Hi
I have a 2004 F150 Lariat. The headlights are having issues, and I am unsure where to start. A couple of months ago, when turning the brights on, the headlights would just go out, but not all the time. Then, a couple of nights ago, I was driving along, and my headlights went out all together. They started going on and off randomly, and both sides do it at the same time.

We have the bright white headlights plugged into the stock harness. Fuses aren't blown, no other lights or accessories appear affected, and the and the turn signals still work correctly when the headlights go out.

Fairly new to the Fords, and am unsure about relays or what might be causing this and where to start.

Any help is greatly appreciated.

 

Are they on auto? There is a problem with the BSM behind the back seat that overheats, it's undersized. I soldered a jumper wire to bypass mine and now works great.

If it's not on auto, I'd start with the actual headlight switch itself.
You should check all wiring especially all grounds.

 

Happens on auto as well as manually turning the lights on. All the marker lights come on, just the headlights are affected.

The lights went out this morning before I had driven 50 feet. Then they both came back on, and flickered on and off for the 1km drive to drop my kids off at work.

 

Then, I'd start with the dash switch. I've never taken mine out, but is it sloppy or lose? You may be able to take it out clean with contact cleaner.

I'm sure others will chime in too.

 

Thank you, I will start there. Are there any relays to check?

The brights causing the lights to go out is what throws a curveball for me. Two seperate switches for the headlights and the brights. I was thinking it might be a relay acting up or dirty causing the intermittent outages, or possibly the super white headlight bulbs.

I'll pull the headlight switch and clean it, and try from there.
Thank you.

 

Each headlight has its own relay, so it’s doubtful they would be causing your issue if you’re losing both at the same time.

 

ok, pulled the switch. It looked really clean but spayed some electronic cleaner on switch and harness.The headlights are on currently, but haven't driven it.

When flicking on the brights, the headlights are currently going out completely. Could the brights switch on the steering column cause the lights to go off, even when the brights aren't on?

 

Good possibility... The the low beams turn off when the highbeams come on unless you’re doing flash to pass.

 

ok. Flash to pass acting the same as turning on the highs. The blue high beam light on the dash comes on, and I have read if the blue light comes on the switch is working properly. We are changing the bulbs, to see if they are the problem. Fuses are good. If this doesn't work, I will swap the high beam relay with acc. on relay and see if it works, as they are the same relay.

 

Sometimes it is the simple things. She actually had LED lights with the harness installed. We have only had the truck for a little bit, and the previous owner seems to have "upgraded" various things. I removed the harness and went back to stock bulbs, and now my headlights are acting normal.
Thank you for the assistance everyone.
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