TCM, Dashboard, and OBD2 Power Issue

[MAXX IT OUT]

I have had a issue for 4-5 years where randomly the dash would lose power for a second while driving and it would instantly come back on. Now it doing it very multible times in a 10 miles drive down the interstate, along with sometimes killing the CTS2 and generally the truck kind of shutters, once it felt like the truck was kicked in the balls. I am sometimes getting a P0880, TCM power input signal code. Is there a common fuse/wire bus that feeds all the other control modules? I am worried that its going to bind up or miss shift destroying the transmission.

 

[Mikey52]

What year truck?

It could be the under hood fuse block. They have been known to house rodents or get bad corrosion..

 

[MAXX IT OUT]

2001, opened up the fuse box and nothing is jumping out.

 

[2004LB7]

What about the grounds on the A piller and behind the radio? Or the infamous ground under the drivers door on the frame?

 

[Ron Nielson]

Maybe something in the attachments for you

 

[MAXX IT OUT]

What about the grounds on the A piller and behind the radio? Or the infamous ground under the drivers door on the frame?

I am not seeing any grounds in either location, I just cleaned the ground on the frame and checked the engine grounds.

 

[gmduramax]

Could be the connection at the OBD II for the edge or the edge itself.

 

[2004LB7]

I am not seeing any grounds in either location, I just cleaned the ground on the frame and checked the engine grounds.

I think ground 203 is for the DIC

 

[MAXX IT OUT]

It only goes dead for about 3 seconds, then instantly restarts, so it it seems like a relay or fuse loses power the. It comes right back.

 

[2004LB7]

What about the ignition? Doesn't power run through there?

 

[Ron Nielson]

Lots of grounds on these trucks

 

[Chevy1925]

Cali or federal emission truck?

 

[MAXX IT OUT]

Ron, thanks for the list, hope that the 2001 harness is more or less the same.
James, it a federal truck.

 

[Chevy1925]

For shits and giggles, try disconnecting the glow plug control module. Sometimes the relay sticks in them and causes a back feed that can screw with the trucks. I’m not hopeful but something to check

 

[MAXX IT OUT]

Life and work has been super busy, but I believe I might have found the problem. I just when ahead and swapped out the chassis side wiring harness with one I had in the parts pile. There was a pair of nicks in wires going from the fuse block to the TCM, as well as some questionable splices at the nsbu switch. When putting the new harness in, I found that one of my battery cables running to the starter was laying on the transmission and had rubbed threw the insulation. My batterys are mounted on the frame rail under the drivers side rear door and the cable P clamps broke, so my current guess is that it would short on the transmission and cause the TCM to shut off. I haven't gotten the truck driving yet, since I found a big boost leak where the inner fender rubbed threw a intercooler pipe and haven't gotten that welded back up yet. Hopefully this is the problem.