolates ignition from ECM...I have a 1991 Chevy 1500 and there's a plug there but it's white with black stripe. I unplugged it and tried to start but still no start. My issue is either ECM, ignition module, or pickup coil. I wish I could post a pic of mine. It's in the same area you pointed to but is a different color.

[@farmboy30117]

I've heard they are in different areas depending on the year.

[@ambergormley6325]

I have a 92 GMC Sierra V6 5spd.. I'm having issues with starting the engine.. it'll turn over but won't start.. May have a compression issue.. at first my fiance and I could spray some starter fluid into the intake and it would fire up.. what are some tips or thoughts on the issue?

[@farmboy30117]

Sounds like it's fuel related. When it fired up on starter fluid, did it run ok? Try cycling the key 3-4 times to prime up the system. Make sure the oil pressure gauge is showing pressure when cranking, a bad oil pressure sending unit could possibly quit sending power to the pump. I'd rule out the pump/wiring/relay before looking at the injectors.

[@randallspreadborough1206]

Nice video I’ve been looking for advice on upgrading the engine that I am running. I just purchased a 1990 454 cubic inch engine installed in a motor home. 55000 original miles means it was parked most of the time. My other car is a 2003 Express 3500 with a 6.0 liter engine. It has coil on plug ignition which I fell in love with. Trouble free for 330000 miles so far. Is there any way to modernize the 454? Right now I’m just replacing the plugs and wires and haven’t looked at the distributor yet. Thanks for your input.

[@huntercox1859]

You you can do what ever you want to it. You can run coil on plugs all the way to a stand alone ecm. Just takes a lot of money

[@matron81]

I have a 1991 K1500 350. I was driving down the highway last night and it started sputtering then died. It has been stalling out the past few days sometimes when I am in gear and stopped at a light or if I drive at very low speeds. I smell fuel when trying to crank and we sprayed some brake cleaner in the top. Changed the control module in the distributor out with a known good module still the same. We noticed that the spark in our tester was very orange and dim, it usually is bright blue. There was some dirt on the contacts inside the distributor but we cleaned them off and the spark plugs looked OK but probably need changed soon.. but still should be operable. Any suggestions? The motor, distributor cap and entire distributor motor is less than a year old.

[@farmboy30117]

Well it's either going to be fuel or ignition related it sounds like. I assume it cranks right back up? Have you changed the fuel filter recently? No codes?

[@matron81]

No, it will not crank.. Turns over and we smell fuel. Spark seems very weak.

[@matron81]

When we use our spark tester (small tube put inline with the spark plugs), the spark is very dim. It is normally a bright blue color. We have replaced the entire distributor module and I swapped out the starter with a new one just for good measure because I have a lifetime warranty on all of the parts. It still will not start.. the only thing I think I can check for is to see if it has an ignition relay thats gone bad or the ignition switch itself is bad. Why would it have a weak spark?

[@chronosun13]

matron81 did you find out what it was?

[@randrrcscorbin-tyler3998]

I need help 92 Chevrolet c1500 with 4.3 tbi ive got fire at the coil but no spark at the plug wires

[@melindaortiz9741]

Bad rotor dirty distributor cap

[@harmonpatch6858]

Very helpful, thank you

[@danl878]

Mines a 1990 suburban 2500 and i think its the same thing mine just dosnt crank at all

[@jonhsmith2706]

Did you figure it out?

[@danl878]

@@jonhsmith2706 yea i did

[@jonhsmith2706]

@@danl878What was it if you dont mind me asking I have the same issue on my tbi caprice

[@dennisryeater9047]

Sir can you tell me if there is a difference in a 94 and a 95 engine tbi 4.3 foe a s10 chevy pick up

[@farmboy30117]

I know they went to a vortec 4.3L which had a balancing shaft in it. Not sure if it was '94 or '95 though, but I'm thinking it was '94.

[@brycepeters964]

Could that why effect it on start up? I had to change my oil pressure sending unit and when I put my distributer back in timing was right but on start up it wants to die right away but if you give it alil gas and let it idle at about 2000rpm for about 30seconds then it's okay.

[@farmboy30117]

When you timed the distributor, did you unplug the wire so that the computer wouldn't effect the timing? Not sure, but it sounds more like a problem with the Idle Air controller.

[@brycepeters964]

No I didn't not unplug that thing. I had no idea about that plug until I watched this

[@poppagrouch4781]

Looking at a 93 Chevrolet, decent looking truck. Guy says it had some wires cuts so he bought a wiring harness... Question is, how difficult is it with replacing the harness ? And or maybe just the ignition part of the wiring harness...

[@farmboy30117]

I wouldn't think the engine harness would be too bad. There's not a lot of sensors compared to later models.

