trailer turn signal and brake lights don't work
 

My trailer turn signal and brake lights stopped working. no current to the plug at the trailer hitch for the turn signals or brake lights. I went thru the manual and checked all the fuses that related to the trailer lights and replaced them eventhough they looked good. My next step was to replace the Multi Function Switch (MFS) but I don't want to tear it apart unless I absolutely need to. I read a post where an individual solved the problem by locating a fuse not listed in the owners manual, unfortunately, I can't email the individual for more details because I'm new to the site. Anyone have any ideas?

smathewson

Make sure you have a good ground wire going to the trailer. Sometimes people rely on the trailer hitch and ball making good enough contact to produce a ground between truck and trailer and this doesn't always happen. I'd check the ground between truck and trailer first.

in reply to Kingranchman02, I have a 1997 black F 150, 4x4, 5.4 L V8,with a towing package with 74k miles. The ground wires on the truck and the trailer were the first items checked, cleaned, brushed, etc.

Did you check the fuses under the hood?

Mike

I checked the fuses under the hood that were related to the trailer, per the owners manual and replaced them.

My 97 Explorer has trailer tow relays under the hood in in the aux relay box.

I suspect yours is the same, have you checked them?

Check them all. I wouldn't replace them if they aren't bad. I'm sure that Ford ran something with the trailer lights through something else that wouldn't normally be related to the trailer lights.

Normally if my lights don't work, it's because I've blown a 10 amp fuse under the hood. It's close to the front of the box.

Mike

Thanks for the advice. You were right "BLK94F150" and "87 XLT", I found a little 2 fuse box with a 20 amp fuse blown. My owners manual had it shown in a different spot and my Haynes manual was worthless. Lights are now working. I can now continue on my quest to trailer my 67 mustang conv. to the paint shop.