Chevy Trailblazer: Will Not Run A Drive Cycle

In this video I have a look at a customers Chevy Trailblazer EXT with the big 5.3 that has a customer complaint that the vehicle will not run a drive cycle. I give you a small list of items that will inhibit the drive cycle and we find the issue right off the get go. However a Napa part throws us a red herring.
-Enjoy!
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Due to factors beyond the control of South Main Auto Repair, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. South Main Auto Repair assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. South Main Auto Repair recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of South Main Auto Repair, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained.

[@frankvucolo6249]

When you put that calibrated resistance tool on the circuit and got the proper expected feedback from the pcm, I said “dang, that’s cooler than the other side of the pillow!” You never stop learning me stuff, Mr O!

[@COBRO98]

A potentiometer! Very useful in automotive work. He used that to rule out a fault on the PCM side

[@steveb6103]

You've said it so many times. " Just because it's new doesn't mean it's good"

[@rationalguy2744]

I prefer used parts because they have been tested.

[@onemechca]

Brilliant diagnosis Eric....aren't you tired of aftermarket companies producing junk that can cause you to go down rabbit holes like in this case?? Thank goodness you have the experience , service info and gut instinct to know what is right...keep up the video's bud.

[@pootthatbak2578]

Dont think of it as junk, but inexpensive stuff that couldnt pass a strict quality control test

[@jblyon2]

@@pootthatbak2578 That's business 101. If too many of your products can't pass quality control, just get rid of quality control. Problem fixed!

[@stevewesley8187]

@@pootthatbak2578 not always so inexpensive........

[@michaelgiannone2192]

I’ve learned. Anything electronic buy OEM

[@pootthatbak2578]

@@jblyon2 no..the problem is, before chevy or toyota or whatever oem seller buys the same parts from a manufacturer..could be the same part NAPA or standard sells, the part will get QC tested. The testor passes the parts that are closest to oem spec. Then the rest go to the " undersellers, or acme cheap discount auto parts inc

[@wyattoneable]

I enjoy hearing you think out loud to your approach to these challenges.

[@Dee12327]

Eric is a very humble person, he always says he’s not very good at the software side of things, yet he shows very detailed videos like this one that goes in to depth on how he came up with his findings. Ive learned a lot from this channel, and always look forward to new videos!

[@clintprice2123]

What a great way to start the day, a new South Main Auto video!

[@Robalo-2660]

Eric, you have taught me so much over the years. I would replace a part and call it good. You have shown me the way of a true master. Trust but verify. I am so grateful for the time and effort that it takes you to produce a video and share your knowledge. Much love my brother, you inspire!

[@mrkttrdr2919]

one of the best vids u have done, because it goes to the heart of not overlooking a simple sensor that could be junk even if its new, great work as always, thanks for posting

[@SouthMainAuto]

Thanks 👍

[@typingnow1742]

I just had to post that I think this guy is the most brilliant car mechanic on KZbin. I’m not joking, I’m in awe every time I watch one of his videos. Guys like him are rare, it’s like a natural intelligence. An unusual ability to understand and manage complex problems. I feel like such a mental midget watching this guy. He ends with “If I can do it, you can do it” but that’s simply not true. The only time he ever lies in his videos.

[@warbirdwf]

I just wanted to say two things. 1) I'm sure I speak for others in saying thanks for all the hard work you do in making these excellent videos. 2) I hope you're making a very nice income from KZbin for all this hard work!

[@vanceblosser2155]

I always learn something watching your videos. I was in IT for over 30 years, jack of all trades doing Cobol programming, newer languages, interfacing PCs and Mainframes, and PC repair. Your logical approach is the same as is used in repairing PCs OR in finding a bug in a program and I'm always impressed with your clarity of thought. Keep up the good work and I wish you continuing success!

[@airborne63]

One more reason to use OEM parts......less expensive in the 'long-run'. Delphi used to be owned by GM, so the Delphi parts should be 'compatible'. Another great diagnosis!

[@JackdeDuCoeur]

I like the way you incorporate lunch into diagnostics. Nice work

[@DIYDaveOK]

Fantastic diagnostic approach to use the varistor meter. You'd have made a fantastic software developer! Thanks as always, Eric!!

[@mrsargemeister]

I'm convinced Eric could have been a world class doctor or surgeon with his skillset.

