GM Truck Stall, No-crank, No-start Case Study - Part1 (Trailblazer 4.2)
ฝัง
- เผยแพร่เมื่อ 28 ก.ค. 2018
- Here we have a 2002 Chevy Trailblazer that stalled out on the owner, and is now a no-crank, no-start situation.
After throwing a few parts at it (starter relay, ignition switch etc), the owner called me in for a diagnosis.
Let's just say good thing he did, because no amount of parts cannon firing would have fixed this thing, short of buying a new truck!!
Enjoy!
Ivan - ยานยนต์และพาหนะ
![[LIVE] ใครคุยเรื่องบอล "พ่องตาย" #คุยให้เด็กมันฟัง EP.43 (13/7/67)](http://i.ytimg.com/vi/8bHYL8RuBqs/mqdefault.jpg)
![แฉ [2/4] 11 ก.ค. 67 ‘ขวัญ อุษามณี’ เผยความจริง 16 ปีที่แล้วเกิดอะไรขึ้น? | GMM25](http://i.ytimg.com/vi/K4pXnUiObbk/mqdefault.jpg)
Always looking forward to new material by Pine Hollow! Great work, Ivan!
Ivan
Great video and case study. Looking forward to part 2.
Thank you and God bless
Paul
Time to call Eric O
SMA
The 2 of you can figure it out in no time.
I own 2 trailblazers and love when you and Eric O do repairs on them.
Looking forward to Part 2
This is a good one Ivan. Looking forward to the next step. Thanks!
Waiting for you to figure it out!!! My 2003 Silverado was doing the same thing for awhile, but would start working without doing anything. I am leaning towards immobilizer system. Great videos!
Very interesting, as are virtually all of your electro-mechanical mysteries Ivan. Looking forward to the solution.
In our neck of the woods you know what I'm gonna say, bad ground, oxidation, corrosion, I'd start looking at connectors and wiggling the wires, excellent video Ivan
Fantastic always looking forward to these videos
I think is a PCM power feed issue, can't wait to watch part 2, thank you!
It's been a while man! Give us more of these (no start) interesting fixes
very interesting case study , cannot wait
It's nice sitting back and watching Ivan do all the work especially after being around this crap all week. Great video Ivan can't wait till part two. P.S. GOT MY POPCORN AND SODA WATER.
Thanks for the comment, Tracy....I promise you won't have to wait too long for part 2 haha
Pine Hollow Auto Diagnostics Haha.
Hahaha
Haha love that Keith tap test, sure is looking like source voltage/ground issue to the pcm. Since many components are being affected. Especially that throttle plate not passing 33 percent, it should've gone all the way if you floored it. Great video Ivan, looking forward to part 2!
Possibly, but I know my 2002 Saab which has heavy GM influence (GM owned them at this point and they were full swing into using the GM parts pin) is fly by wire with a "limp home mode" that deactivates the fly by wire feature and reverts to an actual cable attached to the throttle pedal. Basically if the car is off when you step on the gas and the car is off it shows you as going to about 35% (which it is, that's the feature of the limp home mode). Since this is the same time I could see the Trailblazer having a similar throttle body. If the car was on and running and you rev it then the solenoid for the fly by wire is active and it'll show you the percentage the throttle is actually opening.
Jesse C interesting point. The main reason I'm leaning toward a pcm power/ground supply issue is because the throttle body is not the only symptom. Every other component he actively tested had similar symptoms, lack of supply voltage. This particular vehicle has no cable backup. But interesting point nonetheless Jesse.👍
It's almost got to be a bad ground great video ivan really interesting
As the previous owner of one of these the first thing I would suspect is a bad ignition switch - it's a very common failure on these. Now I will watch the video :)
OMG! I Hate waiting! Lol! Fascinating stuff. Thanks for grabbing the camera Ivan!
Wrench Spinner Agree "NO MORE WAITING"!!!! LOL
When I saw "No codes" I instantly switched on the camera ;)
Hello Ivan
This one is fun. For sure, checking for powers and grounds at the PCM is next.
Coming up in Part 2 :)
Great Video Ivan, I would try the cooling fans w/ bi-directional controls. I would find a hot sensor in the run position (body/eng grd) and check the grd Mill amp value. Then I would look for a ECU pull down sensor and look at its value....Hey what about a V_REF check also. but this is a great video,, I like the built in parts swap throat slit key holder from "Doreknob parts mismanufacturer" I bet...anyway good luck and hope to see the final result soon. Mike
lol hurry with the fix before i build a fire under mine,thanks for the great videos
I`d be looking for broken ground braid from engine to chassis, all previous troubleshooting was right on.Keep up the videos, between you and Eric, you two are the best,too bad your are not in Shelton, Ct.