[@marksturgill6363]

Can you tell if a 95 to 93 4.3 will go in a 81 4.1 without any problems

[@smiley454jmw]

Sometimes that plug is behind the glove box

[@gtuttle4]

Great video! I was hoping you could help me with a problem I am having on my 89 Chevy 5.7 K1500 truck. My initial problem was it would not start, because it's 33 years old with 150k mile I thought I would replace the fuel pump. This was not the issue, still would not start so I check for spark, no spark, so I replaced the primary coil, pick-up coil, ignition modular, distributor shaft, cap and rotor button. It started right up and ran. I unplug the EST plug (advance timing) to set base timing on TDC. But with the EST unplugged it will not start. Any idea?

[@farmboy30117]

If it will not start with the wire unplugged, more than likely the ignition module is bad. I've seen it where the ignition module is bad when they're new. I think Autozone can test it, or they used to be able to test it. Don't buy one from Autozone or Advance Auto. NAPA is your best bet if it's bad.

[@gtuttle4]

@@farmboy30117 Thanks for you quick response. Since I wrote you, I set timing on TDC with EST plugged in and it ran smooth, I took it around the block and it even had a little more pep. How can the ignition modular be bad yet start and run so well? I put an AC Delco ignition modular from Rock Auto hoping it would be a good one to buy. Do you think it will hurt anything to run it like this?

[@farmboy30117]

@@gtuttle4 I probably misspoke about the ICM. I'm no expert on this. Here's a good video that explains how a GM bypass system works: kzbin.info/www/bejne/lXrNmZxtls5kfrs I'm not sure why it won't crank with the reference wire unplugged unless that's not the reference wire you're unplugging.

[@gtuttle4]

@@farmboy30117 Yeah, I just now found his video, I'm sure it's the EST plug, it has the tan and black wire plug, although the location of the EST was not where it was suppose to be for a '89. It's located on the firewall on the driver's side like a '87 model. Thanks for your help!

[@mritron7649]

Always get the AC Delco ignition control module D1984A or D1943A I believe they are the same. And always use actual thermal heat sink paste and not that clear di electric grease. The aftermarket china made ignition control module are junk.

[@michaelsalas9280]

where is the negative wire on the elect ignition

[@nathannemeth6750]

1990 Silverado, 5.7 all lights on dash work when turning key to on, try to start and nothing, starter wont rotate but still powers everything. tried two brand new starters, same problem. one day it starts, sometimes it doesnt at all. Any suggestions?

[@dianesills8060]

i have a 82 gmc and i get lights on dash when i turn the key on but i get nothing at all ytrying to start it

[@barbaraqueen8822]

NCS on transmission or look under mate on driver's side you will see black tar tap under it is a fuse

[@less2worryabout]

not sure how to test this type of coile either boss

[@hangoversamuiadmin3163]

Quick question. I have a 94 Silverado c2500 with a 5.7L. If I use starting fluid it starts and runs fine. No starting fluid it just cranks till the cows come home. This started after using engine degreaser and power washing it off. It started fine after the spray and I let it run for a bit to dry everything up. Was looking fir an oil leak. Any help would be greatly appreciated.

[@farmboy30117]

Sounds like a fuel issue but very weird for a gas engine to act like this. No idea on this one.

[@hangoversamuiadmin3163]

@@farmboy30117 I noticed off or the key on no fuel comes out of the injectors. So guess I can start tracing and testing there

[@farmboy30117]

@@hangoversamuiadmin3163 Maybe start with the fuel pump relay

[@hangoversamuiadmin3163]

@@farmboy30117 Will do, thanks for the help

[@hangoversamuiadmin3163]

@@farmboy30117 Ok, so replaced the fuel pump relay, same issue, reset the computer and it was flashing code 21, read about it... cut a hole in the bed and replaced the fuel pump... not the problem... Its a long bed so was not able to lift it myself and I filled the tank like a day before this started... Today went and got a fuel filter and a new TPS... Replaced both of them and now it works fine, my code 21 is no longer there so guessing it was the TPS that caused the issue. I can honestly say after reseting the computer the idle is perfect now and it even seems to run better! Thanks for your help man very very much appreciated!

[@kyliancameron2364]

it's a 91 chevy c1500 with a 5.7 350

[@ShadowOppsRC]

Yep. Thats is no big block but the small block and big block both have a similar ignition setup.

[@jeanjackson7001]

I gotta question I have 92 chevy k1500 after tightening thepower wire to the ALTERNATOR my fuel pump wires burnt I replace the wires where the burned a little that issue resolved but while doin so I hooked them straight to the battery to test the pump it still work UT after wiri g it back correctly I have no cli king no spark absolutely nothing when I turn to the key to try and crank the the truck

[@Jay-zx8fj]

the module is to the left of distributer? with one electrical plug?

[@farmboy30117]

The ICM (Ignition Control Module) is under the distributor cap inside the distributor.

