Headlights not working

ANDREWJ

MEMBER
2004 FORD F-350
10,000 MILES

Please help headlights will not come on but my parking lights will work, but the headlights will not come on on my truck, please send diagram or do we need to troubleshoot a module and if so where is it located. Yes when you pull the dimmer switch back the head lights will come on, and yes the fuses have been checked and are okay,
Then the headlights go out I've replaced the headlight switch, ignition switch, relay. Still can't find the solution.

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
42,822 POSTS

Hello,

It sounds like you have a head light relay or a DRL relay (2nd diagram) that has gone out, Here is a wiring diagrams(below) and some guides so you can do some testing and get the problem fixed. There are several fuses involved with the lighting system, be sure to check them all with a test light

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

and

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Please run some tests and get back to us we are interested to see what it is.

Cheers, Ken

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