Posted 2011-08-16 6:06 PM (#136744) Subject: Cant find problem with trailer brakes
New User
Posts: 4
Location: South Carolina
I have a 2005 ford f350 and I use the factory installed brake box. Everything has always worked fine until recently when I realized it wasn't stopping my trailer like it had in the past. Took the trailer and had the works for electric brakes and they still didn't work. If I manually mash the brake box they work but they dont when I mash the brake pedal. However when I mash the brake pedal the brake box lights up the but brakes on trailer dont work. I did have the Ford place check the box and they said it was fine. Does anyone know why its not going from the brake pedal to the box to the trailer. I hope this made sense.
Posted 2011-08-17 12:08 PM (#136764 - in reply to #136744) Subject: RE: Cant find problem with trailer brakes
Elite Veteran
Posts: 802 Location: Tenn/Ala.
Are all 3 brake lights on the TRUCK working?
As Paul said, it sounds as if the circuit between the stoplight switch and the controller isn't activating. Thus it works manually, but not with pedal action. I do not have a wiring diagram for that truck, but there are models where it feeds on the same circuit as the Center High Mount Stop Light (Known as the CHMSL in the service manual). So- if the CHMSL isn't working, on some trucks the trailer brake controller will not activate either.
Cant find problem with trailer brakes
