I ran into this problem about a month ago and cannot afford to take it to someone. I am not a mechanic but I am handy can do a few things myself.

Here's the issue, I have a 2002 Ford F-150 and my headlights won't turn on at all and the bulbs are not burned out.

If the truck is on when I turn on the headlights the fog lights and dashboard go on but won't turn off. If I pull the fuse out and put it back in the lights go off.

If the truck is off, the headlights won't turn on and the fog lights do turn off.

I have checked all the small fuses under the dash and under the hood and they are all fine.

I'm not sure how to check the bigger fuses. Any suggestions on what I should do? It is getting really annoying that I can't drive at night.

Just to note:
I did pull a trailer the day before this happened, they worked fine after that then the next night I drove and everything was fine but then when I got in my truck 3 hours later this started.

 

Few questions :

1. When you are turning them on, is this the main headlamp switch to the right, or are you turning it to the left to the autolamp position ?

2. Did you do any modifications ( i.e. bambi mod ? )
- If so, did you pull the 5A fog lamp fuse ?

If you have the bambi mod, and pulled a trailer, did you pull the trailer parking lamp fuse ?
- Taking a SWAG that the connector got some corrosion or something in it, and the 7 pin trailer tow adapter battery charge circuit is bridged to the parking lamp circuit in the 7 pin adapter itself. Seen this on newer body style F150, think it would be non applicable on your MY.
Pull the trailer tow fuses anyway if you want an additional test point, this is the electric brake controller ( pigtail up behind the dash ) and the fuses & relays for the brake, battery charge and trailer stop / turn & parking lamps ( 3 fuses & 3 relays for them I seem to recall ). Positions for these fuses & relays are in a thread in the towing & hauling sub forum if you are unsure.

 

1. I turn it to the right left is off, middle is fog lights, right is on. Brights don't work either.
2. I didn't do any mods, I don't have an electric brake system either.

I can check the relays, how do I know if they are bad?

 

another questions came to mind.

How did you test the fuses for the low & high beams ( there are 4 total, 3 for the lights and 1 that feeds the main headlamp switch ) ?

- did you pull them out, stare at them and put them back in, or did you use a meter to test them in the fuse panel, from the pins on the back to a know good ground looking for + VDC.

- Keep in mind you need to have the main headlamp switch turned to on, and the MFS pulled back to the low beam position for testing the 2 low beam fuses, and pushed forward to test the high beam fuse.

what relay are you looking to test ?

 

I pulled them all out one at a time and looked at them. There was one 5 amp fuse blown and I replaced it but it didn't change anything, not sure what it was for. It was in the fuse panel under the dash.

I also attempted to take off the switch but broke the handle. That's when I decided to seek advice before I do something else stupid.

I was asking my cousin about it and he said to check the relay, honestly I don't even know what the relay looks like.

 

try testing the fuses with a meter to test them in the fuse panel, from the pins on the back to a know good ground looking for + VDC.

- Keep in mind you need to have the main headlamp switch turned to on, and the MFS pulled back to the low beam position for testing the 2 low beam fuses, and pushed forward to test the high beam fuse.



If neither side has power, make sure that you are testing the correct fuse(s) with the MFS position. If you confirm low beam on the MFS and both fuses do not have power next it is time to check the fuse for the main headlamps switch.

BTW : did you break the switch before or after the problem came up ?

 

Thanks! I will do this tomorrow and post results.

I broke the switch after the lights went out. Just the **** broke, I snapped it back in but it's upside down.