Repairing Intermittent Short on Trailer Brakes

Question:

Have an 87 Alpenlite 5th Wheel. It has 4 what i think are Hayes electric brakes. The magnets are round 2.25 inch diameter and look exactly like Tekonsha 5105 magnets but Im not sure. The drums are 10 inch. Ihave not been able to find any info on this old trailer. I get an occasional short message on my prodigy controller and an over load at the same time.. I have tested the amperage on all magnets which is 3.4 ..also tested them for shorts and cant find one.... my next test will be the amperage test between trailer and truck ...2001 f 250 7.3 ltr. diesel . I have a problem with the trucks emergency brake idiot light ...Couldthis cause a short or be the source? Im no electrician but Im learning

asked by: Jeremy

Helpful Expert Reply:

Worn brake magnets, corroded or damaged trailer connectors and a short in the brake wire on the trailer are the most common causes of the OL (overload) error message on your brake controller.

Examine the trailer connector on the vehicle and the trailer. Look for damage or green/white corrosion on the pins or in the sockets. Clean or replace as necessary. Trace the brake output circuit on the trailer from the trailer connector rearward to the brake assemblies. Look for pinched wires or loose connections. Look for worn or cracked wire insulation. Make sure the connection at the brake magnets is secure. One magnet wire should ground securely to the trailer frame, the other should connect to the brake wire.

Next, check the brake magnets. Pull the hubs off and examine the face of the magnets that would ride against the armature surface of the brake drum. If the face of the magnet is worn to the point where you can see the interior copper wiring, the magnets need replacing.

The amperage you provided seems pretty low, indicating that the leads on your magnets are most likely bad.

I searched for a replacement magnet for your Hayes brake assembly, but found out that the replacement magnets have been discontinued. I'd recommend replacing your brake assemblies with 10 x 2-1/4 inch etrailer.com self adjusting brake assemblies like # AKEBRK-35R-SA for the right side and # AKEBRK-35L-SA for the left. I cannot find the Tekonsha magnets you refer to, so I couldn't say if they'd be compatible or not.

The vehicle and the trailer braking system are only connected through the stoplight switch circuit. I'd be very doubtful that the trailer brake issue is causing the emergency brake warning lamp to illuminate. I've linked you to some FAQ articles that you might find helpful.