How To Test If A Hopkins Towed Vehicle Wiring Harness Is Faulty

Published 01/13/2024

Products Featured in This Question

Hopkins Custom Tail Light Wiring Kit for Towed Vehicles

(125)

$81.08

Roadmaster 4-Diode Universal Wiring Kit for Towed Vehicles - 7-Way to 6-Way Coiled Adapter Cord

(3183)

$179.84

Question:

I have had my hopkins wiring harness 56009 installed and working fine for 1 or so. Recently just driving my tow vehicle 2016 ford f150 lariat when i put turn signal on i get a brake light glowing and opposite side flashing. It never has done this before. If i unplug hopkins harness and plug factory wiring back together my truck operates fine. So i know its the hopkins harness. Any ideas and how to test this with a volt meter?

asked by: Doug L

Expert Reply:

It sounds to me like the converter box for your Hopkins Custom Tail Light Wiring Kit for Towed Vehicles # HM56009 is faulty and not properly sending your tail light signals through to the appropriate tail light. You can verify this by testing the wire harness on both sides of the converter box to see if the function is properly passing through the converter and then going to the correct wire.

That being said, with wire harnesses like this you can't really repair them so replacement is the unfortunately the only option. Personally, I prefer splice-in diode kits like the Roadmaster Diode 7-Wire to 6-Wire Flexo-Coil Wiring Kit # RM-15267 because with these each component is replaceable. They tend to have a lower failure rate and with everything being replaceable you're not having to rip everything out when there is an issue.

expert reply by: Kevin C