Troubleshooting A Hopkins Plug-In Tow Bar Wiring Kit In A 2018 Ford F-150

Updated 02/01/2023 | Published 01/31/2023

Products Featured in This Question

Hopkins Custom Tail Light Wiring Kit for Towed Vehicles

(125)

$81.07

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

(3187)

$175.27

Question:

I installed the Hopkins Custom Tail Light Wiring Kit for Towed Vehicles Item # HM56009 on my 2018 F150 to tow behind my motor home. When I hook up the truck and test the lights my driver side upper tail light and brake light work and passenger side lower tail light and brake light work. The whole tail light does not work on either side, any suggestions on what to look for ?

asked by: Kurt S

Helpful Expert Reply:

Since you bought a plug-in kit there's only one way for it to plug into your F-150's wiring tail light wiring harness so we know there's no chance for user error other than just not plugging the connectors fully in. I recommend pulling them back apart and checking the prongs of the connector to rule out debris blocking the connection.

Double-check that your ground is mounted directly to frame of the vehicle, as a bad ground can also cause all kinds of wacky behavior. Other than that this wiring harness is a closed system and doesn't allow for modification or repair so you'd unfortunately be looking at replacing the entire wiring harness. Most likely the control module is malfunctioning and incorrectly sending signals but there's nothing that can be done to fix it.

I typically try to persuade people from purchasing any plug-in kits for this reason since they don't give you the option to make repairs and have a high fail rate. My honest recommendation is to return the wiring harness if you're still within warranty and go with a splice-in diode wiring kit to avoid these issues. I recommend the Roadmaster Diode 7-Wire to 6-Wire Flexo-Coil Wiring Kit # RM-15267.

Splicing into the wiring can be scary but it's honestly a lot easier than you'd think. I've attached a short video below where Shane will walk you through the installation process if you choose to go this route.

expert reply by: Kevin C