My 1984 Ford F-150's headlights went out this morning. Pretty sure it's a blown fuse...no idea where the box is. Looked at some diagrams, can't figure it out. Anyone know? How about which fuse is the right one for headlights? Help is greatly appreciated!!! ))

Maybelle'84

 

The headlights are not fused. The only thing they have is a fusible link over at the pass fender under the hood.

The best thing to do is get a testlight or voltmeter, turn the headlights on, and probe the dimmer switch in the floor. If you have voltage on one of the wires at the dimmer, then the headlight switch is ok, and it might be the dimmer switch if you do not have voltage on any of the other two wires.

If you do not have any voltage on any of the wires at the dimmer switch, I would pull the dash and check the headlight switch itself.

 

Thank you so much!

Maybelle'84

 

A funny thing happened to me once. I had a headlight go out in my truck, so I replaced it. Two days later, when I went to leave a friends (at 11pm), both of my headlights went out when I turned them on. After searching high and low for three days, I found the problem. Both headlights blew out at the same time. It was time for the old one to go out, and the new one was defective. I replaced them and have had no issues since. From now on I will always replace the headlights in pairs.

 

The Headlamp switch is on a circut breaker. This will cause the lights to Flicker or flash on and off, but wont let the lamps go completely out when there is a short circut or defective headlamp switch.

The dimmer switch would be the first thing I would check as well. Wet feet and corrosion are very common cause of dimmer switch failure.

 

Hi
I pretty much have the same problem right now, checked the dimmer switch connection and and the contacts are corroded. I will replace the switch and see if that brings it back. I have no low or high beam . This has to be the problem .

Dave

 

Got all lights back working, just cleaned up the contact points at the dimmer switch and the connection. Back in business.

Did you get yours working maybelle'84?

 

Dave thanks for letting us know what got your lights back on.
As DaveF said if you check and have power on 1 wire at the dimmer and no lights high or low beams it is most likely the dimmer switch as you found.
The only other thing would be 2 bad bulbs at the same time.
Dave ----

 

I learned something , I went looking for a fuse too when both lights went out at the same time. Both close to brand new btw.
The dimmer switch itself was ok but I gave all contacts a good cleaning , all good now and it didn't cost me a dime.

 

That is the best kind of fix
Dave ----