C8 problems
Le Mans Master
Joined: Apr 2013
Posts: 6,671
Likes: 4,144
2020 C8 of the Year Finalist - Unmodified
So we hooked up a battery pack starter to my battery. The dash and lights turned on and the doors opened. The battery voltage was 12.2V but the car would not start at all. Not even try. When we removed the battery pack the voltage dropped in less than 20 seconds to 7.6 and then shut down completely off.
Whatever is happening is draining the battery at some incredible rate. Tow truck driver could not get it out of my building. Its up to Chevy now to figure out what to do because this car is nothing but a paper weight sitting in the basement of my building right now. Maybe send a tech to my place?
IRONY after all that. 2 minutes later ONSTAR sends me a text my battery is critically low. Gee-- thanks for letting me know 5 hours too late.
Whatever is happening is draining the battery at some incredible rate. Tow truck driver could not get it out of my building. Its up to Chevy now to figure out what to do because this car is nothing but a paper weight sitting in the basement of my building right now. Maybe send a tech to my place?
IRONY after all that. 2 minutes later ONSTAR sends me a text my battery is critically low. Gee-- thanks for letting me know 5 hours too late.
Last edited by Sin City; May 18, 2021 at 12:24 AM.
Instructor
Joined: Feb 2017
Posts: 232
Likes: 50
From: Oakland CA
Glad you found the battery and frunk release keep us posted. Im beating there is one small issue once found and fixed you'll be back on the road in style. There is some good information on youtube, and a lot of BS.
Good Luck…
Good Luck…
Burning Brakes
Joined: Sep 2019
Posts: 1,216
Likes: 1,182
Modified C8 of the Year 2021 Winner
Instructor
Joined: Aug 2019
Posts: 248
Likes: 118
From: Virginia
Thanks for this info. I got a check engine light and alert on Sunday for this. Took it in yesterday to the dealer. They performed the self-cleaning process but the light came back on during their road test. Now they are sending this to the engineers to see what's next. Anyone's guess as to what's next.. it's a bummer, but at least that's what warranty is for.
Here is the entire repair procedure including DTC codes;
Fig. 20
The cleaning procedure should be performed three times. If required, perform the solenoid cleaning for each additional DTC that may have set and complete the solenoid cleaning three times. Once completed, it will be necessary to perform the Service Clean Procedure followed by the Transmission Service Fast Learn.
TIP: The cleaning procedure is targeted for mechanical and hydraulic conditions. If circuit diagnostics are required to determine the repair, valve/solenoid cleaning, Service Clean, and the Service Fast Learn will not address the issue.
Cleaning Procedures Based on DTCs Set
Use GDS2 to perform the following cleaning procedures for the DTCs set in the TCM.
If DTCs P194F, P1950, P0747, P0746, P0777, P0776, P2809, P2808, P2724, P2723, P1955, P0797, P0796, P2715, P2714, P2818, P2817, P08C5, P08C4, P27BA, P27B9, P27C2, P27C1, P27CA, P27C9, P27D2, P27D1, P282A, P2829, P1956, P1957, P1958, P1959, and/or P2735 are set:
If DTCs P18A8, P18A9, P2821, P2820, P187D and/or P187E are set:
If DTCs P2855, P2853, P2856, P2854, P0869, P0868, P0867, C2A18 and/or C2A19 are set:
If DTCs: P0844, P0841, P0849, P0846, P0874, P0871, P0879 and/or P0876 are set:
If DTCs: P1946, P1947, P1948, P1949, P194A, P194B, P194C, P194D, P194E, P073F, P074A, P074B, P074C, P074D, P074E, P074F, P07D8 and/or P073E are set:
Service Procedures
After recording and clearing the DTCs, and with the transmission at operating temperature, use GDS2 to perform the Transmission Service Cleaning Procedures. (Fig. 21)
Fig. 21
Select the transmission cleaning services that correspond with the DTCs set. (Fig. 22) Not all cleaning procedures listed need to be performed.
For more details about each cleaning procedure, refer to SI document #5501008 – K71 Transmission Control Module: Scan Tool Information.
