I used to have a '99 Expedition. The first time I tried to pull my new boat with it, the trailer brakes locked up in reverse ( did not do this with the previous boat) until I plugged in the fuse/relay (or whatever its called) to tell the trailer brakes not to do that when in reverse. I will soon be towing that boat with the new 2010 Lariat Screw but have not done it yet. Does this truck also need that part installed? The part in the glove box seems to be for an electric brake controller. I have the regular tow package, no electric brake controller, and surge brakes on the trailer. I'd just go check myself but the boat is still in storage. I will be taking it out soon though and want to be prepared if I need to plug that part in. TIA.

 

It sounds to me like you have surge brakes on that boat trailer which means that if you push the trailer backwards it applies the brakes. I would try backing up more smoothly and slowly. I could be wrong but that's what it sounds like to me. I'm not sure operating without a fuse would ever cause the condition you're describing. It could lead you to having NO brakes, but not brakes in reverse..

 

Problem solved. Yes the trailer has surge brakes. Yes on the old Expedition they would lock up in reverse (uphill or on my rough dirt field) until I added that fuse. The new 2010 Lariat must already have that fuse installed. Real world tested by backing up in my field>>>trailer brakes lock up in reverse IF the trailer lights are not plugged in. Plug in the trailer lights and I hear the whooosh of the trailer brake piston releasing as the truck override mechanism tells the trailer it's OK. The Expy would not talk to the trailer until I installed that fuse (I bought it but I think it may have been the one that was in the glove box of the Expy all along). The F150 must already have it installed.

 

Rogue14,
I have a 2000 expedition and I have the same issue. I've got my manual for the expedition out, but it's not too clear on fuses. Can you tell me what fuse and fuse location you put it in to make it work? My manual leads me to believe it would be a 30A fuse in location 108, but that fuse looks fine.
Thanks!