Troubleshooting Dim Lights When Using Hopkins HM56200 Flat Tow Wiring Kit
Updated 09/02/2025 | Published 08/06/2025
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Question:
I have a 2001 Ford E450 with a 7 round trailer plug. The wiring for the trailer plug is connected to the factory trailer/towing harness. We have towed a car trailer LED taillights and a tow dolly LED taillights and the trailer lights are bright. Recently we began flat towing a 2017 Jeep Wrangler. When connecting the Jeep harness Hopkins HM56200 to the E450, the taillights marker/stop/turn get dim, and the Jeep taillights are dim marker/stop/turn. Do you have any troubleshooting tips for this issue? Thank you.
asked by: Steve H
Expert Reply:
Hello Steve, thanks for reaching out. This sounds like a problem with the Hopkins # HM56200 wiring kit. These custom fit flat tow harnesses are notorious for being unreliable, and ESPECIALLY the Hopkins brand.
The first thing I would do is check the plugs on both sides and make sure they are all fully seated. Next make sure the ground wire is connected to bare metal with no paint, or rust. If all of that is good, I suspect an issue with the module itself. In that case you will want to take a wire tester and check the input and output wires on the module. If the input is normal, but the output is inconsistent, this means the module is bad which is not unheard of. In this case it will need to be replaced.
The Roadmaster # RM-15267 would be a much more reliable wiring solution.
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Jesse M.
9/2/2025
Hey Steve, did you have a chance to test the Hopkins wiring kit as I suggested? I'm curious if switching to the Roadmaster kit helped resolve the dim light issue with your Jeep. Your experience could really help others facing similar problems.