Service Stabilitrak / Gauges Not Working / Stalling+Hesitation... ECM Issue?

[evonschu]

Hey all. A few months back I was on my way home and just before I got to my neighborhood all the gauges stopped working, the car started backfiring badly, nearly stalled and ran very poorly until I limped home. I had experienced similar issues on my old Colorado when it was under warranty and they had found the ECM had loose pins in the harnesses. On a hunch I removed the harnesses and reseat them from the ECM and also let the car sit for about an hour. After that fired it up and it drove fine and didn’t have the issue again. I think I had this happen once at the gas station a long time ago too and I just let it sit for about 10 mins then tried again and it was fine.

Today, however it did the same thing after I filled up at the gas station. Had a real hard time starting up like the battery was dead (its not) and then when it did fire up none of the gauges worked, it said service stabilitrak, and it stalled. I couldn’t start it afterwards (I tried 3 times for about 5 secs separated by about 2 min each as to not overheat the starter motor). I popped the hood and was gonna try my ECM harness reseat and noticed the ECM was really HOT. I checked all the ECM fuses and they were fine and reseated the harnesses. Tried to start and still no dice. So I let it sit for about 15 mins while I looked up anything I could find on the forums of similar issues people have had. Guess some people have had serious issues with the ECM failing even at like 6000 miles?


After 15 mins of looking at various posts with the hood open, I tried to crank it over again and it hesitated a little and then fired up, gauges working normal, idling like there’s no issue. Drove home and it was fine.

I was thinking of just ordering a new ECM off rock auto as they are only about $220 and having the shop that did my tune in the area re-flash if necessary? I doubt the dealer would warranty this since A) its so heavily modified and B) the factory warranty is up (past 5 years), but will call them tomorrow to see for sure.

The fact the gauges don’t work when this happens and that its getting abnormally hot totally seems like a problem with that part. Any other things to check? Can't remember if relocated any ground wires when I did the Rotofab so gonna go check that first. Specs on Z are in my sig. Open to any suggestions or experiences. What all needs to be reprogrammed if you replace the ECM? Tune? Keys? etc.

Thanks

Thanks.

[evonschu]

Just checked and ground wire was never touched on rotofab install. Still secured tightly on original post and not pinched in any way. Even after sitting in garage off for about 45 mins the ECM is still too hot to touch...

[SSBUSDRVR]

Had similar symptoms except for ECU(really didn't go near it though to check) 3 days ago but wasn't ECU was Battery.(noticed you said Bat good) Car barely cranked over (Hot Day here) then No Tach, Autometer DashControl HUD display quit working. Started to misfire. Service Stabiltrak. Bad Battery Wasn't taking charge.Replaced Battery. Been fine since. Happened a few months back and charged the Battery. Should have replaced it then at almost 4 years old.Hope you get issue straightened out.

[evonschu]

Thanks I'll check that out too. I know it was sitting at a shop for a while and the battery died while I was moving houses. They had to trickle charge it. But i think that might be from a slow leak in amp for subs. I just dont get why this would happen once in the middle of driving and also at the gas station when i had been driving 30 mins straight prior. Also the fact that I waited 15 mins or so then it cranked over fine seemed suspicious too.

[Syvert]

Originally Posted by evonschu

Thanks I'll check that out too. I know it was sitting at a shop for a while and the battery died while I was moving houses. They had to trickle charge it. But i think that might be from a slow leak in amp for subs. I just dont get why this would happen once in the middle of driving and also at the gas station when i had been driving 30 mins straight prior. Also the fact that I waited 15 mins or so then it cranked over fine seemed suspicious too.

I had my ECM replaced yesteday because of the issues you mention above, all dial gauge was dead and no comminication with diagnostic tool on the ECM, when the replacement was done without re-learn the ECM all gauge was up and running,fuel gauge was also ok. After this there is some programming to do.keys, immobilizer,throttlebody and ect.But it is not to bad. 1-2 hours i would assume.Best thing is to get it diagnosed.Stabilitrak message in display is more like a common message and do not tell you what the problem is. But mine is original except CAI intake,I SEE your ZL1 are quite modified so i guess you cant use the original tune/calibration Mine has only 2500 Miles on it. Must be some kind of weekness in this ECM.By the way, I send the ECM to a company to fault find the ECM and they found the unit was missing 5 volt internally in the ECM unit.

[SynergyGreenSS]

I had similar issues, I changed the battery and that helped temporarily but soon the symptoms came back. Oddly enough, after having the car tuned by a different person, the issue hasn’t come back

[nolandkropf]

Im having the same problem. I would like a few more opinions out there. My car doesnt start the 1st time on a cold start. After driving for awhile when the car is hot, shut off, and wont restart in 5 min. Pop the hood, and repeat, starts up. I was thinking it was a heat soaking issue, and had a shop add an additional ground wire. still an issue. Heavily modified.

