U0101

[Skyhigh4by]

Had cab off to do head gaskets, put cab back on and got truck running again. Everything was working fine after a few short test drives besides a fuel pressure code (P0089). It then sat for a few weeks and now I insure it and am ready to put it back on the road then suddenly out of no where I get the whole stuck in 3rd, no gear indicator, no back up lights, no speedo, no trans temp, ABS/service brake system, PLUS my glow plugs start acting up at the same time.

I tried a new NSBU and VSS with no luck. I also confirmed continuity from VSS to TCM and also confirmed 12v power to TCM. Also checked all fuses, confirmed that the VSS reluctor is firmly where its supposed to be. Grounds and batteries are good. Gone over ECM and TCM connectors multiple times thinking maybe there was a bad connection but doesn't seem to change anything.

The glow plug codes and TCM code seemed to happen at the same time like they are somehow related..

Got it scanned and the codes are as follows...
U0101
P0089
P0673
P0675
P0677

 

[Mike L.]

You have wiring problems.

 

[Skyhigh4by]

As in a bare and/or pinched wire or a plug somewhere not making full contact?

I have taken the TCM and ECM plugs off to look at the pins and from what I can tell they look fine. Any particular spot I should be looking first? Any way I could somehow narrow it down?

 

[ironmax]

Have you checked your ground connections?

 

[onebaddmaxxx]

I would check power and grounds at the tcm. there is a power wire iv seen break quite a few times usually within 12" of the connector.

 

[Skyhigh4by]

I checked/cleaned the ground connections at the front driver side cab mount, under drivers door, and from engine to cab. Besides those three what other grounds are there? Can anyone telle which pins in the TCM plugs are supposed to be power and ground?

 

[Skyhigh4by]

On the grey plug at the TCM I have confirmed that the grounds in pins 1&5 have continuity to the engine and to the battery negative. I have also confirmed that the Orange wire in pin 3 has constant 12.3v with the key off. The pink wire in pin 4 has 11.8v with the key on. The schematic I have shows that there should also be a pink wire in pin 2 that looks to be the same circuit as the pink in pin 4. There is nothing in pin 2 on my truck..

I cant find anything visibly wrong with any of the wires going from the grey TCM connector back to the fuse block.

 

[Skyhigh4by]

while parked not running but with the ignition on the rear driver side door is making a bunch of clicking noises like the window motor is trying to go up or down and I can't make it go up or down with the front or rear button. Also just moved it and the turbo vanes started cycling open/closed really fast (about every second)

 

[Mike L.]

I read somewhere that there are 2 identical connectors that can be crossed in the harness.

 

[Skyhigh4by]

I read somewhere that there are 2 identical connectors that can be crossed in the harness.

Could be but it wouldnt make sense that it was all working fine and then suddenly all this just started happening without taking anything apart.

It did happen right around the same time I put all new front bulbs in and installed the inner fenders. I cant find any signs in the are though.

I read about the TCM possibly grounding out?? Is there some way I can test it? i read to check for continuity between pin 9&69 or something like that but my TCM has 2 plugs and they both go up to 30 so I dont know where pin 69 comes from..

Im at a stand still. Dont know what to do next

 

[Skyhigh4by]

When I disconnect/reconnect the batteries there is alot of arcing. Something is pulling a draw pretty hard somewhere but I cant figure out where. Should there be any draw at all in this system with nothing on and all doors closed? Is there a procedure to find an electrical draw? Load tested both batteries again and they both check out. Going to pull out entire trans harness and go through it with a fine tooth comb.

Also just observed that the auto door locks aren't working anymore.

I found one loose ground on the driver side of the engine block. I was really hopeful the ring terminal looked like it had been arcing a bit. I cleaned it up and tightened it down but that didnt solve anything.

Spoke with local gm dealer and that wasn't any help. Just want me to bring it in but at $110/hr it's not exactly feasible for me to do that.

 

[Skyhigh4by]

Starting to feel like an annoyance being the only one posting but I'm pulling my hair out here. Anyways.. Is there any chance all of this could be due to a faulty ignition switch?

 

[05LLYDMAX]

Not saying its the same for you but I had a U0101 code and occasional limp P0700 Mike was nice enough to give me his 2001 TCM and it all went away.

 

[Skyhigh4by]

Im at that point now. I tore the entire harness out and went through it. I also tried an ignition switch.

Best price I have found for a new TCM here is just shy of $1000 and with no guarantee that it will fix the problem and can't be returned Im a little bit gun shy.

Can a TCM from any 5 spd Alli work? Would it need to be reprogrammed?