Fig. 22
Perform the DTC solenoid cleaning procedure three times for each DTC set. Once the cleaning procedure has been completed three times, select the Configurations/Reset Functions in order to perform the Transmission Service Fast Learn procedure as needed.
Be sure to test drive the vehicle after performing the cleaning procedures to verify that the DTCs do not reset. If the DTCs reset, replace the Control Valve Solenoid (or Main Control Valve, MCV).
For additional information, refer to Bulletin #21-NA- 033.
– Thanks to Dave Rainey
Updated March 1,2021
Multiple Transmission DTCs Set
February 26, 2021Some 2020-2021 Corvette models may have multiple DTCs set in the Transmission Control Module (TCM). The DTCs may be caused by an internal transmission solenoid or switch sticking due to debris in the DCT TR-9080 transmission (RPO M1L). (Fig. 20) Based on the DTCs that are set, GDS2 should be used to perform the appropriate solenoid cleaning procedure.Fig. 20The cleaning procedure should be performed three times. If required, perform the solenoid cleaning for each additional DTC that may have set and complete the solenoid cleaning three times. Once completed, it will be necessary to perform the Service Clean Procedure followed by the Transmission Service Fast Learn.
TIP: The cleaning procedure is targeted for mechanical and hydraulic conditions. If circuit diagnostics are required to determine the repair, valve/solenoid cleaning, Service Clean, and the Service Fast Learn will not address the issue.
Cleaning Procedures Based on DTCs Set
Use GDS2 to perform the following cleaning procedures for the DTCs set in the TCM.
If DTCs P194F, P1950, P0747, P0746, P0777, P0776, P2809, P2808, P2724, P2723, P1955, P0797, P0796, P2715, P2714, P2818, P2817, P08C5, P08C4, P27BA, P27B9, P27C2, P27C1, P27CA, P27C9, P27D2, P27D1, P282A, P2829, P1956, P1957, P1958, P1959, and/or P2735 are set:
- Perform the system cleaning procedure based on the DTC that set.
- Next, perform the Service Clean Procedure and then the Service Fast Learn.
- If DTCs return, replace the valve body as necessary.
If DTCs P18A8, P18A9, P2821, P2820, P187D and/or P187E are set:
- Perform the system cleaning clean procedure based on the DTC that set.
- Next, perform the Service Clean Procedure and then the Service Fast Learn.
- If DTCs return, transmission replacement may be necessary. Contact the GM Technical Assistance Center (TAC) for more information prior to ordering a transmission.
If DTCs P2855, P2853, P2856, P2854, P0869, P0868, P0867, C2A18 and/or C2A19 are set:
- Perform the system cleaning clean procedure based on the DTC that set.
- Next, perform the Service Clean Procedure and then the Service Fast Learn.
- If DTCs return, replace the valve body as necessary, except if DTC P0867 (Transmission Fluid Pressure Performance) is set. No system pressure is either a serious mechanical issue or extremely low fluid level.
If DTCs: P0844, P0841, P0849, P0846, P0874, P0871, P0879 and/or P0876 are set:
- Perform the system cleaning clean procedure based on the DTC that set.
- Next, perform the Service Clean Procedure and then Service Fast Learn.
- If no other pressure DTCs are present, proceed to circuit diagnostics.
If DTCs: P1946, P1947, P1948, P1949, P194A, P194B, P194C, P194D, P194E, P073F, P074A, P074B, P074C, P074D, P074E, P074F, P07D8 and/or P073E are set:
- Perform system cleaning cleaning IF accompanied with low/high system pressure codes; otherwise, perform the Service Fast Learn.
- Failure of the Service Fast Learn would indicate a mechanical hardware condition.
Service Procedures
After recording and clearing the DTCs, and with the transmission at operating temperature, use GDS2 to perform the Transmission Service Cleaning Procedures. (Fig. 21)
Fig. 21Select the transmission cleaning services that correspond with the DTCs set. (Fig. 22) Not all cleaning procedures listed need to be performed.
For more details about each cleaning procedure, refer to SI document #5501008 – K71 Transmission Control Module: Scan Tool Information.
