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Flashing lights and voltage drop.


constant_projecttruck

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(reposted here as it is the lights for sure)

Okay I got a weird one here boys.

Well. Two days ago my right rear turn signal and brake light stopped working but the running light still works. When I would turn the signal on I would get a very small voltage drop but no light. Now tonight when I was about to leave the same thing is happening to ALL my lights. Interior, all exterior, and gauges. I turn the light switch on and the interior lights (guages) only come on for 2 - 5 seconds then ALL the lights start flashing randomly (not as a hazard light) and there is a huge voltage drop (below 10 volts) to the point where it idles very rough.

I have had experience with a crossed wire setting offf all lights to hazard flash but not this. I am thinking a ground somewhere but that wouldn't cause a voltage drop somewhere would it? I need help as I have a fishing trip and I will be driving at night.
 


constant_projecttruck

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UPDATE!!!

So I tore in to the dash (I hate repairing 1st gen dashes) and it is the main power to the light switch. It is the tan wire (not green) at pin b2 on the connecter. I checked the fuse and it was blown. It was a 15 amp fuse that blew so I replaced it with a 5 amp. The connecter was also melted (see 1st pic). I plugged it all back together with a new headlight switch and 5 amp fuse and the same thing happened. When it flashes I can feel the new light switch "click" and it gets hot after a while.

The old light switch was burnt on pin b2 (see 2nd pic).

I ran my aftermarket guage lights off the dimmer wire (red/yellow) but nothing else has been done to the wiring of the switch.

I have read other threads but don't seem to be same problem. My lights won't stop flickering/flashing after they start flashing. It seems like a short to me but any other ideas before I start searching through the wiring.

PLEASE HELP! Have to drive at night in 2 days.


 
Last edited:

RobbieD

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The light switch does have an internal breaker; I suspect that's the "click" that you're hearing. It sounds to me like you have a lot resistance in the circuit, or, a short. A direct short should just blow the fuse; the CB kicking instead leans more toward a very bad connection (i.e.- high resistance).

If it were me, the first thing I'd fix would be toasted light switch connector. I'm thinking you have a crappy wire-to-terminal connection in that connector. Then, go down through the lighting wires in the harnesses, looking for bad wires or a short.

Good luck, man.
 

constant_projecttruck

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Thanks robbie. By bad connection could that be anywhere in the circuit? I have always looked at my headlight connections as suspect but would that qualify?

Any idea where I could get one of these connecters other than a wreckers?
 

constant_projecttruck

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Thanks Robbie for leading me in the right directions. I got it all sorted out. When I changed my oil yesterday (filter relocater beside driver side headlight) I must have smacked the connections together. Everything works perfect now. Thanks again.
 

RobbieD

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Good deal; I'm glad to hear that you got it whooped.

Your questions:
A bad connection causing high resistance anywhere after the switch can throw its breaker. Heat caused the burnt terminals and melted connector, right?; it's an increased current draw which kicks the breaker, but not enough of a dead short to blow the fuse. Scary, huh?
I don't know for sure where you can find new replacement wiring pigtails. Ford used to offer them, maybe still; and perhaps lmctruck has that particular one. I did the boneyard thing for mine, and just slipped out the good terminals, spliced in the couple of needed replacement terminals, and then put all of the wires back into the new good plastic connector body.

Have a good trip, man, and catch us a lot of fish!
 

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