I'm new here so hello. I've tried searching here and Google and anywhere else on internet. Ive found many people with similar problems and their solutions but can't seem to find anybody with the same combination of issues as I have.
2003 gmc 2500hd 8.1 w/ Allison. Just bought this truck a month ago. It's got a shitty 3 month warranty on engine and trans. Dealer is 50 miles away, not trying to tow it if I don't have to but this might be out of my league.
I started it up one day and it's telling me to service brake system. Abs light is on, brake light is on. Its stuck in 3rd. It shifts hard into reverse and drive and there is no gear indicator light underneath PRD321. The speedometer and trans temp gauges aren't working, and it won't display the instant fuel efficiency.
This happened once, drove it two miles and it all of a sudden went away and drove like normal. Two days later it happened again and its been this way for a week now.
Current codes I'm getting are p0802, p1571, c0035, c0055, u1000
Codes stored in history are c0040,u1009, u1003,u1007, u1255, c0327, b0790, u1301, p0500
So far I've changed the neutral safety switch, vehicle speed sensor, and ignition switch. I attempted to change the wheel speed sensors but I can't get the damn brakes off, the whole assembly is so damn rusty it's ridiculous. The brake fluid level is good.
I don't know where to start, or where to go from here anyway since I've already replaced a few things. I'm guessing I have a bad ground somewhere or maybe my tcm is bad. Any advice would be greatly appreciated.
