Need help! headlights dont work
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Freshman User
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Need help! headlights dont work
77 F250 was installing headlight relay harness from bronco graveyard yesterday and now i have no headlights. Eliminated the new harness and plugged a headlight into the factory plug and still doesnt work so not a problem with the harness. No power at the factory plug checked w a test light. Anything i should check first? Fuses looked good but will test them tonight. Running lights work fine. Also noticed my cluster doesn't light up now???
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Joined: Aug 2010
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From: Knoxville, TN
Good point. I caught the lack of dash lights but missed the running lights. 
I'd check the voltage at the various wires in/out of the switch and see what you do and don't have there - the fact that you lost the dash lights too is suspicious. Makes me wonder if you somehow shorted something when installing the harness and damaged the switch when you tried to turn it on the first time.
I'd check the voltage at the various wires in/out of the switch and see what you do and don't have there - the fact that you lost the dash lights too is suspicious. Makes me wonder if you somehow shorted something when installing the harness and damaged the switch when you tried to turn it on the first time.
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Just went out to the barn. Turned on headlight switch nothing but running lights. Stepped on the bright switch and they turned on! Now seem to be working fine on high and low. Think my high beam switch may be bad?
Fleet Owner
Joined: Dec 2009
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From: NorCal
YES....... IIRC, voltage still goes through it with low beams.
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Posting Guru
Joined: Jan 2005
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From: Douglas, Georgia
Sorry I forgot about this thread for a month....
Yes, the dimmer switch (hi beam/lo beam switch) is dying.
Bout all the lights run through that switch, and well, simply put it is a good place to start seeing how its on the floor, and often the most abused due to moisture and dirt.
DO change it, even if it works now, at the most annoying time it'll die again.
I've had to drive home before at 3am with nothing but hi beams :P
Pro-Tip:
Do not buy the autozone switch, or any low quality switch, they do not last very long in many times. Buy an NOS switch or other high quality unit, they'll last a very very long time (Ebay or Dennis Carpenter is the best bet).
Yes, the dimmer switch (hi beam/lo beam switch) is dying.
Bout all the lights run through that switch, and well, simply put it is a good place to start seeing how its on the floor, and often the most abused due to moisture and dirt.
DO change it, even if it works now, at the most annoying time it'll die again.
I've had to drive home before at 3am with nothing but hi beams :P
Pro-Tip:
Do not buy the autozone switch, or any low quality switch, they do not last very long in many times. Buy an NOS switch or other high quality unit, they'll last a very very long time (Ebay or Dennis Carpenter is the best bet).
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