Try to make this short...2001 Peterbilt 379 Cat C12 starter stays engaged after engine starts and shut switch off and starter stays in still engaged trying to crank engine over....This is what I have replaced: Wiring harness from firewall to ECM and starter Replaced starter Replaced starter relay Replaced starter interrupter relay in dash Replaced batteries Replaced key switch Pull the relay plug on firewall and will stop cranking Try tracing wire that excites relay from key switch and gets down in jungle of wires and loose, I think it is #19 wire Wiring diagram would be big help but can't find one.... Any help would be greatly appreciated, this is my own truck and I think it almost has me whipped.....THANKS
Remove the left kick panel and one in front of clutch. Check back of fuse/relay box for chard wiring. Just a thought-Pete had trouble in that area in those years.
That's a start thank you will post findings...