Please help me...... Late 1999 F350 dually 4x4 diesel crew

Brake lights don't work and electric trailer brake controller will not come on w/ the brake pedal.

If I press the manual contol for the brake contoller I get trailer brakes and brake lights for the truck and trailer. If I push the brake pedal no lights ( truck or trailer), no brakes on the trailer.


I have checked all fuses ( under hood and dash) I replaced the brake switch at the pedal. All other lights work and so do the flashers and turn signals, brake lights work, but only with the brake controller manually and it doesn't matter if the trailer is hooked up or not.

What now? Any ideas.

 

Unplug brake controller @ controller & see if that changes anything, then unplug where controller harness plugs into vehicle harness & see if that changes anything. Check the "trailer" fuses also in vehicle fuse blocks. Relay? Master cylinder wires? Just some thoughts.

 

There is still something wrong with the pedal switch. The trailer brake control is applying power to the lightgreen wire when you are manually applying the trailer brakes, and that's making the brake lights operate. The pedal switch should do the same thing, but is not. If someone spliced into the truck's wiring for the brake controller(the lightgreen wire) that would be a good place to look for trouble. Some people's wiring practices are not very good.

 

I have a 97 F-250, my brake controller is properly wired w/ factory plug under dash to controller plug @ controller (w/ no taps or splices purchased w/ controller), the same for my trailer plug on truck (factory trailer harness from FOMOCO). The controller has 4 wires, one is constantly hot (fused), one is hot when brakes are applied, one is ground, and last is hot out when controller is activated w/ pedal or override on controller. There is a wheel on mine to increase or decrease the signal to the electric brakes @ controller.
I suggested unpluging the controller to make sure it is not the problem since you said you checked the fuses already. I know 99 & 97 are different but double check all the fuses for brakes, turn signals for vehicle & trailer harness on your 99. My lights all worked properly on my truck but my utility trailer/trailer plug did not work for a 4 way flat w/ converter once. After spending 1 hour chasing the lights & wires on my utility trailer it turned out to be a fuse on the truck for trailer lights (don't remember if it was running lights or brake/turn). So recheck fuses, controller harness, connections made to truck for controller & trailer plug, then start chasing the brake light harness under dash & hood. I think its a fuse though.