Fig. 22Perform the DTC solenoid cleaning procedure three times for each DTC set. Once the cleaning procedure has been completed three times, select the Configurations/Reset Functions in order to perform the Transmission Service Fast Learn procedure as needed.
Be sure to test drive the vehicle after performing the cleaning procedures to verify that the DTCs do not reset. If the DTCs reset, replace the Control Valve Solenoid (or Main Control Valve, MCV).
For additional information, refer to Bulletin #21-NA- 033.
– Thanks to Dave Rainey
Updated March 1,2021
Le Mans Master
Joined: Apr 2013
Posts: 6,671
Likes: 4,144
2020 C8 of the Year Finalist - Unmodified
SOoooooooooooooooooooo... if your battery dies:
1) use the mechanical key to open the door
2) find the little wire loop about 3 inches to the left of the steering column where it touches the firewall. Full down TWICE to open the front hood. Its not marked so you have to have a bit of leap of faith. Mine was not even visible. I had to fish around for it and pull it down.
3) remove the two side plastic panels on the left and right side that hold down the main panel over the battery
4) carefully pull that large center panel up one clip at a time
5) You need to get the voltage or current higher than a normal battery jumper. We used TWO jumpers at the same time. This gave us the necessary current to make the starter work
When the car starts you're going to see all kinds of warnings pop up on the dash. Ignore them. Some will go away. I had warning about windows being down, the top not being secure, the parking brake failing. When it was all over all I was left with is the check engine light on.
I drove it to the dealer this morning after it started. Ran normally. Waiting to see what they say. What a PITA.
1) use the mechanical key to open the door
2) find the little wire loop about 3 inches to the left of the steering column where it touches the firewall. Full down TWICE to open the front hood. Its not marked so you have to have a bit of leap of faith. Mine was not even visible. I had to fish around for it and pull it down.
3) remove the two side plastic panels on the left and right side that hold down the main panel over the battery
4) carefully pull that large center panel up one clip at a time
5) You need to get the voltage or current higher than a normal battery jumper. We used TWO jumpers at the same time. This gave us the necessary current to make the starter work
When the car starts you're going to see all kinds of warnings pop up on the dash. Ignore them. Some will go away. I had warning about windows being down, the top not being secure, the parking brake failing. When it was all over all I was left with is the check engine light on.
I drove it to the dealer this morning after it started. Ran normally. Waiting to see what they say. What a PITA.
Last edited by Sin City; May 18, 2021 at 04:17 PM.
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Instructor
Joined: Nov 2020
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Last edited by vette2021HTC; May 18, 2021 at 05:44 PM.
Instructor
Joined: Sep 2005
Posts: 244
Likes: 91
From: Batavia ILL
As stated in post it was produced 2/20.Always garaged. 4000 miles.Car split time between IL and FL. Was happening before transporting to FL. It got significantly worse while parked in garage in Florida. Anyway it looks like an easy warranty issue. Sold car yesterday so new owner will deal with it.
Instructor
Joined: Aug 2019
Posts: 248
Likes: 118
From: Virginia
Thanks for this info. I got a check engine light and alert on Sunday for this. Took it in yesterday to the dealer. They performed the self-cleaning process but the light came back on during their road test. Now they are sending this to the engineers to see what's next. Anyone's guess as to what's next.. it's a bummer, but at least that's what warranty is for.
So, definitely an issue that they seem to be getting a handle on.
Melting Slicks
Joined: Apr 2021
Posts: 2,597
Likes: 2,653
From: Texas
UGH, this is exactly what I was worried about with 3LT. I really really really hope this is an isolated case. If more of these start popping up my decision to go back down to 2LT will be far easier to make, even if it means I can't get the exact color combo I want. Also wondering if it's more common in high humidity locations than low humidity ones.
Would it be SO hard for these manufacturers (since chevy isn't the only one with dash pulling issues on leather dashes) to use a quality adhesive that wont come off the minute the leather starts to expand/contract?
Would it be SO hard for these manufacturers (since chevy isn't the only one with dash pulling issues on leather dashes) to use a quality adhesive that wont come off the minute the leather starts to expand/contract?
