My headlights have started turning off and on randomly. At first it was only when the brights were on but last time I drove the dims started doing it too. dash and taill lights stay on and turn signals still work. any suggestions on were to start looking?

1990 f150 5.0 5spd 4wd

 

Year? Engine? Model?

 

1990 f150 5.0 5spd

 

added info to post.

 

Having all the info may help you get the answer you need. Sorry that I cant provide you with the answer though.

 

Probably a bad headlight switch

 

I've seen that frequently, so far it has always been the dimmer switch.

 

Found the problem, the connector to the headlight switch was burnt. I replaced connector, switch and dimmer switch. seems to be working now.