Trailer Brake Light Issue 98' Explorer

[madbrown]

Been having issue with the driver side brake light on my boat trailer. Turn signal & headlight work but no brake light on trailer, butbrake light works on explorer. Tested the wiring on the trailer and everything is good there. Swapped lights, bulbs, etc., and everything checks out there. Followed the bad wire up into the back of the vehicle and then disappears into the body of the vehicle appears to drop down by back seats. Is there a poss. of a bad relay somewhere??

 

[tanbuddy]

Check the fuses, i had a similar problem in my exp

 

[madbrown]

Fuses and bulbs are good in vehicle & trailer.

 

[bobflood]

Been having issue with the driver side brake light on my boat trailer. Turn signal & headlight work but no brake light on trailer, butbrake light works on explorer. Tested the wiring on the trailer and everything is good there. Swapped lights, bulbs, etc., and everything checks out there. Followed the bad wire up into the back of the vehicle and then disappears into the body of the vehicle appears to drop down by back seats. Is there a poss. of a bad relay somewhere??

Wiring diagram shows a relay for the parking lights, but none for the brake lights. Brake and directional come out on a single wire form the MFS, thru the fuse box (fuse #7, 7.5A), and out to the trailer adapter. Left side is a yellow wire from fuse panel. Strange that left directional on trailer would work, but not left brake on trailer. I am always suspicious of the **** MFS whenever it is anywhere in the circuit.

 

[madbrown]

Mfs?

 

[bobflood]

Mfs?

Sorry - Multifunction Switch. It's the switch on the steering column that controls headlights, directionals, flasher, etc. Often a source of trouble on these vehicles.

 

[Joe Dirt]

I had to physically ground the lights on my boat trailer to the trailer frame in order to get it to work. Ran a jumper from the light to the frame of the trailer. Make ure your ground by the tongue is strong as well.

Went through 3 sets of bulbs, and 2 trailer wiring harnesses to find that out. The one light had the plate thing on it, which was plastic. The light was mounted to it. The screw on that light housing should have been the ground wasn't attached to metal, so it wouldn't work correctly. When I ran a wire from that bolt through a wire on the trailer frame it worked. Mine was a bad brake/turn on that light. The only thing that worked were the parking/running lights. Activating the signal would flash, but it was alternating the running light off and on. Press the brake and the light went off altogether.

Sounds like a slightly different issue, but you might try a wire touching the bolt and the frame...