Melting Slicks
Joined: Oct 2004
Posts: 2,187
Likes: 173
From: Nevada
Hi guys I am thinking about getting a 2021 or 2022 C8, so are the problems minor or are some major ones? I read couple pages but those were on the first model year so maybe later years don't appply.
Would those problems stop you from ordering C8 again?
Would those problems stop you from ordering C8 again?
Le Mans Master
Joined: Sep 2017
Posts: 5,767
Likes: 2,967
From: Rural NW Georgia. GO DAWGS!
2024 C8 of the Year Finalist - Unmodified
SOoooooooooooooooooooo... if your battery dies:
1) use the mechanical key to open the door
2) find the little wire loop about 3 inches to the left of the steering column where it touches the firewall. Full down TWICE to open the front hood. Its not marked so you have to have a bit of leap of faith. Mine was not even visible. I had to fish around for it and pull it down.
3) remove the two side plastic panels on the left and right side that hold down the main panel over the battery
4) carefully pull that large center panel up one clip at a time
5) You need to get the voltage or current higher than a normal battery jumper. We used TWO jumpers at the same time. This gave us the necessary current to make the starter work
1) use the mechanical key to open the door
2) find the little wire loop about 3 inches to the left of the steering column where it touches the firewall. Full down TWICE to open the front hood. Its not marked so you have to have a bit of leap of faith. Mine was not even visible. I had to fish around for it and pull it down.
3) remove the two side plastic panels on the left and right side that hold down the main panel over the battery
4) carefully pull that large center panel up one clip at a time
5) You need to get the voltage or current higher than a normal battery jumper. We used TWO jumpers at the same time. This gave us the necessary current to make the starter work
Melting Slicks
Joined: Oct 2004
Posts: 2,187
Likes: 173
From: Nevada
Someone chime in on this, I think if you let car sit 7 to 14 days I think it's no problem for the battery. After that put a battery tender in. (assuming car and battery got no problems)
It will start after 28 days of sitting but after it's almost out of juice and might not start couple days after that. If you wait until around 28 days and put the battery tender on, the battery might not last as long as say after 7 to 14 days. But correct me if I am wrong on this.
It will start after 28 days of sitting but after it's almost out of juice and might not start couple days after that. If you wait until around 28 days and put the battery tender on, the battery might not last as long as say after 7 to 14 days. But correct me if I am wrong on this.
Le Mans Master
Joined: Sep 2017
Posts: 5,767
Likes: 2,967
From: Rural NW Georgia. GO DAWGS!
2024 C8 of the Year Finalist - Unmodified
Someone chime in on this, I think if you let car sit 7 to 14 days I think it's no problem for the battery. After that put a battery tender in. (assuming car and battery got no problems)
It will start after 28 days of sitting but after it's almost out of juice and might not start couple days after that. If you wait until around 28 days and put the battery tender on, the battery might not last as long as say after 7 to 14 days. But correct me if I am wrong on this.
It will start after 28 days of sitting but after it's almost out of juice and might not start couple days after that. If you wait until around 28 days and put the battery tender on, the battery might not last as long as say after 7 to 14 days. But correct me if I am wrong on this.
As with other cars with hard to get to batteries someone will devise a way to run wires from the battery to a point, and I would imagine it might be in an inconspicuous place outside the front end, where you can hook up a battery tender/maintainer without opening the frunk.
Last edited by Fast Dawg; May 20, 2021 at 04:51 AM.
Instructor
Joined: Feb 2017
Posts: 232
Likes: 50
From: Oakland CA
OMG its EASY to get to the battery, those who think its to hard should probably stay with hot wheels. Get a battery tender pigtail and extention, DONE.
Last edited by Jimp94605; May 20, 2021 at 07:38 AM.
Racer
Joined: Jan 2021
Posts: 431
Likes: 131
From: Plano, Texas
it plugs into the frunk and no trouble involved
Le Mans Master
Joined: Sep 2017
Posts: 5,767
Likes: 2,967
From: Rural NW Georgia. GO DAWGS!
2024 C8 of the Year Finalist - Unmodified
Would either of you care to elaborate?
Last edited by Fast Dawg; May 20, 2021 at 08:09 AM.