Howdy. I have an 09 cutaway 3500 with a Duramax in it, and a few months ago my instrument display panel started showing lower then normal voltage, but my cts is displaying normal system voltage as well as a meter (13.5-14.5). As time went on, I started having problems with my cruise control, then eventually my signal lights and cab light/dimmer switch.. now it displays 9v or below (the gauge is resting on minimum), cruise doesn't work at all, no signal lights etc. my system voltage is still normal at both batteries, grounds are good at both batteries, me and a friend spent a few hrs looking into it but we can't figure it out. We've checked all the basics including pulling the instrument panel and we still have 14v ( and everywhere else in the truck, both batteries, alternator, fuse block, everywhere as verified by a meter) at the back of that. I'm suspecting a corroded to **** engine bay fuse box since it doesn't look the best, or maybe an issue with the bcm... Anyone ever ran into this that could help me find the smoking gun? Thanks!

 

1st thing I would do (besides investigating the fuse box) is remove/clean/replace all grounds. And consider new battery cables as well