[@richb.4374]

Eric claims he is not an electronics guy...yet he has a brilliant understanding of how automotive circuits work.

[@SouthMainAuto]

I just get lucky once in a while Rich. I'm not an electronics guy, trust me.

[@Yoyo81828]

As an engineer, Eric could definitely kill it in STEM if he wanted to. Critical thinking skills for days

[@kenj.8897]

​@@SouthMainAutojust damn good 👍

[@Todd_S]

I love watching all of the Silverado visits. I have a 2012 Chevrolet Silverado 1500.

[@MrSahdaddy]

Another fine example of just because the parts is new, doesn't mean it's good!

[@joehomanick]

In Philly 2000 an up can have 1 incomplete. You just have to get the evap to go befor the cat . Once the evap is ready it can have codes for the cat but the light can not be on . So a key cycle would turn off the light and try the cat test again . Just have to slip it through then .

[@arniebriscoe2978]

Eric, we'll say 40 years ago, I built a very strong 454 for a hot shot driver in his 78 one ton Chevrolet. Put a new standard temp sensor on and anytime he got over 60 mph and turned the a/c on the temp would climb to 230 degrees. It was using a quart of oil every 500 miles Pulled it apart, took l out the chrome molly ring and went back with steel rings trying to dry up the oil usage. Still overheated. Finally put a thermometer in the radiator, showing @ 160 and the gauge at 210. It would not get hot enough to seat the rings. Put the old senor back on, temp got right and got the engine hot enough to seat the rings. no telling how many hours and money lost trying to figure out it was just a new bad sensor. I feel your pain.

[@anthonyshriner4362]

If I didn't live in Alaska, and lived in New York. This guy would be my mechanic for sure

[@CC-kr2fs]

NAPA=not all parts active. It'll get ya everytime. wel done Mr O

[@terminallygray]

Hello Eric, possessor of Associates Degree in Electronics here to put in my 2¢. You had mentioned that you don't know how a PCM handels input data to calculate stuff and produce output to whatever it's sending the signal to.... BUT you wish you did. Experience tells me that the only people that know that stuff are the clowns that engineer it because it's proprierity information for a peoprierity system. Sure, there are techs and repair people that are curious enough to study it and find out what works, but It's not like you can take a class or something to find out. That's a really good plan used to determine that BOTH temp sensors were bad parts. Unusual circumstance calls for a solid plan and you had it. You are a really good repair type person/ auto tech. I don't know what you charge your customers but they do get their moneys worth on these type of repairs. A combination of knowledge, skill and experience.... it's too bad that there aren't more guys like you in the repair business. THEN we would feel like we are spending money wisely.

[@tinyavenger20playsgames28]

Seems about right. Cheap chinesium sucks and costs the customer more. Wish i had a mechanic like you here, woulda saved me tons of money. Thank you Mr. O!

[@haywardsautomotive6156]

Nice diagnosis. Most shops would have seen a new CTS & looked elsewhere. I'm retired now but it is so enjoyable watching you diagnose & work on cars. Just had hip replacement surgery & I'll get back at it but on a limited basis for some of my older customers but now the priority is bass fishing & tournaments. Thanks again for enjoyable videos!

[@springfield4522]

Really like how you take us along on the diagnosis trail. Thanks Eric!

[@gregbellinger5765]

The most successful advertising is providing knowledge, skills, and attributes when solving problems. Eric nails it without embarrassing people too much. He does make people wonder why dealerships don't do deep problem solving. I guess the answer is not enough ethical standards. It's one thing to throw parts at a problem to solve the problem, but throwing parts at a problem and still not solving the problem is criminal. Mistakes are normal but trust is the most important result.

[@seastacker8582]

Great diagnosis, but the biggest thing I learned is how thankful I am to live in a state that doesn’t do vehicle inspections.

[@budc2578]

Just moved to a state that eliminated vehicle safety inspections. At night it’s not uncommon to see 3 or 4 vehicles with faulty headlights or tail lights. Taking a walk thru a parking lot reveals numerous worn tires.

[@takeahikeforlife]

I read through most of the comments and didn't see anyone suggest this, but being a heating/a/c guy, I would suggest that to be absolutely sure of the internal temp of the sensor, soak it in an insulated cup of crushed ice/water. This would put it at exactly 32 degrees and remove all doubt as to the actual temperature of the sensor.

