Well I have a 07 lmm 3500hd. It wont crank or start. Also the gear indicator doesn't light up. So I bought this truck wrecked sight unseen 2 years ago. Never do that again. Anyway turns out it needed a frame. Which I bought. Didn't get around to swapping frame until last September. I drove it into my shop and it always started. Even with crap batteries. So I disassembled the truck during the winter. Fast forward to April trucks back together enough to try and start it. Unfortunately no luck. I've tested just about everything , but I'm still missing something. Tried a different ECM,TCM no start. I only get 9.87 volts on the starter relay. Pin 86 I believe. Pin 30 I get 12 volts. The truck will start with a push button connected to the starter if I unhook the TCM and put jumper wires on the Can Bus network. That's the only time my scanner will talk to the truck as well. Sorry for the long post. The thing is driving me crazy. Any ideas would be grateful.