Troubleshooting Brake Controller with OL Code when Brakes are Applied

Question

Question:

When applying controller signals OL

asked by: Frederick L

0

Expert Reply:

If you check out the attached instructions for the Curt TriFlex Trailer Brake Controller # C24VV you can see that the OL code you are getting means that there is an "Overloaded output circuit, trailer brake system fault".

Whichever controller you have the problem and solution is the same. You have a short on your brake signal circuit from your brake controller to your trailer brakes which is causing too much power draw.

Check both the tow vehicle and trailer connectors and make sure they are clean and free of corrosion and debris. If they look good move on to the actual wiring and grounds for the brake circuit and your brake magnets. Make sure the wiring is undamaged and your grounds are securely connected to a clean, bare-metal surface. When you fix this it will fix your code.

expert reply by: Jon G

0

click to enlarge

Dave P.

4/27/2024

I get OL signal without a trailer hooked up. Any comments?

Jon G.

4/29/2024

@DaveP It means you have a short on that blue output wire from the brake controller and it could exist all the way back to the 7-Way pin on your vehicle. Trace that wire and look at all of the connections and pins for that circuit - be sure to fix anything that looks out of place.

Scott

4/28/2025

@JonG We were towing down a mountain and I was applying manual trailer brake input with this unit, when all of a sudden it said OL and has ever since. Even without the trailer attached. Why would it be working (for over a year) then suddenly do that? What all should I check?

Jon G.

4/28/2025

@Scott You'll want to trace the wire I referenced above.

Answer 1

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Answer 2

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Answer 3

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Answer 4

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Answer 5

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Answer 6

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Answer 7

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Answer 8

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Answer 9

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Answer 10

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Answer 11

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Answer 12

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