Hi all,
I have a 2001 F150 4.6 and here is my issue if this makes sense...(headlight bulbs are fine) but I'm trying to see why:

1. When I turn on headlight switch (normal) the left headlight ON-right headlight OFF
2. When I push lever forward for bright lights the left headlight goes OFF & right headlight comes ON
3. When I pull lever back towards me both headlights ON

Why is this happening?? any suggestions

Huddle

 

Sounds like maybe some wires are crossed inside the fitting that connects to the headlight.

 

Ok thank you,
I will check that.

 

There's probably nothing wrong with your headlight wiring unless a mouse got in there and ate wires.

Park in front of a wall or garage door and observe the actual behavior to confirm light patterns before doing anything else. Could be that you have two bad headlight bulbs. One has a burned out high beam element, the other has the low beam element out. It'd estimate that to be the most likely scenario.

It is also possible for the issue to be at or in your MFS but, like the bulb hypothesis, it also requires to simultaneous failures.

 

Thank you Sir...I will try this first & replace both bulbs.
Are the MFS's hard to replace if needed?

Huddle

 

If you have both lights on with the pass to flash with the lights on it is because the low beam does not shut off with that, if the lights are off and they both turn on then you have a Problem in the wiring or MFS.

 

High beams and flash to pass are working. I replaced the MFS. When I connect connectors #4 and #5 on the black plug that goes into the back of the headlight switch, nothing changes, so I am narrowing it down to wiring.

Which means given my time available, knowledge base, and experience I will be taking it to my shop.