Fuel gauge dies when I turn on my headlights

[F0Rabbit]

Was able to get my 85 1010 running again but noticed a new issue. If I turn on my headlights the fuel gauge drops. Anyone had this problem before?

 

[cucvrus]

I would guess a grounding issue with the cluster. look at the grounds up under the dash above the E brake pedal. Also look at all the grounding connections on the rear and under the hood. But it seems the ground is being starved when the head lamps are on. Does it do the same thing with the park lights? Merry Christmas.

 

[porkysplace]

The thing with electrical problems is there is no one answer fix , the problem needs to be diagnosed.
Start by reading the headlight circuit thread;
[h=1]CUCV Headlight Circuit Explained[/h]This is found in the CUCV helpful threads stickie;
[h=1]CUCV Helpful Threads[/h]

 

[bigmike]

Was able to get my 85 1010 running again but noticed a new issue. If I turn on my headlights the fuel gauge drops. Anyone had this problem before?

I have the exact same issue with my M1008...don't drive at night...problem fixed...at least that worked for me.

 

[MarcusOReallyus]

Rick is on the right track. When electrical gets weird, check the grounds. That 6 prong up on the parking brake is the first place to look.

 

[F0Rabbit]

Merry day-after Christmas, Ill take a look at the grounds once Im back in town. And no I dont think it does it with the park lights, only when I pull the headlights on.

 

[MarcusOReallyus]

Yeah, sounds like a ground issue.