What Installation Process Is Needed For A Roadmaster Brake-Lite Relay Kit In A 2020 Ford F-150 4WD

Published 10/01/2021

Question:

My F150 has a key, not push button. I purchased the Roadmaster Brake Relay kit but am unsure whether to use directs A cut blue wire or B. The F150 does not have a Neutral Tow Kit which by definition is only for ford explorers and rangers, but does have neutral tow procedure built in. Several forums have stated using directions A will cause shift problems. So what do I use as the directions simply dont match a kit you listed as 100 compatible with 2020 F150 4WD

asked by: Richard

Expert Reply:

Since your 2020 Ford F-150 does not have a push-button ignition or Neutral Tow Kit then you will want to follow instruction sheet A for installing the Roadmaster Brake-Lite Relay Kit for Towed Vehicles # RM-88400. I looked through a few forums and in each one the issue with shifting out of park afterwards was caused by user-error during installation.

You'll need to following the steps listed below:

1. Remove the blue wire from the kit. This wire is not needed for normally open applications.
2. Locate the brake-light-switch wire in your towed car. This wire is purple/white for your vehicle.
3. Remove the brake light fuse.
4. Cut the brake light wire a few inches away from the "cold" side of the brake light switch.
5. Attach the relay to the wiring for the RV braking monitor. The diagram below shows where the green wire attaches the relay to either a Roadmaster Even Brake or BrakeMaster system.
6. Connect the black wire of the relay to the brake light wire near the brake light itself using the included blue butt connector.
7. Identify a fuse that is only powered when the ignition is in the "run" position and not when it is in the "tow" position. 8.Pull the fuse. Insert the fuse into the slot closest to the fuse blades, then insert the fuse tap into the empty slot in the fuse panel.
9. Using the attached blue butt connector, connect the red wire from the brake relay to the wire from the fuse tap.
10. Ground the white wire to your towed vehicle's frame.
11. Secure the relay with the included wire ties.