[evonschu]

So got the new ECM, got it programmed with the VIN number, and the exact tune I had downloaded from old ECM re-flashed back on new one. Guess there's some immobilizer stuff that needs to be programmed in as well as the keys I'm assuming as we couldn't get the vehicle started on new ECM. We tried disabling VATS and some key reprogramming techniques that did not work. He suggested I bring it to dealer to get all that programmed in as he didn't have any way to do it himself.

Is there anyone on here that is in a similar situation where they replaced a Tuned ECM and what exact process they went through to get it up and running? Read through a few threads on here and seeing mixed results... I hate going to the dealer for anything.

[evonschu]

So update and the process needed for anyone else going through this:
* Installed new ECM and flashed custom tune on.
* Put in old failing ECM and bought vehicle to dealer.
* Dealer WAS able to program the keys, immobilizer, and CASE relearn without having to flash the ECM back to stock.
* Done, OLD ECM WILL NOT work in vehicle. You can't have 2 ECM's as the rest of the modules in the car are tied to the ECM that's installed and only the dealer can program this.


Hoping to god I won't have to go through this again. Contemplating putting a fan on the heatsink for the ECM just to be sure it stays cool. Hopefully this thread will be helpful to others on here that find themselves in similar situation.

[newz]

evonschu Thanks for the ECM info and glad you resolved the issue. Also thanks for the dealer service info.

[evonschu]

So noticed yesterday it was hesitating a little more than usual starting up. Then in the evening did the exact same thing that happened in the gas station where it'd spend several seconds trying to turn over and then fire up in sort of a limp mode with the gauges not working, service stabilitrak, CEL, etc like before. Replaced battery and now is running fine. Walmart had 800CCA, 1000CA Everstart maxx H7 batteries for $150. Have used these batteries before with good results.

Not sure if both the ECM and battery were bad, but its running well now. Still think there might have been something going on with the ECM by how hot it was getting and the fact that it went into a similar limp mode in the middle of driving way back. Shoulda probably tried the battery first like SSBUSDRVR suggested. Oh well. Maybe I'll sell the used ECM on ebay. Its probably better as they did a CASE relearn on the new ECM anyway since they hit the rev limiter on the relearn and the redline is at 7k now. It certainly seems like its running better than ever with these items replaced so I'm going to roll with that.

I've had a lot of issues with getting the tuning right on all these mods and was starting to feel like the car is a dam unicorn. Hoping this will be the end of the problems for a while and I can enjoy the ride again. Still continues to draw attention everywhere I go. Had half the dealership out asking me questions about it and the upgrades when I picked it up from the ECM programming. Double edged sword.

[evonschu]

So just had this happen again today. Been fine for over a month then randomly stutters for about 5-10 seconds before fires up like battery is low, service stabiltrak, half the gauges not working, etc. I got a P0335 code for crankshaft position sensor so ordered that from rockauto since its $12. But I doubt that will fix. If I wait 10-30 mins and try and fire it up again, everything is fine like nothing happened. God help me if its some sort of wiring issue with the harness to the PCM.


One thing I'm noticing is that this always seems to happen only when I've been driving for a while, park it, then not long after (~5 mins) fire it up again. I've yet to see it happen on cold start. Like fueling up for gas would be a perfect example. Any other ideas would be helpful. As above thread states, already replaced battery and ECM, reflashed tune, CASE relearn etc. Crankshaft Position Sensor in mail so will try that.

[SynergyGreenSS]

When I had the same issue, I replaced my battery and that fixed it temporarily and it came back pretty quickly. As I believe I stated before, what solved it for me was having it tuned by a more knowledgeable shop. My car had this issue any time I would run it hard and it got hot. Gas stations were always scary lol. The original tune was done by a shop that I later found out was not so great. Once I got it done by someone else the issue seemed to be resolved. I would have the tune looked at by some other shop

[evonschu]

Ok I emailed the shop in town I work with. I am friends with the owner and he is extremely adept at tuning, will get his input. He is basically working with a base tune done by JDP who is also definitely reputable. I know we were trying to battle a different cold start issue a ways back as well as an issue with timing being pulled when accelerating from 2-3k and that was about the time this started, so that might be related. Those issues were resolved though with a few tweaks to the tune and new plugs.



I drove to work today, then killed it, fired it back up no problems. Did this 3 times, no issues. So it definitely is intermittent. I didn't drive hard at all though and its a lot cooler outside than it was omw home yesterday.



It possible its the starter on its way out?