What a cliffhanger! Lol I was just about to grab a drink 😂 I'm betting a bad ground. I'm sure by now you have it fixed and shipped on its merry way 😉
Save your drink for Part 2 Niamh! It's almost as exciting as a BMW diagnosis ;)
Everyone thought it was our brand new faulty ignition switch. Not this time. Dorman wins again!
Well that was only HALF the problem haha!
@@PineHollowAutoDiagnostics And Dorman never wins!!!! 🤣
I'm leaning towards a high-resistance bad ground at this point. My theory for no codes being set is that the bad ground can probably pass a small amount of current at all times (let's say 8 milliamps). Because the PCM can only read high and low voltage signals, the circuit is technically complete, but can't operate the higher current draw from the relay. The spikes on the vent solenoid control also lead me to believe the bad ground may be able to pass slightly more current for a very short time.
That vent solenoid was the weirdest thing I've seen. Usually either it works or it doesn't!
I think you are on the right track checking the ground circuit would be my next step.
basics first
I agree powers and grounds to start with (no pun intended) and work from there.
Very interesting Ivan..who the heck knows well you DO..lol, wild guess based on what ive seen here ground or computer, ill wait for part2 :)
This is a nice one. I like it!
This reminds me of a Cobalt PCM that had internal ground traces fried due to being mounted next to the + battery terminal. Since the PCMs' case was a floating ground, the interim fix is to ground the case to the chassis. I didn't see if your PCM mounts to chassis ground but it is in the right spot to be grazed by jumper cables.
Nice! I once had weird issues and they were because all electrolytic capacitors started leaking and made a mess in the ECU.
I would send a ground directly to the ECU. If the problem persists, open the ECU and check for corrosion/cap leaking. If you are lucky, that truck is old enough and it will not be filled with epoxy.
really cool case study. we don't guess. we test.
Bless BBB Industries for their great service
Agreed.
@@PineHollowAutoDiagnostics
No
@@PineHollowAutoDiagnostics
a
Most interesting and quite possibly pertinent to me as this is my main vehicle.
Hi Eric, THANK YOU for those mini files! I will put them to good use soon :)
You are welcome Ivan, hopefully they are not too short to be useful.
This one is interesting and I'll be back for the second part to see what's up.
See ya in Part 2, Wyatt!
When you were testing the crank fuse (No. 17 - 10A) you had your other test light lead on the positive as I could see...it needs to be on the GND terminal! You are checking for positive against the positive, of course you are going to get 0V. Most likely it is a rusty ground connection. The purge solenoid draws very little, so the power for it most likely fed through the electronic circuit of some other relay, module or something else. One tip...as you select fuel pump ON, remove the fuel pump relay and check the power with DDM, then use a test light to test power (DMM have very very high internal resistances and might give you 12V, but the light will not be on). Typically when there is ground of +12V oxidized, corroded or even broken.
Hi Ivan, Well hind site suggests that since you were troubleshooting with a defective ignition switch that maybe you should start over and repeat your process. This of course was never a start problem but a stop problem as the car stopped on its own. The fact the there is no fuel pump prime which normally only requires the RUN position suggests that this is not a start circuit problem.(however you would eventually have to fix the ignition switch problem created by previous part swapping). What does it take to get the fuel pump running. Yes the PCM and a good RUN circuit. This car has two 5 volt reference sources, 5 volt ref 1 and 5 volt ref 2. I would chase the PCM power and grounds as well as all 5 volt reference sources as you have suggested. Look for other sensors that are not working and what maybe in common among them. Not saying this one is easy. Looking forward to your results. Thanks for taking us along with you.
I would Check the immobilizer...security system can be fualty...also i agree with u on checking for power an grounds at ecm/pcm...that never hurts
Drews Auto exactly. It sounded like the immobilizer was activated when he could attempt a crank. Those wonky valves is making me rethink it tho.
gut says ground. I agree with Josh.The crap I work on switch grounds- bad crimp or smoked trace. Even had small sensor cables wire tied too tight and break an inside wire.
great video brother : )
Your logic is, as always, solid. At this point I would be doing insulation and continuity tests on my feeds and grounds on the ecu. A test under load conditions would show any milivolts dropped. Big fan of power probe 4 and it would be getting a good workout on this job! As a matter of course I also do a functional test of the relays under load conditions with my relay tester. A check of the integrity of the loom to ecu connector is also required?
