ok so my dads 2005 ford f150 xlt has a problem with the taillights the only time the bulbs illuminate is with a blinker and pressing on the brake and when you use your hazards so when your driving down the road at night it wont light up unless you use your brake or blinkers etc. I HAVE CHECKED ALL FUSES. i cant seem to figure out what the deal is my suspicion is that the light switch on the dash is messed up i really need your help with this one

Thanks, Josh

 

I have to ask, did you try replacing the bulbs?

The bulbs have 2 filaments to them, 1 for brake/blinker/turn, and 1 for running lights. There is a chance that the filament for the running lights has blown and the blinker filament still works.that requires replacing the bulb. If you have replaced the bulbs and it didn't fix the problem then its time to get out the multimeter and either work your way from the switch to taillight or vice versa to find out where the wiring problem is.

 

Same issue on my 98 F250 LD. Afraid it's the wiring. How did you solve this issue?

 

What he said.