Troubleshooting Trailer Brakes That Stop Working When It Rains

Published 10/25/2019

Question:

When raining and pulling my 2014 Montana fifth wheel with my 2016 3500 ram I get a alert that I have no brakes check trailer wiring or trailer disconnected. After it stops raining they come back on. They work good when dry. It show no gain when you hit the brakes but only when raining. It stated after I had new spring put on the Fifthwheel. I have the wire to rewire the axles, wondering if I should change the trailer emergency disconnect switch and the 7 blade male end with wires to the junction box?

asked by: Wayne B

Expert Reply:

I'll start this off by saying that I don't think the issue has anything to do with the breakaway switch or junction box, It sounds to me like the rain is causing a short on your wiring and this is what is causing your brakes to go out; since you just had new leaf springs put on the 5th wheel trailer it's possible that something was damaged during the repair process.

I would first examine the ground wire connection on your trailer-just because that's an extremely common cause of shorts like this. Once you've checked the ground, you'll want to start looking in the area of the frame near the springs for damaged wires that run to your brakes; ultimately you'll want to check the entire length of the brake wire (usually blue) but since you just had some repairs done in that area it's possible that a wire got nicked during the process and it's causing the short. You'll want to look for any frayed or cut wires that would be exposed to water when it rains and replace the wire as needed.

If you haven't located any issues on your brake wire, make sure that none of the wiring on the breakaway switch and junction box is damaged, as well as checking the trailer connector for any issues such as corrosion, loose connections, etc.. If you can't find an issue on the trailer side, I would have a look at the vehicle side to make sure that the (blue) brake wire on the vehicle hasn't been damaged in the same manner you did on the trailer.

If all of these steps still haven't located any problems, let me know and I can give you a couple of other issues to have a look at.

expert reply by: Erik B