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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[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.

[frankvucolo]

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!

[wyattoneable]

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

[Whyismytacoblue]

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!

[clintprice]

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

[steveb]

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

[mrkttrdr]

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

[arniebriscoe]

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.

[JackdeDuCoeur]

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

[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 Youtube for all this hard work!

[Robalo-]

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!

[typingnow]

I just had to post that I think this guy is the most brilliant car mechanic on YouTube. 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.

[KC-vpwn]

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!

[TheRallyCoop]

For some reason GM does -38 while other manufacturers do -40.

Here is the question.
Is it Farenheigh or Celsius.

The answer is both.

-40c is equal to -40f.

This is why that value was chosen by the society of automotive engineers to give a diagnostic direction for open circuits for all temperature sensors on the car, regardless of the manufacturer.

Excellent video as always!

[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.

[rik]

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).

[DIYDaveOK]

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

[edwardsmith]

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.

[vanceblosser]

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!

[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 .