Brake lights
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Brake lights
Hello everyone,
I have a 1978 F150 4x4. I haven't had the chance to drive it much. I bought it when I was away from the country and when I came home it fired right up. I drove it around for a couple days. The next day I tried to start it and the battery was dead, I got it jumped and discovered that the brake lights were stuck on. I first adjusted and then replaced the stop light switch at the pedal with no result. I started tracing the harness out, found some corrosion on the trailer light plug so I took that off (PO did a shoty job installing it). After removal I had some shorts in the rear light harness so I made a new harness with shrink wrapped connectors and new sheathing. It got rid of the shorts however my brake lights are still stuck on. I think it might be from somewhere in the turn signal power supplies because when I turn on either blinker the applicable side brake light will go out but not flash and the front lights do not flash either. Could this all be caused by a bad flasher relay? Or the turn signal switch its self? Any help would be appreciated! Thanks
-Matt
I have a 1978 F150 4x4. I haven't had the chance to drive it much. I bought it when I was away from the country and when I came home it fired right up. I drove it around for a couple days. The next day I tried to start it and the battery was dead, I got it jumped and discovered that the brake lights were stuck on. I first adjusted and then replaced the stop light switch at the pedal with no result. I started tracing the harness out, found some corrosion on the trailer light plug so I took that off (PO did a shoty job installing it). After removal I had some shorts in the rear light harness so I made a new harness with shrink wrapped connectors and new sheathing. It got rid of the shorts however my brake lights are still stuck on. I think it might be from somewhere in the turn signal power supplies because when I turn on either blinker the applicable side brake light will go out but not flash and the front lights do not flash either. Could this all be caused by a bad flasher relay? Or the turn signal switch its self? Any help would be appreciated! Thanks
-Matt
Moderator & parts slinger
Joined: Feb 2007
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From: S/W Missouri, Polk county
Are your brakes themselves coming off when you release the pedal? Since you adjusted the switch I would say yes.
Yes maybe bad flasher or bad t/s switch. You definitely have some wiring issues going on.
https://www.ford-trucks.com/forums/1...ml#post1812190
Yes maybe bad flasher or bad t/s switch. You definitely have some wiring issues going on.
https://www.ford-trucks.com/forums/1...ml#post1812190
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The lights stay on when the pedal is released, yes, but no they do not go out when the pedal is depressed they stay lit. The brakes themselves do release when the pedal is released. I went through all the wiring and it's all original except for where the trailer light plug was spliced in and I went through and rewired that whole portion.
Hotshot
Joined: Apr 2009
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From: Stanley, VA
When you unplug the brake light switch, do the brake lights stay on? If yes, then that means they are being fed after the switch. You'll need to trace the wiring. My first suspicion would be something in the turn signal switch.
One thing I would check is the wiring for the t/signal switch. I've seen several times where a PO couldn't figure out how to get the wires out of the column and cut them, then did a p**s poor job of splicing them back together and the wires shorted together.
NOTE: I think you'll learn very quickly that one of the worst things that could happen to our trucks is a "previous owner".
One thing I would check is the wiring for the t/signal switch. I've seen several times where a PO couldn't figure out how to get the wires out of the column and cut them, then did a p**s poor job of splicing them back together and the wires shorted together.
NOTE: I think you'll learn very quickly that one of the worst things that could happen to our trucks is a "previous owner".
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So replacing the DR flasher and the Turn signal switch only relieved me of some old, worn out, and very dirty parts and allowed me to get into some new areas to clean. Will keep tracing the schematics against the wiring harnesses and let you guys know what I find.
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