Great suggestions, Andrew! Except you don't need a fancy PP4...test light is more fool-proof :)
Pine Hollow Auto Diagnostics you are very right. I still use test lights but I was given one by a customer who bought it on a whim and never used it, don't think he knew how! The convenience it offers is very good. Being able to power up components and the other tests it can do make you feel the love for it. It can reach all around vehicles and aircraft and is easy to use and has a built in torch! It has become my go to tool for first diagnosis. Expensive but worth it,better if somebody else pays for it!
Huge thank you!!
In the old days when the dash went blank when in start mode, we'd get out push down and wiggle on one or more battery terminals. Sometimes we'd have to actually clean the terminals. Broken wire under somewhere. in this case. It happened suddenly. Maybe some part of the computer died. It is an older truck so corrosion. Also as he came to a stop maybe inertia pulled on a damaged part of the harness causing it to break or lay up against a ground.
Time to call Father Karras LOL!!!!
Looking forward to part 2.
If I had to guess,,,, I'd put my money on green crusties causing intermittent PCM ground.
cheers Ivan my guess half powered PCM!
Very interesting theory! You will see in Part 2 ;)
cheers Ivan look forward to it! How's the new job going? have they made u the MD yet they should cause your a genius son!!! cheers sandy
Perfect Illustration why NOT to use the "Parts Cannon"! Not only can a misdiagnosis lead to changing unnecessary parts (ignition switch), but you can create probems for yourself (or your mechanic) by injecting new problems with substandard aftermarket parts. I guess those dorman parts are "born broken" (it's a real time-saver). Just assume the're worse than used OE, and you'd be correct a fair percentage of the time!
haywire17 Totally agree aftermarket parts are crap. Give me OE parts anyday.
Why do you pick on those Dorman parts so much? They can't help that they were born a not working part!! They can desire to be anything they want, and most Dorman DREAMERS identify as top quality and functional! That's not somethings for you to make fun of, discriminate against, or bully those poor parts! We all need to learn to accept inferior parts as acceptable, and make them feel wanted and loved, but NOOOOOO!! Everyone just throws those non working parts away, like they were trash!! There is no "working" or "not working" among parts!! They are all just parts, and should be treated equally!! PARTS EQUALITY!! EQUAL PRICE FOR ALL PARTS!! All parts should be treated the exact same way! With love, honor, and respect!
roadkill5333 LMAO NOT IN MY WORLD!!!=_=
Tracy Diller...LOL!!!
roadkill5333
there is your head aches when you support dorman, pist off customer after they loose there day of work , paid tow trucks and by the way that day you did not count on come back you shop was full of good paid work had to go today , you promise to your customer , are you happy with those scenarios ?
Hey Ivan big fan of your videos, I was wondering how you made that custom test light? It seems to be pretty convenient!
I feel u , I feel the same way sometimes
Are the other not working circuits also ground side switched?
Yup Dan, I think all the ones I tried are ground-side switched... ;)
Wow that more than super interesting! I think you don't have the check engine light on the dash at all, even right after turning the key to run. There's just CHECK GAUGES and CHECK ENG OIL. I think that gives a clue. I guess it's a blown fuse or something, that feeds a part of the ECM. Or the ECM itself got bad. It's 16 years old if it is original, could have gone bad after that long.
All it needs is a shot of brake clean,a quick call to the tow company and title,scrap it...its a trailblazer, there junk anyway. Ivan thanks for the brain teaser. Iam thinking a ground issue
hi, love your vids, wish they were 3hrs long, I probably would have diagnostic overload..
LOL I try to keep them to 20 minutes or so...some people get bored!
Love your videos. 5 v ref, fuel pressure maybe
usually they make the relay foolproof. the pins look identical on your starter relay, so there is nothing preventing you from putting it in backwards.
interesting, thank you.
I'm the family "mechanic"! My sister-in-law was driving here 07 trail blazer home and it died at the stop sign by here house. It wouldnt spin over even though the battery isn't dead. The dash blanks out when you try to crank it. Sounds exactly the same, I will check it out tomorrow! I hope it's the exact same when I get there, thanks for posting!
Cool! Good luck!
@@PineHollowAutoDiagnostics it went from bad to worst case scenario! The 125 amp starter fuse was blown and she said it sounded like a diesel for about a week getting louder every day. I couldn't turn the engine over with a pull handle, I think the only reason it lasted as long as it did is because her commute was about a mile each way. I still think that speaks loudly of Chevrolet, it ran for way longer than I would have thought it would with no oil pressure.
