I have a 2013 lml duramax. I keep getting a loss comm with gpcm code. I want to check the continuity across the can/bus wires to the ecm to rule out a faulty wire. I have wiring diagrams, but they don't really show much detail on what pins or which ecm connector the gpcm uses. I could figure it out without a pinout diagram, but it would be kind of a pain. Does anyone know where I can find it?
Lml ecm pinout diagram needed
- Thread starter flyinwrenches
- Start date
Hey guys, I need the gpcm pinout as well. I just got around to working on it today, and the pinout diagrams I am finding don't match the gpcm connector on my lml. If anyone has that, I would sure appreciate it. Thanks!
I have a 2013 lml duramax that has the code u0106. Anyways, I am pretty confused right now. I need the gpcm pinout for this truck. The diagram for the older ones don't match this one. I have 11 grounded pins on the connector and no power at all to the connector with the key on. According to my diagram, I should have ign power, 5v ref, and wake up voltage....I have none of that. And to make matters even more weird, after I unplugged the gpcm, it started saying service trailer brake system....how does that have anything to do with the gpcm? I am very confused right now. The only power it is getting is from the main 12v battery feed wire. Any help would be greatly appreciated.
Attachments
Just thought I'd give you this information has a lot of what you might be looking for. Hope it helps....
Go to Chiton website by clicking here - Gale Chiton
The Login ID is 1111720867310
Go to Chiton website by clicking here - Gale Chiton
The Login ID is 1111720867310
Ok, thanks. I wasn't sure if I posted this one in the right category. I seen other similar threads posted in hard parts, so I started a new one in the other category. I wasn't sure though. Thanks for merging it. I am still new to the forum layout.
I went there to check it out, and it sure has a wealth of knowledge there. However, it didn't seem to have the diagrams I needed, unfortunately. I have a Haynes schematic of the comm wires, but it doesn't list pin numbers, nor does it say where the comm wires go. It simply says "to computer data wires".
As for what I have did so far, I used the diagram from 2004lb7 that's posted above (thanks again) and used the diagrams from Haynes that I have and checked the data pins from the ecm plug to the gpcm and could not establish continuity or high resistance. It simply showed open or OL. I removed both fender liners to access the wire harnesses further. I don't see anything bad or frayed. The main harness that runs from ecm to gpcm is very well intact. The factory sleeve and wire loom clips are all in place for the most part. I am at a loss for why I cannot establish a closed circuit. I wanted to see if I could get further information before tearing apart the factory wrapped main harness and inspecting for bad wires... thanks for any help or input!
Nevermind what I said above. I found what I was looking for! It just took a lot of digging. Thank you so much! I hope I can get it figured out now.
