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Troubleshooting Brake Controller That Shows Trailer Connected Then Disconnected Messages


Recently we replaced all the Incandescent marker, brake and turning lights on a 2000 CandC horsetrailer with new leds. After we did that, every time we tow it, we got frequent trailer disconnected message, followed a few seconds later with trailer connected message. Its very annoying. Weve noticed that even after the trailer disconnected message, our trailer lights dont go out, or even dim. Everything seems to be working fine, even the trailer brakes. We thought it might be a resistance problem, so we purchased the Curt 7-Way Trailer Adapter for VW, Audi, and Porsche Towing Trailers with LED Lights, Item # C57003. However, this did not solve the problem. We do not have this problem while towing a different trailer with this truck which we also replaced all old lights with leds a few years ago. Our tow vehicle is a 2016 GMC 3500 and it has been to the dealer to rule out any truck related issues. Interestingly, we also towed the trailer with a different truck 2015 GMC 1500 with no messages. Any thoughts on how to fix this issue?


Expert Reply:

Thank you for all of the details.

So far you have done an excellent job at troubleshooting by using the Curt # C57003 and connecting your truck and trailer to another truck and another trailer.

Since this problem didn't start to occur until after you swapped the lights over to LED I believe that this is a ground issue. Start off by checking your 7-Way connectors, both on your 2016 GMC Sierra 3500 and your 2000 CandC trailer, and clean out any corrosion or debris. Next, I would go back and check the grounds for your LED lights. Be sure that they are secure and connected to a clean, bare-metal surface as even some paint can cause issues.

Let me know if this doesn't fix your problem and I can help you troubleshoot further.

expert reply by:
Jon G

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