Just like the title says, last night I noticed a head light was out so I picked up new bulbs today. When I finally got the headlamp out I pulled the old bulb and noticed that the bulb seemed fine. I replaced it and turned the lights on manually and nothing, the driver's side was on just fine. I switched it to high beams and still nothing on the passenger's side except for the marker light/turn signal. fuse $6 was good, in the in cab fuse panel. What do I look for next?

 

I would say check the ground if the lo & high don't work.

L & R Lo are 2 different fuses, but high is the same ( on the F-150 it is, I am making an assumption here, which could bite me in the rear ).

 

#23 is right hand low beam, #25 is left hand low beam, #35 is high beams. Check the ground for the side that's not working.

 

If it's just the one that sticks out of the loom behind the housing and goes to the core support it appeared fine.

 

The manual says if one whole side (lows and highs) is inoperative, then to repair circuit 57 (BK), which is the ground circuit. It's the only "solution" it gives.

Hold up, lemme go check my plug, to see which one is the ground wire...

 

Pins 1 and 3 are grounds. 2 is not. If you take a multimeter, set it to check continuity (mode where it beeps if you touch both leads together). Put one lead in the pin, touch the other to the negative post on the battery. Pins 1 and 3 should beep, and 2 should stay silent.

This is done with the headlights off.

 

Thanks, I'll have to borrow a multi-meter and check it out.

 

I'd just go an buy one. The basic ones aren't that expensive (maybe 10 bucks), and they come in handy a lot.

 

I should have one in my tool box. Any recommendations?

 

I picked one up, now, what relay is that and where is it located?

 

It's the connector behind the headlight. Take out the headlight, and there should be 2 plugs, that one^ and the one for the parking/turning light.

 

That is the headlamp bulb connector or does this plugs into another harness that separates it to the 9006 & 9005 bulb connectors ? ( Sylvania app guide lists it as these bulb types ).

If so, why are 2 of them to ground, 1 should be ground, the other low beam, the other high beam.

 

It plugs into the headlight, which then splits off into a 9006 and 9005 connector. Not sure why there's 2 grounds, I'll recheck it tomorrow.

 

Well I got zero resistance on one, two, and three, and 0,0,0 on continuity. Now what?

 

Could it be a short? Bad relay? Bad MFS?