Brake Lights on 1996 Dodge Ram Come On and Stay On Sometimes when Connected to 5th Wheel Trailer
Question:
I have a 1996 Dodge Cummins 2500 plus an older Fifth Wheel 1985. I had this issue prior to changing the brake controller, the wiring on the truck and fifth wheel and still have this problem. I have had this on many a vacation where at some point the truck and trailer brake lights come on. When I shut the truck off they still remain on. When I unplug the fifth wheel the brake lights go off on the fifth wheel but not on the truck. The only way I have found to cancel the brake lights on the truck is to pull the fuse on the truck for the brake lamp, start the truck, stop the truck and re the fuse. Then and only then does everything reset. I might only be guessing but it seems that this all starts when I have backed up the unit at some point. It is getting so frustrating as I have asked many a mechanic what could possibly have the brake controller activate in this manner. Please help me in any way you can with some suggestions. Have you ever heard of this ever happening? I have never had an issue with the truck solo. This only happens when I hook up to the fifth wheel.
asked by: Brian R
Expert Reply:
It sounds like there is a short or some back feeding through the tow package wiring when the 5th wheel trailer is connected. The easiest thing to check would be the trailer and truck connectors. The need to be clean and corrosion free inside and out. Make sure none of the wires attached to the back of the connectors are touching each other.
It could also be the brake controller. In the truck cab you will need to sever the blue wire several inches from the back of the controller. Then use a circuit tester such as # PTW2993 to test the end of the blue wire coming out of the controller. It should only have power when you apply the manual override or brake pedal. If it shows power at idle, then there is something wrong with the controller and it will need to be replaced.
You can test the brake output pin and it should only show power with the manual override. If it shows power any other time, then there is a short somewhere between the connector and the brake controller you will need to track down.
Check the connection on the brake controller red wire as well. This is the wire the brake controller uses to let it know when you are stepping on the brake pedal. But it will also get power sent down the wire to activate the truck brake lights. If that connection is shorting out that could be the problem. Re-establishing a good connection between the brake controller red wire and the brake switch wire it attaches to could solve the issue.
If your brake controller has a leveler knob, then if it is off even a little it could cause all sorts of weird braking to occur and could be causing this issue. Also make sure the controller is mounted within the range specified by the instructions and make sure it is not tilted or turned to one side.
I have also included some links on testing and troubleshooting brake controllers for you.
Products Referenced in This Question
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Dexter Electric Trailer Brake Assembly - 12" - Right Hand - 6,000 lbs
- Accessories and Parts
- Trailer Brakes
- Electric Drum Brakes
- RH
- 6000 lbs
- Brake Assembly
- Manual Adjust
- 12 x 2 Inch Drum
- Dexter
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