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Discussion Starter · #1 ·
Hi, I'm new here and tried looking for a thread about an electrical issue that I have with my 2007 GMC Sierra 4.8, 147,000 miles, New Body style work truck.
My issue is the following and it happens sporadically, when I'm driving and turn on my turn signal or hit the brakes my radio turns off, the needles on my gauges go hair wire, and some lights (airbag etc) comes on, I'm also hearing kind of like a gargling noise from my radio. Sometimes the truck doesn't want to start. I found out that if I move the cable that comes from the 175 Mega Fuse to the fuse block my truck starts but not all the times. I have done the following; I have replaced the:
1. I replaced the 175 Mega Fuse
2. I replaced the cable that comes from the 175 Mega Fuse to the fuse block
3. I have replaced the Fuse Block (mind you at $200 ouch)
4. I have cleaned all the electrical wires and installed star washers just to make sure the don't come loose
5. I have replaced some grounding wires
6. My battery and Alternator checks out good.
This has been going on for a few years now, took it to the GMC dealer, and two other shops and nobody seems to find what the the issue/problem is. One shop suggested that it was my after market radio so I disconnected the radio for a whole month and it was still doing the issue above.
Any advice or help is greatly appreciated.
 

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Welcome.

I’m not as familiar with the NNBS, but the NBS definitely has a lot of grounding issues. I suspect it’s the same scenario on your NNBS.

I’d try to locate every main ground you can find, and clean them up / replace if needed.

Also sounds pretty obvious the cable you’re referring to has a problem, but you replaced that cable, and still have the problem..?
 

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Discussion Starter · #3 ·
Yes, I bought a brand new one from the dealership and it’s still doing the same thing
 

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My 08 did that, and a lot of others had similar symptoms that turned out to be the BCM. Check that next.
 

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Discussion Starter · #6 ·
Welcome.

I’m not as familiar with the NNBS, but the NBS definitely has a lot of grounding issues. I suspect it’s the same scenario on your NNBS.

I’d try to locate every main ground you can find, and clean them up / replace if needed.

Also sounds pretty obvious the cable you’re referring to has a problem, but you replaced that cable, and still have the problem..?
Yes, I replaced the cable but no luck
 

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Discussion Starter · #7 ·
You said you replaced some grounds, did you replace the main ground cable from the battery-chassis-passenger head? I would intermittently lose power and it got to the point where the truck would just wouldn't start. new main ground was it
I will look for all the ground cables and check them out
 

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Discussion Starter · #8 ·
I will check everything out this weekend and last resort would be replacing the BCM. Thanks for the advice
 

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Discussion Starter · #9 ·
Well, I took and cleaned all the grounds that I found. There are 2 heavy duty ground cables halfway between the cab and the bed on the chassis which I also cleaned. I replaced the new Fuse Block with the old one, I cleaned the connecters from the wiring harness that plugs in the fuse block and also put a thin film of electrical silicone, the fuse block handles were not making the fuse block to have a tight fit so what I did was I screwed large screws on each corner of the fuse block ensuring not to screw any electrical wires. I have driven it for the last 3 days and the symptoms have not returned. Hopefully this took care of the problem (s). Thanks everyone for your advice!
 
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