92 gmc sierra 4.3.When i turn on anything electrical my truck shuts down. Reading 6 volts on ground wires. More so with the lights. Just bought truck don't know much about it.

Asked by Aug 04, 2014 at 01:57 PM about the 1992 GMC Sierra 1500 K1500 4WD Standard Cab LB

Question type: Maintenance & Repair

12 Answers

34,635

Is your alternator putting out 6 volts? That's a problem.

No. Altinator is putting out 14 volts.

34,635

Well that's good news. Have you tried cleaning the ground straps yet? Your alternator is making good power but it seems like its having a hard time getting back.

Would that cause me to have 6 volts going through my grounds. Correct me if I'm wrong but there shouldn't b any voltage through my grounds right

34,635

Right! Under what conditions did you get this truck? Was it a known....... mystery?

Ya. It was wrecked in the front I went over the wiring across the rad support. Didn't find anything. Could a bad bulb do this. Also when I unhook my headlights it also shuts the truck down and won't let it start. It does seem to b getting worse. I don't know if its from me messing with it or just from driving. I can power stuff directly from battery with no issues. Even when I unplug my headlight switch it shuts off. I'm at a loss.

34,635

A bad bulb shouldn't do that. Check for pinched wires. It's going to be something small and stupid. It's just a matter of finding it. Try moving he wiring hardness around and see if you can find a short.

I've jiggled and wiggled every wire under the hood and 90% under dash. Its hard to know cause it will run fine for a little and start fluctuating the idle I'm gonna start opening all the wire harness and start looking. I did some more testing and I have 6 volts on driver side light ground and not the passenger side. I'm gonna pull apart the harness and start looking in between the lights. Looking at it without opening it it all looks good. No melted sheathing. Just a spot where it looks like someone had opened the harness and retaped it not sure but that is where I'll start. Thanks for all the info. I'm a pretty good mechanic but when it comes to wiring I'm lost lol. I'll let u know what I find. Might b a while. I know it takes lots of time to trace wiring. What's ur thought about it shutting down when I unplug my head lights. U think still short in wire

Or something wired wrong

34,635

I've been thinking. ( Look out) Your getting 6 volts. What part of what runs on 6 volts???? And when it fails it runs backwards???? Could it be something like a fan???? Hummmmmmm

I got it fixed last night. They had the battery grounded wrong. It wasn't properly grounded to the frame. They had the ground running through the lights before it touched the frame. I just had to run a new wire from the battery to the frame and fixed my problem. They had it grounded to the motor and the other ground wire ran to the rad support and had the lights grounded to that wire. Thanks a bunch for ur help. Hopefully I can return the favor some day. Greatly appreciated

34,635

Well I'm glad! :-) Sometimes it's the simplest things. I'm still at a loss as to the 6 volt coming through the negative ground wire.

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