WOW...well at least the truck gave her a fair warning haha
And,,,,,, I guess I’m not the ONLY ONE that gets this kind of repair. 🤔🤔🤔🤔😧😧😧😧😧🤯🤯🤯🤯 lol
After watching the first half of the video, I was about to comment that I had the same problem on the same vehicle two days ago, but a new ignition switch fixed the problem in my case. After I diagnosed the bad switch, I realized the vehicle was equipped with an aftermarket remote starter, the vehicle would start with it while the bad switch was still connected. So it didn't get as interesting as your specimen. I'm thinking you are correct in pursuing the bad ground issue, having no bi-directional control and no pcm supplied ground at the relay. Once you solve the problem, the relay itself may turn out to be bad, maybe not but it seems that would be your luck.
First to check. Fuse to PCM 20 amp Then pin 87 from relay plug the relay back in and jump wire to plus side to battery. Will start the truck right up with key turned on. That’ll get ya out of a jam
Nice like the way you figure it out, could it be a weak power supply to the ecu!
Wouldn't it help if checking for spark, fuel or injection pulse while manually cranking?just to add more pieces to the puzzle. I know the feeling when you find a problem that is not the problem. Intresting case Ivan waiting for part 2
I had a really wonky problem with a chevy trailblazer, where the dash lit up but a few lights were missing out on the dash. No crank no start, bypassing the starter relay with ignition set to on, the vehicle would start and stall. All fuses good and power feeds good all neutral safety switches good. Turned out it was a loose screw holding in the fuse box (under the rear seat driver's side) making it so the BCM wasn't getting power correctly. Tightening the screw holding the fuse box. Bam started right up all dash lights perfect, ran fine. Maybe this is a similar problem??
Knowing GM products of this vintage, my money is on a wiring problem. Probably a ground issue , since unrelated circuits are affected.
Can't wait for Part 2 - the suspense is killing me! 😁 👍
Keep up the great work. Why do you have 2 bulbs for uour test light?
Wonder if under the fuses and relays under the hood. If there is a connection issue, either due to green crusties or broken/loose wire.
Bad computer ground (s)? I didn't see a security light flashing. DIY substituted another computer?
check the ground by the body mount behind the drivers or passenger tire I forget. Bunch of grounds there on all the chevy trucks and they rot
going thru the exact same thing with 03 silverado 4.3,suspected bad pcm done swap and same exact thing would be nice to have a Eric O. around here in VA. the only different problem i have is no comm with pcm before and after swap.
Uh oh...yes Part 2 might help you out :)
Best guess. Simplest thing that screws up the most components - a bad ground that is easy to miss but critical to vehicle operations. Start with a strong flashlight and do a visual inspection of underhood and lower engine/transmission wiring and grounding points, as well as check for rodent damage of wires near fuel pump.
Ugh I hate getting my hands dirty ;)
Check the wiring under the fuse box for green crusties/ broken wire. TheReaper!
Nice
i would check powers and grounds at the ecm, and just for shits and giggles i would verify that the fuse junction block under the hood is good, we change them all the time on the chevy and gmc cutaway van/school buses for crazy ass weird problems that will make you pull your hair out, either way i can't wait for the out come
The thumbnail looks like you're crying or about to cry....😁😂
I'm guessing, key word is guessing, that half of the PCM is missing a power feed or a ground. I think when in crank the power through crank fuse to pcm is what is what tells pcm to ground the circuit for starter.
Perhaps the security light goes out, but that circuit still isnt letting the bcm start... like a stuck relay?
Bad ground on ECM. Case ground may fix it.
Ivan The alarm system is what cut it off in the key there a rezister ! The reson why it go crazy is the arlam system is stoping you i know there no codes but i get the hint i am right Just for the heck of it try to reprogram the key with the new I/S before you go ball pulling out your hair chaseing a gost !
Well there would be a code if PCM is not happy with the key!!
I know this might sound crazy did you try giving the car a jump start? Also, did you check tsb and or common solutions with the car?
I wish that you lived in my area. Around here, car mechanics are afraid to attempt diagnoses of electrical problems. They won't even try a parasitic draw test.
Ignorance is the leading cause of fear lol
My gut says ground issues. Especially since it happened while travelling. Last bump finished it?
There is a also a 5v feed that feeds the oil pressure sensor. If that sensor loses its signal it will kill the engine and will not allow it to start
As Eric O would say , a case of the green crusties on the PCM connections , just my guess .
Same exact thing happened to my daughters 03 corrola except hers would run when starter jumped with ignition on so I just got wired a push button for start and all is well lol spent 2 days on it
I pulled the starter relay, ran two wires to the start side and ground side, placed relay back on to keep wires from falling out. Then ran the wires back to a push button as you did. Turn key on hit start button it starts.
