Trailer Fault message

[Montana5]

We recently completed a 3000 mile trip in our 3000RK pulled with a Ford 250 HD. Three times during the middle part of the trip we got a trailer fault message. The messages did not stay on long and did not appear to affect the brakes. The truck owners guide says the problem is related to trailer wiring, either a short to ground or a short to voltage i.e., a chaffed wire. Any suggestions about how to verify?

[camper4]

A short in the wiring is common. Usually where the wires enter the axle to go through to the other side's brakes. Carefully check the wire at those entry/exit holes for worn insulation. I had that happen to me, different controller, but same results.

[Tom S.]

You'll need to pick up either a meter or a continuity tester. I recommend the meter because it's much more versatile. You don't need to spend a hundred bucks for a really good one, but I would hesitate to buy a $5 Harbor freight one too. Disconnect the truck batteries, then use the ohm (resistance) setting to test each wire to see if any besides the ground wire give a "0" reading, which indicates a short. Then unhook the trailer battery and shore power and repeat the process for it. The problem with intermittent problems like this is getting them to act up while testing. One thing that may help is to have a helper (aka wife) jiggle the wires while you are testing them to see if you can replicate the problem. Like camper4 said, pay attention to the brake wires under the trailer because wear from chaffing is fairly common.

One last thought, a loose and/or dirty plug can raise heck too, so I would also clean both the male and female plugs, make sure they are plugged in securely, and see if the problem comes back.

[stiles watson]

When I had this problem, it was an issue with the wiring harness to the bed of the truck. Water had gotten into the connection underneath at the point of connection. It was rewired and sealed. That was three years ago, so I guess the fix worked.

[oldelmer1]

I remember reading that ford has a TSP out for the 2007 - 09 for the 7 pin connector. Seems the back is not sealed and when it rains, the connectors get wet and can short out. My 06 had the same problem. The wire harness plugs into the 7 pin connector, when I unplugged that connection, water ran out. Cleaned it all up, coated everything with dielectric grease and sealed the back of the connector(where the wires from the harness plugged into) with sealant.

Of course, after all the above work, this didn't fix my problem, replacing the 7 pin head on the end of the trailer cable did.

[Debbie Asher]

We had a short in our brakes on the trailer from the wire chaffing on metal. The wiring wasn't wrapped very good and had been cut from rubbing.