Troubleshooting a Intermittent Overload Error Message on a Brake Controller

Updated 09/02/2025 | Published 06/29/2025

Products Featured in This Question

Tekonsha Prodigy P3 Trailer Brake Controller - 1 to 4 Axles - Proportional

(6648)

$169.94

10 Gauge Wire - Blue Primary - Per Foot

(104)

$1.84

Question:

2004 gmc 2500 6.6. Intermittent overload warning while towing a camper. Started diagnosing truck. Using a plug in checker at the 7 way shows weak light on brakes. Check ground and am getting excessive ohms ready. Removed cleaned and reinstalled all frame grounds I could find. Checked the 6way plug box under the dash and am getting large amount of ohms here too even after cleaning. Can’t seem to pin point where the ground for the controller is. So is the ground the cause of the intermittent overload warning when braking? And where do I find this said ground to try to fix?

asked by: Jen

Expert Reply:

Hey Jen. The intermittent overload warning indicates a short in the brake output circuit. As a first step, you will want to see if the problem exists with the wiring on the trailer or on your Sierra 2500.

Try unplugging the trailer and activating the manual brake switch on the controller like item # 90195 you previously purchased. If you get the error code at that point, it is a pretty good indication that the problem exists on the output circuit between the brake controller and the trailer connector.

You'll want to first check the 7-way connector itself. Make sure it is not damaged or corroded. If you can see white or green corrosion on the trailer connector's pins, there is a good possibility that the corrosion has migrated to the interior of the connector. If you can access the rear of the connector where the wires attach to the terminals, check those for corrosion and repair or replace if necessary.

If all appears well with the trailer connector, sever the blue wire a few inches behind the controller, leaving enough room to reconnect it later, and try the manual switch again. If the error code has disappeared, then the short is in the wire between the controller and the 7-way connector. You'll want to replace the wiring with item # 10-1-1 from the controller to the trailer connector, bypassing the wire that has the short.

If the OL code only occurs when the trailer is connected, then the problem lies with the wiring on the trailer. Check the trailer connector for damage or corrosion. Trace the brake output circuit from the trailer connector back to the brake assemblies looking for broken or pinched wires or loose connections. Examine the wire insulation, looking for worn or cracked spots that would allow the copper conductor to contact the trailer frame or other metal. Make sure that one lead from each magnet ties into the brake output wire, and the other grounds to the trailer frame. If all this checks out OK, your magnets might be worn. Pull off one of your hubs, and examine the face of the magnet that rides against the inside of the brake drum. If you can see any of the interior copper wiring encased in the magnet, the magnet is worn to the point of being unserviceable and should be replaced.

Are you still using the Prodigy P3 item # 90195 you purchased awhile back?

expert reply by: Jerred H

Jerred H.

9/2/2025

Hey, did you have a chance to check the wiring on your Sierra 2500 and trailer as suggested? I'm curious to know if you were able to pinpoint the issue with the brake output circuit or if you're still experiencing the overload warning. Your experience could really help others facing similar issues.