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dpatt67's avatar
dpatt67
Explorer
May 25, 2017

Wheel bearing failure, now no trailer brakes

This last weekend I had a wheel bearing fail and get the whole area really hot. I've taken care of the bearing, but pulling it home I had no trailer brakes. My truck dash said "check trailer wiring", and I already knew that some of the insulation had melted on that brake wire. The fuses look good on the trailer, is there a fusible link or relay that is another "weak link" that I'm missing?
  • check that wire that "some of the insulation had melted on that brake wire".
    That's where I would start.
  • No other fuses etc. Just wire back to the coil magnets inside the drum.
    Clamp-on ammeter would show if each wheel was getting the proper 3 amps.
  • I checked for power on the opposite side and there was none there either. All areas of the hub that the wheel bearing failed have been cleaned up with no effect. There's full peer to all other areas of the trailer from the truck. I know it's obvious that the melted insulation is the problem, but shouldn't that have caused a short elsewhere?
  • TV fuse is good, and even hooked to my other trailer to check, all good. Just like a fuse, there is no power to any of the brakes. Frustrating, and it may have to go to someone else to find
  • Replace the burned wiring first. Then disconnect all of the brake magnets and connect & check them one by one. Some brake systems are wired in a daisy chain. Best to rewire them in a star if yours are not. Failure of wiring on one won't effect others then. Its a pretty simple electrical system, just located in an inconvenient place.
  • As suggested, wiring is usually "daisied". Look at the crimp connector closest to the axle / brake that had the problem. Further, if you go back to your 7 pin trailer plug and ohm meter the brake pins (top two away other side from the "notch"), it should read in the 1-2 ohms at best. Still further, also check the grounds to the frame near the brake / axles... maybe you lost the ground. Related to the "missing ground potential", measure the ohms from one pin on the 7 pin trailer connector to a KNOWN ground. Do the same with the other pin. This test will tell you if your ground in the brake system "made it" back to the plug.
  • dpatt67 wrote:
    I checked for power on the opposite side and there was none there either. All areas of the hub that the wheel bearing failed have been cleaned up with no effect. There's full peer to all other areas of the trailer from the truck. I know it's obvious that the melted insulation is the problem, but shouldn't that have caused a short elsewhere?


    your brake warning is telling you your brake system has an open problem not a short between wires. although a short will cause an open condition. After the wire is repaired you should be looking for any of the things mentioned by others.
    Broken wires, loose connections, blown fuse,etc.
    You have gotten some really good advice the only part of the trailer wiring that will give you that warning is the brake circuit, which is 2 wires and the magnets and all connections on that loop.
    Good luck!! You can do it.
  • Thank you for all your answers. I'll be continuing to look today