Weird intermittent problem
Thread Starter
Intermediate
Joined: Nov 2021
Posts: 29
Likes: 3
From: St. George UT
Weird intermittent problem
Wired should be weird. But maybe wired works too.
At a 2 day PCA track event at Spring Mountain, first day no problems after 2 hours of track time. Second day start the car at the hotel and get numerous warning lights. No power steering, no ESC, no traction control, no Edifferential, and a restraint system light and engine check light. Disconnected the battery and waited about 10 minutes. On restart, everything cleared except the engine check light. Drove the car to Ron Fellows maintenance area and a mechanic offered to read out and print 4 pages of code information. He also cleared the check engine light. I was able to do my first session with no problems. Started the engine for the second session and lots of lights again but they cleared themselves after about 10 seconds. Second session had no issues at all. Very very windy so left the track after these 2 sessions and drove 3 hours home with no problems.
Has anyone else experienced anything like this ??
Thanks
At a 2 day PCA track event at Spring Mountain, first day no problems after 2 hours of track time. Second day start the car at the hotel and get numerous warning lights. No power steering, no ESC, no traction control, no Edifferential, and a restraint system light and engine check light. Disconnected the battery and waited about 10 minutes. On restart, everything cleared except the engine check light. Drove the car to Ron Fellows maintenance area and a mechanic offered to read out and print 4 pages of code information. He also cleared the check engine light. I was able to do my first session with no problems. Started the engine for the second session and lots of lights again but they cleared themselves after about 10 seconds. Second session had no issues at all. Very very windy so left the track after these 2 sessions and drove 3 hours home with no problems.
Has anyone else experienced anything like this ??
Thanks
Thread Starter
Intermediate
Joined: Nov 2021
Posts: 29
Likes: 3
From: St. George UT
It’s almost all lost communication to various control modules. Brake system control module, engine control module, power steering module, transmission control module, ESC module, restraint control module. Car goes to dealer next week and mechanic will have all this info. I was just curious if this is a common problem. I have Alldata service subscription which includes the various technical service bulletins and I don’t see any that relate to my problem.
Moderator
Joined: Dec 2002
Posts: 40,881
Likes: 4,330
From: Lakewood Ranch, FL
It’s almost all lost communication to various control modules. Brake system control module, engine control module, power steering module, transmission control module, ESC module, restraint control module. Car goes to dealer next week and mechanic will have all this info. I was just curious if this is a common problem. I have Alldata service subscription which includes the various technical service bulletins and I don’t see any that relate to my problem.
Thread Starter
Intermediate
Joined: Nov 2021
Posts: 29
Likes: 3
From: St. George UT
C8 has been at the dealer for a week and a half. Dealer working with GM technical and still haven’t found the problem. I’m taking the car back and going to try to get a lot of cycles on it in hopes that the problem comes on steady. Car never faulted at dealer during checks. We’re suspecting a loose connection but there are many possibilities.
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Melting Slicks
Joined: Aug 2018
Posts: 2,780
Likes: 3,103
Electrical issues are common and can be very difficult to diagnose. There are so many modules and many times they fail intermittently.
Drifting
Joined: Aug 2019
Posts: 1,285
Likes: 647
Have a 21 Tahoe. Couple dealer trips right off the bat for a week at a time. Finally engineers diagnostic a module in the back would not shut down and kept trying to talk to the main computer draining the battery. Had to pull most of the rear interior to get to and replace. NEVER another problem.
Race Director
Joined: Nov 2004
Posts: 15,678
Likes: 1,097
From: birmingham Alabama
St. Jude Donor '09 and '13
DCM modules are reeking havoc with all the new cars. I work for Toyota, and have several models with the DCM’s draining batteries. We have reprogramming fixes.
Thread Starter
Intermediate
Joined: Nov 2021
Posts: 29
Likes: 3
From: St. George UT
I didn’t have any problems with the C8 for a few weeks after the dealer stay. Then I did a 3 day track event at Spring Mountain. On the third day, exactly the same thing happened with many modules on can bus 1 not communicating with the serial data gateway module. Disconnecting the battery didn’t help. After several start tries over about an hour, everything started working again. Seems like this only happens after a track day. Car is scheduled for another try at the dealer. I’ve studied the wiring diagram in depth and there are so many places that could cause the problem. I guess we won’t know what is causing it until it fails completely.
Feel free to offer suggestions.
Feel free to offer suggestions.
Safety Car
Joined: Nov 2021
Posts: 4,309
Likes: 3,829
From: Northern Illinois
I talked to a GM engineer a couple years ago and he admitted that the C8 has many electrical gremlins. He said this was due to the last minute changes to completely re vamp the electrical system to the new GM global architecture when Mary Barra mandated it at the last minute. He said they have been fighting issues ever since.
Thread Starter
Intermediate
Joined: Nov 2021
Posts: 29
Likes: 3
From: St. George UT
Sorry forgot to mention the apparent fix to the CAN bus problem. The mechanic found a resistance in the CAN bus that was out of spec at a connection some where at the very rear of the car. Spec was 120 ohms and he measured 126. Did drag test and applied dielectric grease. Haven’t had any problems since, knock on wood please. I won’t be surprised if it happens again, especially when the car sits outside on a cold night before track day.
Race Director
Joined: Mar 2001
Posts: 19,918
Likes: 6,712
From: Bonneville Salt Flats
Such are "glitches" with rolling 'puters... sometimes. You may never see it again. I had such some years ago on another new Vette. If it does recur soon, though, I'd check the battery (source of all sorts of issues). Just because it's relatively new means little. Even brand new ones can prove to be bad; don't ask how I know! All the best, in any event. 
Racer
Joined: May 2023
Posts: 303
Likes: 190
Such are "glitches" with rolling 'puters... sometimes. You may never see it again. I had such some years ago on another new Vette. If it does recur soon, though, I'd check the battery (source of all sorts of issues). Just because it's relatively new means little. Even brand new ones can prove to be bad; don't ask how I know! All the best, in any event.
Intermediate
Joined: Sep 2023
Posts: 40
Likes: 16
I have experienced the U0131-00 code twice on track recently. C8 Z51 Race 2. Both times the car got stuck in 5th gear. (I confirmed that the car was still in Automatic mode so, I didn't accidently hit the shift paddles). When I then activated the paddles the transmission shifted ok in manual mode. After pressing the Manual button 2 times it switched back into automatic mode and worked properly. (I could have also held the sift up paddle for 2-3 seconds to put the car back into automatic mode)