Flat Towing Lighting Harness Recommendation for 2015 Ford F-150

Published 11/16/2017

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)

$175.28

Roadmaster 4-Diode Universal Wiring Kit for Towed Vehicles - 4-Way Flat Connectors

(3187)

$100.94

Question:

Im considering the RM-154 wiring. Im a bit confused if I need a brake light relay and how it is installed??

asked by: Jim H

Expert Reply:

The wiring is different on vehicles that have trailer wiring and ones that do not come with it at all. We see this on other vehicles that will have connections made under the hood and pre-wiring ran to back of some vehicles and on others all of that isn't there at all. In your situation there is a different style of connector than what the part # HM56009 is compatible with. Your truck has a standard round connector since you have the tow package with a factory 7-way.

For lighting you can use the diode kit, # RM-15267, and not have to worry about cutting into the taillight housing. This will splice into your taillight wiring to allow your tow vehicle to control the taillight assemblies of the towed vehicle. This comes with a round 6-way connector that you will install on the front of your towed vehicle and enough coiled wire to go from there to the RV.

expert reply by: Jameson C

Jim H.

11/16/2017

Im considering the RM-154 wiring. Im a bit confused if I need a brake light relay and how it is installed??

Jameson C.

11/16/2017

Because this harness # RM-154 wires your vehicle as a combined system, a brake light relay (RM-88400 - sold separately) may be required if you use a supplemental braking system with your towing setup. A supplemental braking system depresses the brake pedal in your towed car every time you apply the brakes in your RV. So, if your towed car's brake lights illuminate when the brake pedal is pressed and the engine is off - as is the case when towing - then you need to install a relay to ensure that the lights on your towed car always act in accordance with the signals sent by your RV via the wiring harness. Without a relay, the brake signal from your towed car will override the turn signal sent by your RV when you slow down to make turns, creating a potential hazard. What type of braking system do you have?