How To Install The Roadmaster Brake-Lite Relay Kit On A 2022 Jeep Wrangler Limited Sport

Updated 02/07/2025 | Published 04/18/2022

Products Featured in This Question

Roadmaster Brake-Lite Relay Kit for Towed Vehicles

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$47.75

Digital Multimeter with 42" Long Test Leads - XL LCD Display

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$40.48

Question:

It seems the 2022 Jeep Wrangler Limited Sport does not have a traditional brake light switch, how is this being installed?

asked by: David E

Expert Reply:

To install the Roadmaster Brake-Lite Relay Kit for Towed Vehicles # RM-88400 on your 2022 Jeep Wrangler Limited Sport, you will start by:

1. Start by confirming that you have the right wire, you 'll want to confirm this by using a multimeter like # PT29ZR to check the wire only has 12 volts when the brakes are pressed.

2. Then you'll continue by removing the vehicle's brake light fuse located in the fuse panel.

3. Continue by cutting the brake light wire a few inches down from the cold side of the brake light switch.

4. Using the included blue butt connector, connect the black wire from the Brake-Lite relay to the other end of the brake light wire.

5. Then, you'll want to attach this wire and the brake monitor wire from the supplemental braking system to the brake signal output.

6. Next, you'll want to identify a fuse that is only powered when the ignition key is in the RUN position, and OFF when in the TOW position, then pull that fuse.

Be sure that the certain fuse you choose is not apart of the "retained accessory power circuit"

7. Continue by inserting the fuse you just pulled into the slot closest to the fuse blades, then insert a fuse tap into the empty slot in the fuse panel .

8. With the blue butt connector, connect the red wire from the Brake-Lite Relay to the wire from the fuse tap.

9. With the attached ring terminal and included 5/16" self tapping screw, connect the white wire from the Brake-Lite
Relay to a good chassis ground. To avoid grounding problems, you'll want to attach the wire directly to the frame.

10. To finish, you'll want to secure the Brake-Lite in place using the included wire ties, re-insert the removed fuse mentioned in step 2, and insert the provided 10 amp fuse into the fuse tap.

I have included an installation video on a 2017 Jeep Wrangler Unlimited for you to check out as well.

expert reply by: Bryce D

Roadmaster Brake-Lite Relay Wiring Schematic
(click to enlarge)

Roy F.

2/5/2025

I’m trying to install the brake-lite relay, 88400, on my 2024 Jeep Gladiator Mohave. The instructions say to remove the brake light fuse from the fuse panel but I have searched and read for hours and there is no fuse labeled ‘brake light’. Do you know what number fuse it is? Also, please forgive me for my ignorance but after pulling the panel under the steering I just can’t tell which one is the brake light switch. I also have no idea what you mean by cold side. Thank you, Roy

Bryce D.

2/6/2025

@RoyF Hey Roy, for that fuse you're not going to find anything called the brake light fuse. This fuse is usually labeled as a "Stop Lamp" fuse and it's located under the hood. I'm not sure what number it is, but your owner's manual should have that info. For the cold side of the brake light switch, you'll need to find the wire that carries 12V power ONLY when you press the brake pedal and at no other time.

Roy F.

2/6/2025

@BryceD Thanks for the reply. There isn't anything labelled Stop Lamp either so I made a trip to my Jeep dealer. The Jeep dealer service guys said that the BCM controls the brake light signals and recommended pulling four fuses (F20, F26, F28 & F29). Separate but related question, do I really need the Brake-lite Relay Kit? I ask because while I was waiting for your assistance I decided to test all of the lights on the Jeep after installing the diode kit. Everything worked and I even hooked everything up, to include the Patriot Portable Proportional Braking System, and took the RV and Jeep for a drive. My wife followed in a separate vehicle. She said the turn signals worked on the Jeep when applying the brakes. In other words, nothing cancelled anything else out. So I'm wondering, do I need to even install the Brake-lite Relay Kit? I look forward to your response. -Roy

Roy F.

2/6/2025

@BryceD Disregard my last reply. Roadmaster just called me back and said the Brake-lite Relay Kit is not required on 2024 Jeep Gladiators. He said they need to get the word out. Looks like I bought the kit for nothing.

Roy F.

2/7/2025

@BryceD The roadmasterinc.com Brake-lite Relay page does say this under ‘exceptions’, “With the engine off for five minutes, step on the brakes. If the brake lights do not illuminate, you don't need a Brake-Lite Relay. (The five-minute wait is to allow time for the 'automatic shut down' feature, which is present on some newer vehicles, to kick in.” Your site for the relay kit does too, kind of. On your store front for the relay kit, under product information, you walk through a series of questions (‘Is a Relay Required’). One of which says: “Do the brake lights on your towed car illuminate while the engine is off? No - You do not need a brake light relay. Yes - You may need a brake light relay. Continue on to the next question. The test for this is to check to see by depressing the brake pedal with the vehicle off. If you do this immediately, with the door open, then the brake light will illuminate when depressing the brake leading you to believe you need the relay kit. Well, not really because the Jeep has a sleep mode (as referenced under exceptions on the roadmasterinc.com site mentioned above). In addition to my previously mentioned drive test, an easy way to verify this is to leave the window open with the door closed and wait a few minutes for the jeep to go to sleep and then engage the brake pedal with something like a broom stick handle through the open window. The brake light does not come on when applying the brake so no relay kit is required. Just passing on what I have learned…