[@billy-sx8wx]

Yes but he was trying to confirm it isn’t a wiring or pcm issue.

[@CalebTG]

Thanks again Eric for a solid and honest repair!

[@mark95b77]

Eric, Outstanding video presentation. Really appreciate how you break things down and insert the small bits of information that give the viewer a extremely clear understanding of the subject matter. Thanks again,

[@jasonbailey6797]

Great video. Great explanation on the coolant temp sensor and the way it works with the drive cycle.

[@stationaryenginesworldwide]

Awesome video Eric .I always look forward to your approach on the videos you make .and how you do your investigation.. Truly a master in your field.... Thank you

[@djmartin4776]

Glad you were able to take us along for that one. You are legendary my guy

[@280813jb]

Great diagnosis Eric.

[@lgh081960]

What we have here is a qualified experienced automotive mechanic dealing with the intrusive electronic components that want to monitor/dictate everything related to a poorly designed system. Automotive engineers 👎 Parts designers👎 Old school mechanics 👍 And if you happen to get in to a collision, your car will rat on you big time. Thanks Eric, you are helping me go through another crappy Canadian winter.

[@rationalguy2744]

Lots of good stuff here. My Subaru ej25 was running rich enough to wreck the cat. The coolant temp sensor was bad. The replacement stanpart was not calibrated ideally. Oem from a dealer solved it. Reducing part numbers by "retionalizing" their inventory could lead to unfortunate compromise being made by hasty penny counters. Their gain was my loss.

[@ronaldbrosius7488]

Excellent video!! These are the best types of videos. Your very intelligent, and a Excellent mechanic/tech. Your costumers don't know how great they it,having you as their mechanic!!!

[@richardr2238]

Love these longer videos. Thanks Eric you made my day !😄 One more thing, so nice not to hear air tools and jack hammers in the backround !

[@kenchilton]

Knowing that the coolant temp is a common issue is why you make the big bucks. Thanks for the video!

[@andrewg6238]

Wow! You're thought process is so impressive! I love that you share that as well. It is sad that the places that manufacture items that are supposed to fix things make them unreliable, that dang BOB guy! Thanks again for what you are doing and tell Mrs. O. to keep you in line!

[@rik999]

The change in resistance vs temperature is logarithmic for those thermistors. That chart you showed has enough data points to plot a log curve so you pick off interpolated values of resistance for any temperature. Also you could make a more versatile dummy thermistor test tool by putting a 100 ohm 10 turn pot in series with the one you already use. Allows for finer adjustment of resistance values. Might be useful for those picky GM drive cycles. By the way, the multi-turn pot I saw you using should be accurate enough so you don't have to confirm all the time with an ohmmeter (saves time).

[@stephenbell9257]

You still need to check the resistance with a meter to get accurate results. With a multi-turn pot you can set the potentiometric resistance ratio very accurately, typically 0.1% error, but when used in rheostat (variable resistance) mode the errors are greater due to the tolerance of the end-to-end resistance, typically 5%. Directly dialling the resistance value could have resulted in an error of up to 5.1%, which wouldn't have been sufficiently accurate for the testing that Eric O was doing.

[@markchidester6239]

I was yelling at Eric to dial in a temp on the chart then test the variable resistor.

[@KC-vp7wn]

I ran into a similar issue with my Holly sniper. The temperature reading was off with the sensor that came with the unit. I ended up purchasing a Delphi temperature sensor and that cured my problems. Just to let you know, there are calculators on the web that will give you the exact ohms reading to temperature. Great job and always great videos!

[@JOHNSUE28]

KC. How about a Link?

[@edwardmyers1746]

I love when both you and Wes post videos at the same time essentially

[@demetriusbarrett2152]

I like your videos it shows once again you are the man

[@geordiegixxer]

Excellent diagnosis again. Wished you were over this side of the pond

[@edwardsmith9049]

Mr Eric o these is a great video. This content was so difficult that I was confused trying to figure what was going own. Until you explained the whole process. Thank you for teaching us. Again great content keep up the great work.

[@joecnc3341]

I love to watch your detective approach to solving these types of problems. You do a great job of diagnostics and sleuthing out the problem.

[@jorgefernandez-mv8hu]

Very Nice and detailed diag. It is so frustrating when you are headed down the right path, but a bad new part throws you for a loop. Thanks again.

