Electrical problem
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Joined: May 2004
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Electrical problem
My 77 F150 tail lights will not work.
Brake lights work when lights are off. No tail lights or break lights when headlights are on. All lights work when the trailer is hooked up except when brake pedal is pushed tail lights go out. All lights on the trailer still work properly.
Replaced all bulbs, fuses, and switches. guess it`s a ground but have no clue where to locate. have not been able two after 4 hours w/ a test light.
ANY CLUE`S TO WHERE TO START??
Brake lights work when lights are off. No tail lights or break lights when headlights are on. All lights work when the trailer is hooked up except when brake pedal is pushed tail lights go out. All lights on the trailer still work properly.
Replaced all bulbs, fuses, and switches. guess it`s a ground but have no clue where to locate. have not been able two after 4 hours w/ a test light.
ANY CLUE`S TO WHERE TO START??
New User
Joined: May 2004
Posts: 1
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I'm also having the same problem with my 77 F150 but not only do i have the headlight on tail lights off problem but when i turn my blower fan on my wipers turn off i have no idea what to do about it please if you find anything out let me know
Postmaster
Joined: Nov 2003
Posts: 3,595
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From: Utah County, UT
Follow your wiring harness off the lights, sounds like you melted some wire together, or your are driving both side of the lamps with 12v when the brakes are pressed. If you have an OHM meter, if not recomend getting a cheap one, disconnect battery and start ohming out wires, keep a note book handy and wite down what comes up. With the lamps remove, you should get an open between all wires and ground, except ground of course. Then do the same again with the light switch on marker lights, then with the switch on all, then have someone hold or wedge the brake down. One of those is going to be leading to a short, either to ground or another wire. Good luck...
Mike
Mike
Moderator
Joined: Jan 2001
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From: Virginia
Originally Posted by pyromedic
My 77 F150 tail lights will not work.
Brake lights work when lights are off. No tail lights or break lights when headlights are on. All lights work when the trailer is hooked up except when brake pedal is pushed tail lights go out. All lights on the trailer still work properly.
Replaced all bulbs, fuses, and switches. guess it`s a ground but have no clue where to locate. have not been able two after 4 hours w/ a test light.
ANY CLUE`S TO WHERE TO START??
Brake lights work when lights are off. No tail lights or break lights when headlights are on. All lights work when the trailer is hooked up except when brake pedal is pushed tail lights go out. All lights on the trailer still work properly.
Replaced all bulbs, fuses, and switches. guess it`s a ground but have no clue where to locate. have not been able two after 4 hours w/ a test light.
ANY CLUE`S TO WHERE TO START??
