2008 GMC Sierra, gremlins in the electrical

[Matt Yetter]

Hello, this is my first post on here I hope it is clear and in the right place

I have a 2008 GMC Sierra 4 x 4 quad cab 4.8L

I was driving and all electrical began to go haywire, lights flashing, doors locking unlocking, engine die, restart, was crazy. finally completely died and no power, no dome lights or dash, the only power i could find was a dim light on my phone charger in cig lighter. I looked it up on google and it appeared that there could be a bad ground cable and that makes sense so I fiddled with it and got it running again. Got home it wouldn't start after that. I fixed the Neg battery cable and now it starts and charges getting full voltage and good voltage to ground. now the drivers side door locks, and windows dont work, there is no dash lights the left turn signal blinks like a burnt out bulb, the 4 x 4 doesnt work either. This seems like I need to reset some thing but I am at a loss I hope you can help me out.

[Swimmer8366]

Checked all your grounds? Did you by any chance flip your fuse block upside down and check under belly of it for damage?

 

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[Matt Yetter]

I think i checked all grounds:) with power off and probe on pos battery, i tested at neg post, neg clamp and all the way out to engine, had good readings. I did look at my mega fuse but i didnt pull it and look on the back for damage.

[Jsdirt]

Holy crapper - nice elk ya got there in your avatar.

 

I'd do a visual inspection of all your battery connections, and anything else that might be wrong. If one cable was bad, chances are there's another that's bad as well. Look everything over good before you start digging into the thing.

[Coby7]

Check the contacts on the B+ fusible link for corrosion.

[Matt Yetter]

LOL thanks for the compliment on the elk. Archery hunting is a passion.

 

Thanks for the advice I will check the fusible link for corrosion and other cables.

 

It seems that after my electrical system was possessed and shut down, I am holding off on the holy water, just to be safe. But is seems like to many failures to be isolated, I wonder if I need to reset something.

[Jsdirt]

Yeah, might be worth a shot clearing the memory, or disconnecting the battery for some time and reconnecting. Friggin electronics for ya - never know what they'll respond to.

 

Since you guys are in that arctic blast, I'd load test the battery first thing - could have a dead cell, or could just be getting weak. If it's over 6 years old, might be worth replacing it.

[Matt Yetter]

Well I have replaced the - bat cable, added another ground strap from body to motor, cleaned the mega fuse and checked the back for anything unusual. I got a code reader and there were a bunch of codes about neg ground. I give up, I am going to have to detonate this truck.....

[Jsdirt]

How's that battery? You'd be surprised the problems a borderline weak battery (or alternator) will cause in these things.

 

If that all checks out, I'd double check for for some wire that didn't get hooked back up, or a corroded or broken wire somewhere.

 

Hope you find something! Merry Christmas.

[Matt Yetter]

Well I just went through a bunch of crap. 849.00 and now my back door lock actuators need replaced, so the local dealer charged me 104. to run a diagnostic on it, then said it had low voltage on neg and pos cables, so they replaced them they are 98. and 95. buck each. then the additional charges for labor diagnosing and replacing a relay in fuse box... I really feel ripped off.... and for 400 and some change they will replace the rear door lock actuators.... Oh and I scheduled a full day for them to put it on the diagnostic machine, and they were to busy, so it was there for 3 days waiting for someone to work on it... Sorry i am venting a little....

[Jsdirt]

I think GM has their hands full with warranty claims, and can't handle any additional work. Just my take on it. Dealers are a warranty-only proposition, unless you've got deep pockets. Plenty of small garages out there that probably could've fixed the truck front to rear for less than half of what a dealer will charge.

 

Sorry to hear that. Par for the course today, unfortunately. They sure don't build 'em like they used to .. and to top it all off, they're all loaded with electronics designed solely to keep the gravy train flowing into Detroit, it seems.