White, 1998 F-150, V6, No towing options - Parking lights for the trailer work but not brake lights. I have checked every fuse I can find. Even under the hood. I am at loss to explain this one. Can someone please help?
All lights for the vehicle work fine and This is the only problem I have with the truck.

 

I have a 2001 but I would believe everything would be the same as far as fuses and relays.

In my owner’s manual there is a diagram of the Distribution box (fuse/relay box) for under the hood (page 186 I believe). The following are all found in this box under the hood:

FUSE’S:
Tow backup / park lamps (fuse #5) 20amps
Trailer light left turn/left stop (fuse #19) 10amps
Trailer light right turn/right stop (fuse #20) 10amps
Trailer battery charge (fuse #101) 30amps
Trailer electric brakes (fuse #108) 30amps

RELAY’S
Tow park lamps relay #201
Tow backup lamps relay #203
Tow battery charge relay #302

You most likely do not have all the fuses and relays since you do not have the tow package. If you plan on towing a trailer like a pop-up or something with a battery and/or a trailer with brakes you will want all the above fuses and relays.

For example my truck came with a basic tow package, which was nothing more the 4-pin connector mounted on the back. When I bought my pop-up I needed a 7-pin connector and I had fuse #101 for “battery charge” but did NOT have relay #302 that was also needed in order to provide a charge to the battery.

In your case it sounds like you do have fuse #5 for the park lamps and relay #201 for park lamps. So check and insure you actually have a fuse for your turn and stop lights which would be fuse #19 and #20. You very well may not even have them.

Hope that helps…

 

Working at a marina, I've had to trouble shoot a million of these things. The first thing I'd check is if you have have power coming out of your 4 pin truck plug to the yellow and green wires on the trailer. In other words, see if the problem is in the truck or the trailer. I generaly find more problems in the trailers than the tow vehicles. By the way, do the directionals or 4 way flashers work? They share the same circuit in the trailer as the brake lights.

 

All lights on the truck work as they are supposed to, with the exception of the trailer "Brake" lights. The trailer parking lights do work. It is NOT the trailer. I have tested the connector with a DVM and 12VDC test light and tried other trailers to boot. I am at a loss...
I have checked all the fuses in the inside and under the hood fuse panels and I have swapped relays around (like kinds). No success.

 

I finally found the fuse that controls the trailer lights. It is located (standing in front of the truck) under the hood on the drivers/right side under the hood hinge. There are actually 2 fuses inside their own ~3/4"x3"x4" box. The reason I didn't find it before is because it had tape wrapped around it. I don't know why. Anyway, it's a 20A mini fuse. I hope this helps someone else.
Luther

 

I am having a problem tracking down what is wrong with the electrical system on my truck - 97 F-150 4x4. The running lamps on the truck work but I can not get power to the trailer plug. I do not have the owners manual and figure there must be a fuse or relay that is defective. Can someone please let me know what fuses or relays to check. Thanks in advance. dc

 

http://www.geocities.com/nbssar/000_0376.JPG
Here is a picture of my truck. The fuse box is mounted on the inner fender well, between the 2 larger fuse boxes and the firwall. In the picture, it is under the small square and circular holes in the inner fender well. It is black plastic ~1"x4". Hope this helps.
LutherP

 

Thanks Luther for the info. That is where the problem was - I wouldn't have thought of looking in an additional fusebox from the larger ones. Thanks again I hope I can be of assistance to you someday.
dc