trailer brakes come on when my 4 ways are on

[trampsdieseltruck]

i pulled a friends 5th wheel trailer today all lights were working.when i went to back it off of the street into his driveway i put the 4 ways on and we came to a stop when the trailer brakes came on.i thought it was his trailer but on the way home empty i put the 4 ways on and the light came on the brake controler.i tried the right signal nothing,the left signal nothing,4 ways and the light came on.where should i be looking to fix this

[burnetma]

Yes, this is an issue unique to the wiring of the older F-Series trucks. I had that problem on my 1990 F250. It required an alternate wiring set-up, but I can not remember the details (sorry!).

Try doing a search or ask the question of the early 1990's forums.

[nashvillebill]

It's not really the truck's problem, it's the controller. Add this Pulse Preventer for Electric Brake Controllers 5501 : Trailer hitch bike rack and trailer hitches - etrailer.com to fix the problem.

[Bill1013]

Yup. The 4-ways trigger the brake lights which in turn triggers the brake controller. If you are going to pull mountains where slow speed requires you to use the EM lights then you need the pulse preventer like nashvillebill said.