Weird electrical
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5th Wheeling
Joined: Sep 2018
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From: San Diego
Weird electrical
I was bleeding my brakes today and noticed when holding brake pedal down my gas gauge went 1/4 ways past the full mark and dropped back down after releasing the pedal? Anyone else seen this?
Post Fiend
Joined: Apr 2002
Posts: 19,311
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From: Waterloo, Iowa
Hi Dave
Check carefully first that the ground straps, at engine, frame and firewall aren't loose, missing, or corroded. Also that the gauge panel and anything in the dash has good ground. Electrical strangeness is always a result of stuff hunting for a good ground. If they are original especially or even just kinda old replace them. I bet if you were to test more accessories and turn signals etc there are other faults as well. Could be some defective socketry going on too, but it's something that needs fixed either way.
Check carefully first that the ground straps, at engine, frame and firewall aren't loose, missing, or corroded. Also that the gauge panel and anything in the dash has good ground. Electrical strangeness is always a result of stuff hunting for a good ground. If they are original especially or even just kinda old replace them. I bet if you were to test more accessories and turn signals etc there are other faults as well. Could be some defective socketry going on too, but it's something that needs fixed either way.
Lead Driver
Joined: Jan 2019
Posts: 5,081
Likes: 865
From: N.W. Alabama
this tells how to test positives/grounds
Classic Broncos .com - Tech: Basic Vehicle Electrical Diagnosis for 66-77 Early Ford Bronco
Classic Broncos .com - Tech: Basic Vehicle Electrical Diagnosis for 66-77 Early Ford Bronco
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5th Wheeling
Joined: Sep 2018
Posts: 25
Likes: 0
From: San Diego
this tells how to test positives/grounds
Classic Broncos .com - Tech: Basic Vehicle Electrical Diagnosis for 66-77 Early Ford Bronco
Classic Broncos .com - Tech: Basic Vehicle Electrical Diagnosis for 66-77 Early Ford Bronco
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
And even though it might be a long shot (unless you have dual exhaust?) you might just run your hand along the wiring loom on the driver's side frame rail, or wherever your main bundle runs to the back.
If you have some kinked, burned, cut or otherwise compromised wires in the back you might simply have a small short-circuit going on.
I agree with all the grounding suggestions. Weirdness is almost always a ground issue. But when you hit the brakes, the brake lights come on whether the key is ON or OFF, and at some point a brake light wire is probably very close to the fuel sender wire(s).
Do you have dual tanks, or a single? If duals, which position is the switch in, and if you flip the switch does the madness with the gauge still happen?
Paul
If you have some kinked, burned, cut or otherwise compromised wires in the back you might simply have a small short-circuit going on.
I agree with all the grounding suggestions. Weirdness is almost always a ground issue. But when you hit the brakes, the brake lights come on whether the key is ON or OFF, and at some point a brake light wire is probably very close to the fuel sender wire(s).
Do you have dual tanks, or a single? If duals, which position is the switch in, and if you flip the switch does the madness with the gauge still happen?
Paul
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5th Wheeling
Joined: Sep 2018
Posts: 25
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From: San Diego
Thanks to all who have responed. Two tanks and yes it happens no matter which position the selector switch is in front or rear. PO Installed electric brake controller(the job looks clean) and when I push the activate button with or with out trailer hooked up,gas guage gos up..no other gauges seem to be affected. Unplug sellector switch gauge dosnt move when brakes are apliad or trailer brake switch is pushed,keep switch unplugged,turn on ignition fuel gauge gos way past full.
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