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Troubleshooting O.L Code On Curt TriFlex Trailer Brake Controller C51140


I have a curt triflex trailer brake that was working great for a while and now all it does is flash the code O.L. I have tried trouble shooting it and I cant seem to figure it out. What does this code mean and how do I fix it?


Expert Reply:

The O.L code you are seeing on your Curt TriFlex Trailer Brake Controller # C51140 means that there is a short in the trailer brake output circuit.

If you unplug the trailer from your tow vehicle, does the O.L code go away? If so that means the short is on the trailer side and you will need to check the wiring going from the 7-way connector to the braking assemblies for any damage and replace the damaged sections with # 10-1-1 and heat shrink butt connectors # DW05745-5.

If the O.L code is still there after unplugging the trailer connector that means the short is between the vehicle 7-way connector and the trailer brake controller, or the controller has an internal short. You can test this by cutting the blue wire coming from the controller at least 6" back. If the code goes away the wire coming from the 7-way connector has a short and needs to be fixed. If the code does not go away there is an internal short and you will need to replace the controller.

I included a video of the # C51140 for you to take a look at.

expert reply by:
Samuel C

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