NOTE: This vehicle is a 2004 Cadillac cts that was taken to the GM dealership and they were unable to find the problem, two days they tried and was unable ti diagnose the problem. Luckily I complained a great deal and there was no charge. My son drives it to work everyday and so far so good after several months.
Joseph M great job joe yeah we gotta do what we gotta do and it works 👍🏻
Indeed we do. Thanks,
Are there any poor grounds on the chassis between the PCM and the Starter?
Hey Ivan whats up brother.. I'm following from the deep south here in Memphis Tn.. Man this one has me scratching my head u have pretty much covered all the bases so your findings will most definitely be worth it.. To me its looking like a bad ground some where but where is the question.. Pull the computer my friend have a look at connections and wire integrity,are there any green crudies, possible rodent damage,.. Or worse case scenario this thing is in need of a Computer..
All good suggestions! Part 2 will have some answers :)
Pine Hollow Auto Diagnostics .. Thanks my friend for sharing good luck ... I'm in your corner man u got this, school is in for me cnt wait to see part2 and what actual issues was the cause..
I would test power to the fuses and the PCM and check inertia switch for a start...
It absolutely did not need an Ignition switch, I don't even have to finish your video to see that it's BCM related issue, The power train control module relay has to be hot as well as the starter relay and it must remain on until the vehicle is turned off The Crank run relay is hot as well which if I'm not mistaken off the top of my head Also controls the PCM relay different circuits same trigger On the hot side now the ground is controlled by the BCM underneath the Ignition there. Which also goes through your park neutral safety switch and I believe the transmission range sensor is well Both of them aren't up to par you'll get no ground as well as a communications issue on the BCM will also give you a no ground no start no crank situation
Guess: Something wrong at the computer connections in the engine bay (corrosion or pin fitment), or something wrong with the anti-theft key. It seems like with SMA there's always an aftermarket part that's been removed (like remote start), or some previous crash damage that wasn't stated by owner that ends up being the cause. Really, I don't know.
Perhaps, connect a cable to the Battery Neg, and do some continuity checks at the PCM earths.
Could be a bad ground, it being a GM product could even be the old green crusties.
Pull a wiring diagram, and locate all the grounds. Perform a visual inspection on them first, and the connectors going to the computer
What do I think .. look for green crusties?
Is your wireing diagrams free or do you pay and if so how much do you pay if you dont mind me asking
Something's going to be corroded, melted, or chewed through. Or not. :)
My guess is a bad ground connection to the PCM. The PCM generally has many ground connections, but they may not all tie together inside the PCM circuitry, and may actually serve different PCM functions. My thought is that the PCM's "brain" has a good ground (able to communicate), but that one of the PCM's I/O sections that actually drive external loads (like the crank relay) has lost its path to ground.
Look for green pus in connectors, then check continuity to ground on ALL the connector pins that are supposed to go to chassis ground. Hopefully all the PCM powers/grounds are available on a single wiring diagram, or you will have a lot of hunting to find them all.
Great suggestions, Bob! Check out the PCM diagram for this vehicle. There is in fact only one main ground....usually there are more!
Try checking powers grounds to pcm perhaps half of pcm is out have you got all ref voltages under a crank condition same with grounds
Never had a half-live PCM with no codes but that is a great thing to check :)
Hey Ivan. That is weird looking truck, lol. It sure sounds like a bad ground issue. Maybe crusty old wire!! The pcm is partially communicating with some ground already connected. But not all ground for the BCM and others. That's my guess!!!
Hey Josh, I was thinking bad ground too, especially with that random vent solenoid activation haha
I know this is a old idea but I would check the battery ground from the battery to the frame the best way to do this is us a good ground wire to test the battery ground
PCM fuse, the fuel pump got too hot maybe cause of low fuel, or the exhaust has a leak near the fuel tank. Seen that before on a 07 blazer.
So what was the problem with it ?
I have one doing that same thing rite now, please help !
Did you check to see if the battery is maintaining voltage while you crank, that will be another way at looking at it.
Would any codes appear in memory but not actively shown? I was just wondering if it had a bad ground could it generate a code, but then with the bad ground the computer thinks the battery cable was disconnected and doesn't actively show it. However, certain code readers can see old codes that have been cleared. Just wondering if it also can't generate a code because it needs that same ground to do that.
not sure...ususally PCM is either alive or dead, unless the "Keep Alive" power is missing. But it usually stores a code for that too lol
how do you like the Verus Pro? Trying to decide between a used Verus on ebay or a new Autel or OTC.
I love my Verus Pro! Depends on if you want a scope. Autel would be more versatile with the Euros. Verus is boss with older cars including pre-OBD-II. Hope that helps :)