[@Jay-zx8fj]

@@farmboy30117 thank you sir. what is that thing called that is to the left in your video it has a green plug on it and a vacuum line

[@Jay-zx8fj]

MAP sensor?

[@charlesstone1440]

Great video! I have a 1992 GMC Sierra never had a problem until today. Let the batter die and gave myself a jump truck started up fine but shut off! Now will not start. It cranks but won’t turn over!! Any advice would be appreciated. Thanks

[@jamestapia7431]

Did u find out the problem same exact problem same truck

[@jamestapia7431]

Replaced a lot of parts

[@xrjockey86]

Is there supposed to be battery voltage from the coil to the icm? My 1991 chevy 5.7 decided to not start last night. No spark. Replaced the icm hoping that would solve it. Now I'm stuck.

[@Michael-wk4yo]

Me too bro did you figure it out

[@xrjockey86]

@@Michael-wk4yo Pickup coil in distributor.

[@xrjockey86]

@@Michael-wk4yo Kind of funny this came up. Last few week, my pickup was running like crap. Getting crappy fuel mileage. Apparently I didn't put loctite on the distributor bolt when replaced the distributor. It backed out and slowly spun my distributor. If your pickup coil is bad and you replace your distributor, make sure you use loctite on that bolt! Good luck!

[@richardjhonson6272]

I have a cap on my distributor. The screw keeps sinning and wont come loose any suggestions

[@bradleyrobbins285]

I have 94 GMC tbi 4.3 v6 vortec, was driving it, shut down like u turn key off no back fire, pop, no noise, I've checked it no spark, will crank but want start, what's my troubles, also have just replaced cap button an wires (+spark plugs) took ingintion modugel off had it checked an was good

[@tedthomas2753]

Have a 1994 chevy 1500 the timming is ok put a new coil on heard at arcing noise it's arcing where the two plug wires plug into the coil only arcs every so many seconds. At the top of the wires

[@davidburks775]

Whats the red inline fuse thats has an orange wire on other end on the distribution fuse block

[@bomurray5551]

Farm boy I need some help I just bought a 89 Chevy Silverado 350 four-wheel drive and I have no idea what to do I'm having the same issue to start no crank no spark and my battery terminals getting hot when I try to turn it over help please..

[@farmboy30117]

What does it sound like when it's turning over? Hot wires means high resistance, so either bad terminals, grounds, etc. You live in salt belt?

[@bomurray5551]

@@farmboy30117 it sounds like it wants to turn over..but it wont..

[@meggavigan2021]

How do you replace a 93 Chevy 3500 with a 5.7 v8 manual control box wiring hardness

[@andylaronde]

what about only one injector working (left) and no spray from other so running on half carb and i dont have a tbi tester

[@farmboy30117]

Can you swap the connector from the good injector to the bad one and see if the injector works?

[@rickywalker-fi7ds]

i have an unrelated question. i have same setup, recently had to replace ignition module under distributor cap. its run fine for a while, until starting up a hill the other day and all of a sudden got a loud rattling clanking noise from engine, and loss of oil pressure down to half (20) instead of 40. any ideas? the top side looks good all rockers move good, bottom side looks okay as far as i can tell, didnt get anything out of oil pan. whats your suggestion

[@farmboy30117]

Doesn't sound good. Loss of oil pressure sounds like a clearance issue. Maybe spun bearing? I'd definitely want to pull a couple of bearing caps off and look. Good luck.

[@davesmith4032]

4.3 the same way ? Thankyou for any information you can give me on this God bless

[@farmboy30117]

Should be pretty similar.

[@chooch352]

OK i WOULD apericate YOUR HELP GOT A 1988 CHEVY SILVERODO will run good for about 30 minutes then shuts down for 24 hours changed plugs and wires and rotor cap and coil too.

[@prestondonohoe1016]

my 92 5.0 had been falling on its nose at half throttle for 2 years but ran great just didn't have full power plenty to go 85 down the highway then from nowhere it's chugging and missing any ideas fuel pump is good

[@farmboy30117]

Preston, there is so much that could be wrong. Did it set any codes? Since fuel is good, I'd look for vacuum leaks, distributor problems (ignition modules are notorious for giving issues), or clogged injectors. I assume you changed the fuel filter too.

[@jeffnorbert1871]

@@farmboy30117 EGR malfunction or clogged cat/restricted exhaust are likely if fuel pressure is good at throttle body and injector spray pattern is ok and ignition timing is reasonably close.

[@jeffnorbert1871]

By the way, faulty distributor cap is possible too. Spring under the button breaks sometimes and you can't see it.

[@carljackson4028]

He forgot to mention the ign. control module under the distributors cap it usually goes bad

[@farmboy30117]

That and the pickup coil. Heat kills those ICMs and most aftermarket ones are junk.