My headlights are not right, well just the drivers low beam. For some reason the driver side low beam is getting less voltage than the other side. I've also disconnected the plug and checked with a test light and even the test light comes on at very low power. Does anyone have any suggestions?

 

check the ground wire...usually bolted to the rad support area... no year posted so not sure...

 

It's an 09, the ground wire is fine, the high beam shares the ground wire and it works fine

 

I would do an voltage drop across the power wire and see if you are not getting good power

 

I've run a new ground wire, but the light is still dim, I've also changed the bulb and checked the fuses for the lights. Does anyone know if there is a relay I need to check? I've looked in the owners manual but didn't see the light relay. I'd really like to figure this out so I don't have to pay Ford $110 just to look at it.

 

Do a voltage drop before you go chasing that stuff a voltage drop will tell you if anything in the power is wrong

 

I already know the voltage is reduced in one low beam, I just can't figure out why. Both high beams work right and the other low beam works right too. I'm not exactly sure what you mean by "do a voltage drop " like I said the test light I hooked up to make sure I had power would barely light up, that's when I took a closer look at the headlight bulb and noticed it very dim. At first I thought there was no power at all.

 

Is this something new or has it been going on for a while? Also was it a sudden change or did the light gradually go dim?
If it was a gradual change, perhaps check for corrosion in the connector itself.
If I was in your shoes, I would try to get my hands on the diagram for the front harness. Otherwise it's like trying to find an Address without a map.

 

I just replaced the plugs for both lights. Previously I had aftermarket lights that ran off a relay on the side that works. The side that wasn't hooked to the relay was taped up, so I'm not sure when it quit, because it was not in use for 4 years. I just put the stock lights back in and replaced the wiring plugs and bulbs. I even ran a new ground to the side that's not working correctly. I found a left low beam fuse and a right low beam fuse, but didn't see a relay in the book.

If I can't figured this out soon, I might just run another relay to power the low beams, just like I had on the aftermarket lights. But I'd really like to find out what the problem is.

 

have you tested with a multimeter to see exactly how much of a voltage change you have?