Do I Need a Brake-Lite Relay Kit When Flat Towing a 2025 Ford Ranger?
Updated 12/08/2025 | Published 11/17/2025
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Question:
guys I,m working with the Roadmaster Nighthawk and Blue Ox Patriot system that you recommended for my 2025 Ranger. Trying to use the Curt 58979 harness from my 2024 F-150 that was listed okay for the 2025 Ranger. Checked and re-checked all the connections multiple times. From the RV the park circuit turns on the right Ranger parking light, but its as bright as the normal brake light. The left doesnt come on. Instead, it turns on the SIDE MARKER. RV does use the TURN signal lamps on the truck for turn signals. The brake lights do activate the left normally, but the right is still at the high intensity. What do you suggest? Will the brake relay kit fix this ?
asked by: Richard
Expert Reply:
Hey Richard. Yes, the Roadmaster Brake-Lite Relay Kit for Towed Vehicles item # RM-88400 is exactly what you need to get the lights on your 2025 Ford Ranger synched up with the functions on your RV.
I've linked an installation video below along with a schematic so you can see how to get the Roadmaster item # RM-88400 installed.
(click to enlarge)
Product Page this Question was Asked From
Curt Universal Tail Light Wiring Kit for Towed Vehicles - 4-Way Flat Connectors
- Flat Tow Wiring Harness
- Splices into Vehicle Wiring
- Wiring Harness
- Universal Fit
- 4 Flat
- CURT
more information >
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on Flat Tow Wiring Harness
Jerred H.
12/8/2025
Hey Richard, how did things go after adding the Roadmaster brake relay kit to your Ranger setup? Did it get the lights working evenly with your RV signals? Your update could make it easier for others using the same wiring combo.