continuously blowing fuses
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From: Wallaceburg On.
continuously blowing fuses
I have developed an electrical problem in my 78 f250 4x4 I6. I bought the truck about a year and a half ago and experienced the usual problems associated with old wiring and a truck that was sitting for some time. I had replaced a number of wires, upgraded connections etc and all was well for the last six months. In the last few weeks though I continuously have been blowing fuses. the fuses are for the brake light-emergency flasher, the interior light, now the turn signal flasher fuse has blown twice in two days. I replaced the turn signal fuse again today now they wont work at all. Am I overlooking a ground problem common to all these circuits which are separate from each other at the fuse panel. Where should I start guys, you have never steered me wrong
Thanks in advance
Greg
Thanks in advance
Greg
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From: Virginia
I am not sure about the interior light fuse. According to this diagram
http://www.autozone.com/images/cds/g...3d800ce985.gif
the courtesy light circuit is it's own, so it may be a seperate problem.
But, the brake light circuit and the turnsignal circuit are related. Both of these circuits are fed into the turnsignal switch. The rear brake light bulbs are also the turnsignal bulbs. The turnsignal switch mixes these various signals together depending on what direction you are going in, and if you are stopping or not.
So if we take the above as a clue, we can possibly narrow down the problem to the wires that leave the steering column and go to the rear lights, since this wiring is common to both circuits that are blowing fuses. I would look over the wiring very carefully along the full length of the frame rail. and up to the firewall. I would then also look around the brake pedal area and trace the wiring up the steering column to where it goes into the switch. Hopefully somewhere along the way you will see a damaged wire.
http://www.autozone.com/images/cds/g...3d800ce985.gif
the courtesy light circuit is it's own, so it may be a seperate problem.
But, the brake light circuit and the turnsignal circuit are related. Both of these circuits are fed into the turnsignal switch. The rear brake light bulbs are also the turnsignal bulbs. The turnsignal switch mixes these various signals together depending on what direction you are going in, and if you are stopping or not.
So if we take the above as a clue, we can possibly narrow down the problem to the wires that leave the steering column and go to the rear lights, since this wiring is common to both circuits that are blowing fuses. I would look over the wiring very carefully along the full length of the frame rail. and up to the firewall. I would then also look around the brake pedal area and trace the wiring up the steering column to where it goes into the switch. Hopefully somewhere along the way you will see a damaged wire.
Posting Guru
Joined: Sep 2003
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From: Northeast LA
i'm not trying to hijack the post but i have the same problem with mine! and in testing all the connections and inspecting wires i found out that both of the positive connections in my driver side rear turnsignal are getting 12 volts with even just the parking lights on. i looked at all the wires from the rear of the truck to the front and they seem fine. but the turnsignal cam was broke and i replaced it with one of the HELP ones from advanced. anyway that didn't help any! in utilizing the tech article on the site i'm pretty sure the whole turnsignal switch needs to be replace because years ago the switch on the brake pedal lever got to where it didn't work and the brake lights stayed on and got so hot that it melted the lens cover. so i think that combined with the dash cluster turning to powder and no lights in it working. i think the signal may have gotten damaged. i have replaced the dash cluster and the lights work but the arrows for the blinkers don't light up. and now it has started to blow the fuse as soon as it blinks one time!! does it sound like the whole switch is bad to you?
thanks
jason
77 f100
thanks
jason
77 f100
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Joined: Jan 2001
Posts: 56,984
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From: Virginia
The switch going bad usually does not cause a fuse to blow. Frayed wires in the column would cause the fuse to blow.
This sounds like a bad ground at this light. If the ground is bad, or the socket is bad were the ground connection is made to the bulb, then power from the running lights will run backwards up through the brakelight circuit. You will get 12 volts on both wires, and the running light will go out if you press the brake.
in testing all the connections and inspecting wires i found out that both of the positive connections in my driver side rear turnsignal are getting 12 volts with even just the parking lights on.
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