[@fixingitrightish]

That clicking is a blend door actuator. The ones in my Impala make the same sound when going bad. It's turning all the way in one direction and trying to keep turning, jumping teeth on the gears inside the actuator

[@wk7060]

We get value from all of your videos! Thanks.

[@GTCGreg]

No substitute for proper service data and the experience on how to use that data. Great job, Eric.

[@DanMestayer]

Thanks for the operational principals explained. This troubleshooting the drive cycle will help us home mechanics.

[@russellbomgardner3817]

big help for me Thanks Eric . my 06 chevy express 3500 has been giving wacky engine temps for a couple years. I replaced the sensor and still the same. You gave me a lot of great insight and info. I really like watching great diagnostics at work. You da man😉

[@JHart-rd3nx]

I love watching you and your testing equipment go to work. Reminds me when dealer could not tell me why car would shut down after 10 minutes of running. Always happened to the wife never me until 1 Sunday morning. Waited 15 minutes cracked right up, got it home, got my Dodge engine book and voltmeter. It was an 84 Dodge caravan, 4 cyl.; there was a motherboard inside the distributor for lack of better name. When it got hot it would crack, when it cooled down it made contact. The dealer shouldn't have found it in 20 minutes, took me 4 hours and a bunch of fancy words directed to Dodge.

[@markchidester6239]

Excellent video The variable resistor was awesome These electrical videos are my favorite Looking forward to the engine replacement series. That's my story and I'm sticking to it 👍

[@michaelknorr6825]

You have to respect the amount of testing he does confirm the issue, all the way through the process.

[@mikerobbins5049]

I am glad there are people out there that understand this stuff so my vehicles can get fixed properly. But I wish there were more like you and my auto tech guy because there are just to many shops out there that should just doing oil changes

[@williamfralick3656]

Thanks for the knowledge. Never would've looked there.

[@timtaylor7106]

Great tip on the A/F ratio logic,thanks

[@jeffreyevens2033]

Very thorough step by step diagnosis. Nice video, very informative!

[@miketeeveedub5779]

A couple of years ago I bought a Standard MAF for my Ford when trying to diagnose a P171/174 lean error. I immediately got a sensor failure message upon installation and subsequent drive cycle . It went away when I put the original Motorcraft MAF back in. I learned a valuable lesson that day. Even if the part is new, it can be crap. Thanks for reenforcing that message Eric - buy OE parts whenever possible folks!

[@s.j.5850]

Great video as usual. It would seem that in the race to become a go-to aftermarket supplier they are trying to cover all makes & models, but failing to get each variation of a part to be as good as the OEM. Your logical approach serves you well - keep up the excellent work!

[@4b131]

The variable resistor is one of my favorite tools. I don't use mine much but when I need it, it's gold.

[@eighthof8]

My '97 F-150 would constantly go into limp mode. Ford dealership said it's a bad head gasket. Didn't believe it. I purchased a new sensor from them. They sold me the wrong one and it smoked the temp gauge. Temp gauge no longer worked, but it solved the problem, no more limp mode.

[@slocavky]

Nice work Eric. Also you took a different way on the big road as you call it.. Nice to see a different part of the scenery around there...

[@ThunderbirdRocket]

Great 👍🏼 work ! I really enjoyed watching / learning how to do this repair .

[@curtw8827]

Love this channel, no need for paper floor mats.

[@leonardcrisci7254]

I’ve also learned from experience, at least for GM’s. You will not complete a drive cycle, unless you use the key to start. I was using my remote to start and I couldn’t complete a drive cycle and somebody told me no try using the key after it sat for eight hours.

[@freetolook3727]

When troubleshooting customers RV appliances, the first question I would ask is "What is it doing or not doing?". Always got a thoughtful concise and informative answer from the customer. They are your best source of info and always know simple facts like "When I turn on the thermostat, nothing happens", even though they don't know the technology behind it.

[@macdonaldsmotorworks]

that little potentiometer that comes in the AES wave connector kit is a go-to for me. I've had a number of situations like this one where new part doesn't solve the problem and I've been left scratching... further emphasizes that a known good, is good! Thanks as always Eric!

[@Mike_Engel]

Love you Videos Eric.... Thanks for making them and explaining your methods in troubleshooting

[@terryjackson2998]

As always, a wonderful informative video! Sincerely loved it!

