Hey guys, I need some help troubleshooting my truck. I’m gone for weeks at a time for work so when I leave I disconnect my passenger side battery, leave the drivers side on because it’s shot anyway. When I came home from work I connected the passenger side battery and my fass started running like the key was on. I went in the truck and the gauge cluster was powered on as well. When I put the key in and turned the Ignition on, the wait to start light didn’t come on, tried to start it and crank no start. I turned the key off and the fass kept running and the cluster stayed powered up. Only way I can get the truck to start is if I disconnect the batteries, and put only the passenger side one on, then when I turn the key on the wait to start light comes on, truck starts, but runs rough and oil pressure gauge reads no oil pressure. I have a quadzilla wired into the drivers side battery, truck is a 2000. When the key is out of the truck with the ignition off the cluster is always powered on and fass stays running. Codes that came up when it happened are P1689, P0238, P0236, P0382, P0380

Edited May 24, 2024May 24 by White wondee

First thing. Replace both batteries with new batteries. Then might be a good idea to do the W-T ground wire mod. Also have your alternator tested for AC noise. Weak batteries can cause all kinds of issues.