2006 c3500HD with no accessory power...

rgeorge101 · March 15, 2012

We recently bought a 2006 c3500HD ext cab, 6.0L gasser, cab and chassis with a dump body. We are experiencing an odd problem with it... when we bought it, it had been pretty much dormant for a few years, it only has 26000 miles on it now. Right out of the gate it started cycling through languages on the odometer with no user input, i thought, no biggie, the reset button must be sticking. Then the fuel gage started to work incorrectly and the rear aux tank did not pump fuel to the front one. Then there was an issue with the battery draining. We were ready to replace the battery, but before we got the chance all the accessory power stopped working. We have no dome light, the headlights only come on when the truck is running, and the dash lights completely don't work. The radio has now quit. When I turn the key to the first position, I get nothing. the gauges click sometimes briefly when it turn the key but other than that, nothing. the truck 'broke down' the other day because the front tank was empty (we did not know our fuel tank was close to empty at our shop and the fuel stopped before it was full)

The truck runs and drives fine, just the electrical stuff is not working correctly. I checked all the fuses under the hood and in the fuse panel in the dash on the left side. We also got a new rear fuel pump installed, a new headlight switch installed, and a new 800 CCA battery installed. I am stumped as far as where to look next. If you can provide any insight, I would greatly appreciate it. Thanks!

gmtech4 · March 16, 2012

sounds like a BCM being rather cranky....MAY need a reprogram

stop throwing money and parts at it and take it to a GM garage for diagnoses,good luck

rgeorge101 · March 16, 2012

Thanks for the info... I plan to bring it to the dealership soon, they are cranky when I want to bring it there because its a dump body and they don't sell them anymore... they claim the service bays aren't big enough.

I love the GM trucks that we have, while my brother likes the Fords (puke) and of course he was driving it when this happened.