[@technolucas3720]

Junk parts wasting everybody's time......great job figuring that out👍....still a learning experience

[@stevew9563]

Would love to see many more videos on Drive cycle monitors. Your viewers in CA would watch every one! Those are the bane of our existence in our state!! Thanks for the informative Vids!!

[@scottgm321]

I’ll never forget the car you worked on where the power steering pressure switch was bad and making the computer say the evap was bad. You may be able to do it but I can’t and don’t want to.

[@tpanther9567]

Good way to start a Sunday with SMA.

[@billrimmer5596]

This is a vid I will flag in my brain. Great thought process. Love any hints on drive cycle. I am always trying to pass cars for inspection. Good to know why and why not.

[@mikechiodetti4482]

The coolant temp diagnostics was spot on. A new GM sensor would have shown the difference. The vehicle sitting overnight proved that. I found graphing the cat monitor and watching the digital readout will work. My wife 06 Sorento proved that when I was testing the cat monitor. That one was intermittently working then it would "track" the front B2S1 sensor, continually doing this cycle. Good call on the CTS, unfortunately 2 bad cats will ruin a good day. Good one Mr. O!

[@tealbunny]

Junky Napa parts drive me crazy. simple radiator and fuel caps last week. Nice find Eric, way to fallow through.

[@jameslewis1175]

Hey man u got a lot of respect from me for the monolog at the end about not working for free.

[@arnoldviana525]

Very good video not to long, great diagnostics.

[@porkchop4604]

Eric, you must have attended a lot of Bizzares when you were a kid. When something doesn't respond as it should you always say "bizzare". Another great diag. Always learn a ton. Keep em comin.

[@josephgallagher3291]

your diagnostic, and knowledge skills are steller. i repaired heavy equipment and cranes from 1972 to 1996 cat dealer and fed shipyard. the era of NO computers. it was not important to know everything. but your succes depended on knowing where to get information. now that need is 100 fold. and you just hit it out of the park consistantly. kudos!!

[@jamesbruno5896]

Nice diag Eric! Thanks for sharing!

[@stevenreynolds2327]

Hi i'm Tom chevy Bodet, and we'll keep a light on for ya. 5.3 is rare in a TB, had one and loved it...till the AFM lifter collapsed.

[@douglaslamb8709]

Napa Napa Napa you’ve done it again 🫣 (not a sponsor) thanks Mr O another great video👏👏👏

[@rudimurga7034]

great video Thanks for sharing love to watch your videos I have a GM Sonoma 91 4x4 has 4.3L I know it's old but I like fixing it had it for 6 months

[@kyletuttle9064]

Cool diag and monitor lesson Eric.thanks for sharing .

[@mikeboring1293]

Great detective work Mr O.

[@dprrn]

watching the O2 data showing it test the cats in real time was neat, reminds me of when I had a cat replaced on a buick to rid the 0420 code. few months later the light was back for the same thing. ended up watching the data while I gave er the beans and the rear sensor settled down. I just let it clear the light on it's own to be sure it was cleared.

[@randyhawke5341]

Like I've heard you say before: "NEW" stands for Never Ever Worked.... So true...

[@justinlanglais9825]

Great job as always Eric ! 👍🏼

[@Mac-mu9cs]

Always fun when you fix issues and now a full drive cycle runs and finds even more issues. Especially evap

[@danielesilvaggi]

Woe!!! you almost hit that guy lol. Dam parts vendors. Great find and video. Thank you Eric.

[@bazw1685]

Love these videos of proving that new doesn't mean it's good 🤙 great diag and hopefully another happy customer, all the best 💙

[@richardthomas1743]

HEY! Good morning Eric! Happy Sunday and thumbs UP!!

[@davidmcclain5180]

Great information and diagnosis on this one. Great job.

[@mark_osborne]

Fantastic. I was really wondering how a circuit could fail in such a way as to have "too little resistance"...ha !

[@mjh123crh]

Eric O, I learned a very long time ago that brand new does not mean brand good, keep on keeping on!!!

[@wildman9364]

I had that same problem with my ford 12 or so years ago junk new napa sensors. got one from the ford dealer worked haha so from then on I dont use any aftermarket ones. crazy how picky the specs for calibration are another great video from you man cheers

[@markmalikowski4971]

Another excellent diagnosis. It's unfortunate that the converters are junk. Hopefully the customer understands what happened,