Troubleshooting Brake Controller On 1999 Ford F-350 Diesel

Question:

Have a f350 diesel 1999 The three brake lights will come on for no reason when it rains /when it is dry no one in truck. Have replaced the brake switch, trailer connector, sprayed both fuse boxes. Have checked all wiring. Any idears

asked by: Norm

Expert Reply:

It sounds like you have done a lot of the things we would recommend doing to find the problem. You did not say if the brake controller is new or if it is an older model.

You can check to see if the manual override is working on the brake controller. On newer controllers like a prodigy P2, part # 90885, when the manual override is used it will cause the brake lights to come on. If this happens all the time you can check the red wire that goes from the brake controller to the brake light switch with a circuit tester like part # PTW2993 to see if it is only sending a signal when the manual override switch is moved. If it is sending a signal even when the manual override switch is not used, the brake controller is probably bad and needs to be replaced.

expert reply by: Jeffrey L