Fuel Gage Issue

[Biggie C]

I recently installed a new sending unit in my 1971 LeMans. I also installed a new headlamp switch. Now when I turn on my headlights the fuel gauge moves towards empty. Turn off headlights and it moves towards full. I also noticed it moves when the blinkers are turned on. One onther bit of info is I installed a ACP halogen headlamp kit with LED halos. I have been told it is a grounding issue, but I can't seen to track it down? Any help in troubleshooting will be appreciated.

 

[melsg5]

Did you replace the sender and the headlight switch at the same time?
Why did you replace the headlight switch?
Are you using a relay for the new headlights or is all the current going through the headlight switch?
Did you try putting the stock headlights back in?

 

[Biggie C]

No relay for new switch. Did not try old headlights, but even if I just pull switch out one click for parking lights, it still happens. Switch was real loose and upon inspection saw that it was cracked. sending unit was replaced (last week) after headlights (6 mon ago) and switch (4 mon ago) but noticed fuel gage movement after I installed it (sending unit) but thinking back, fuel gauge di move alot and I did not really trust it, that's why when it stopped moving all together i replaced sending unit. Cleaned all grounds that I could find and all fuses last night. Looked at front end electrical dwg and see that headlights have a ground (on body?) I could not locate it any idea where this is? Engine ground cable to battery is clean and new and has the cable to the front fender as well and that is clean,

 

[cammerjeff]

I would think it has to do with a ground to the headlights not good, and when your lights are on they are finding a ground somehow thru the fuel sender. I would check all the grounds on the front headlights and turn signals

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[melsg5]

if you look at the wiring from the headlights themselves I believe you will find the ground is on the radiator support.

 

[Biggie C]

Thanks for the guidance. I have been tracing the wires, but they appear to be in the wiring loom without any offshoots to the core support. If anyone has a specific location (driver or passenger side?) I would appreciate it.

 

[Biggie C]

sep 22 update

Still no luck. I have replaced headlamp switch. Ran a new ground into headlamp circuit. Checked / cleaned the ground on the sending unit. next will try going back to original headlamps.