Troubleshooting Hayes Genesis Brake Controller HA81790


My box was working fine, I parked it last night, went to church this morning, everything was fine. When I came back the truck and trailer brake lights come on and off.


Expert Reply:

If there is a problem in your Hayes Genesis trailer brake controller # HA81790 that is causing the issue with the truck and trailer brake lights it will probably still occur on the truck alone if the trailer is unplugged. I suggest disconnecting the trailer plug from the 7-way socket and then checking to see if the problem persists.

If you can borrow another trailer for testing that can help determine if the problem is on the truck or trailer side.

If the truck brake lights behave normally then the problem is probably on the trailer. The trailer plug could have trapped dirt of water, or internal corrosion, that can cause different circuits to become bridged together. For example, corrosion could cause the 12V power feed to become connected to the brake light circuit.

If the vehicle lights do not function normally then unplug the controller harness # HA81783-HBC from the port on the truck and again check to see if the lights behave properly. If they do then the unit itself may have internal damage or the wiring adapter may have a corrosion issue.

expert reply by:
Adam R

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