U0100, and P0700 popping up

[WHAT HAVE I DONE]

when does the ECM come?

[06T200]

It landed at our door Monday. It goes to the dealer Friday morning with the car for install.

[06T200]

Ok got the car in on Friday morning, new ECM installed and was able to pick it up a couple hours later. They cleared the codes and due to the half day holiday schedule the tech was not able to test drive it. So I get about two blocks from the dealer, and just like a ghost in the machine, MIL light's up, and right back into limp mode. Oh that was a fun moment! So dealer is closed by then, so I just suck it up. Once I got time I went over all the schematics for the ECM/TCM, G103, power feeds, grounds, etc. I noticed one connector C101 that I had missed when I was checking the harness a month back, and everyone else may have missed as well, it is down under the coolant tank, just getting to it was a bit of a challenge. It wasn't dirty or corroded, so I cleaned it with q-tips and cleaner, and silicone greased it. It may be going back to the dealer, but since I cleaned that up the U0100,P0700,U0073 are not popping up every few blocks. Who knows at this point.

[06T200]

Update: I think five months of no MIL, no limp mode, no anything is a sure sign C101 was in fact without a doubt the actual CAUSE of these errors. - Maybe make this one a sticky?? I think my last post was not clear since this was such a long drug out problem, but I attest it has been resolved, not by new ECM, not new TCM, - but C101.

[copper]

Where is the C101 ground on a 2010 Aveo LT? I cleaned 2 by the battery and ECU but still getting the P0700 and U0100 codes.

[06T200]

Where is the C101 ground on a 2010 Aveo LT? I cleaned 2 by the battery and ECU but still getting the P0700 and U0100 codes.

On a 2010 I couldn't tell ya. If you can get access to the TIS wiring schematic, it will show the locations of all connectors. This set of codes indicates a faulty connection on the CANBUS between the PCM/ECU and the TCU. Find this circuit, and check ALL connectors along the circuit. One should be dirty/corroded, or a loose/broken wire. I lost access to the TIS library sometime around 2019, so I can't look it up for you. Sorry.

Best of luck, I know this one stumps a lot of techs.

[copper]

On a 2010 I couldn't tell ya. If you can get access to the TIS wiring schematic, it will show the locations of all connectors. This set of codes indicates a faulty connection on the CANBUS between the PCM/ECU and the TCU. Find this circuit, and check ALL connectors along the circuit. One should be dirty/corroded, or a loose/broken wire. I lost access to the TIS library sometime around 2019, so I can't look it up for you. Sorry.

Best of luck, I know this one stumps a lot of techs.

Thanks 06T200, Ill keep looking!