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K. Wiggins
K. Wiggins, ASE Certified Technician
Category: GMC
Satisfied Customers: 2915
Experience:  ASE Certified Technician, Associates Degree in Automotive Technology, 15+ years in the trade
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I have a 2008 sierra I've had electrical issues for the last

Customer Question

I have a 2008 sierra I've had electrical issues for the last 4 years. My issues normally start were the radio resets after it losses power for a second, that's the first sign of trouble, then I notice the volt meter is charging high, then if I have the cruise on the cruise will kick off if I use a turn signal or the head light dimmer switch. I've replaced the battery, positive cable, and the radio. Two days ago it happened again, noticed the volt meter high shut the truck off and everything went completely dead the door locks would not work no power to anything. I went to my meeting and on break times I'd check it by hitting the unlock button after about the third try it unlocked and the lights flashed like normal, it started and I made it home, but the volts were high again and the cruise had its issues, shut it off at home and it went dead again but just for a few seconds the dome lights came back on went to start this morning completely dead again no power to anything. Any ideas
JA: Is the power loss consistent, or does it fluctuate?
Customer: It progresses starting with the radio and then different parts like the cruise. Every time this has happened it does it for like two weeks then stops for months. This is the worse it's ever been
JA: Are you fixing your Sierra yourself? What have you tried so far?
Customer: I have a mechanic doing it, he is not with a gm dealership, but he has scanned it and nothing abnormal has shown up, the only thing we can come up with is it has a issue with power getting to the main fuse control box
JA: Anything else you want the mechanic to know before I connect you?
Customer: not that I can think of
Submitted: 6 months ago.
Category: GMC
Expert:  K. Wiggins replied 6 months ago.

Hello, he needs to perfrom a voltage drop test on the wires going from the battery to starter as well as to the fuse box. ALso check the connections at the body control module as well as the grounds at the battery, and body to frame. I'll post the wiring diagrams below for his reference. Most all of the issues you are having are items that operate from the body ocntrol module

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