How to Determine if Vehicle Needs Brake Lite Relay when Flat Towing

Question:

Will I need the Brake light relay RM-88400 - sold separately ? I have a Roadmaster BrakePro Model 9300 for my 2014 Honda CR-V and I am confused as to whether I need it or not? The BrakePro owners manual state that some vehicles need it but not sure on the 2014 Honda CR-V. Also, will I need to add an additional 20 AMP Power Plug for inside the CR-V for the BrakePro connection? The 9300 owners manual indicates it must have a 20 AMP power plug connection to work. What is recommended?

asked by: William S

Expert Reply:

To determine if a brake light relay is needed to properly wire your vehicle to be towed, answer the following questions.

Are you using a supplemental braking system that depresses the brake pedal in your towed car?
No - You do not need a brake light relay.
Yes - You may need a brake light relay. Continue on to the next question.

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.

Do your towed car's brake lights act as both the brake signals and the turn signals?
No - You may need a brake light relay. Continue on to the next question.
Yes - Your towed car has a combined lighting system. You will need a brake light relay to ensure proper activation of its signal lights.

Does your towed car have separate brake lights and turn signals?
No - Your towed car has a combined lighting system. You will need a brake light relay.
Yes - Your towed car has a separate lighting system. You may need a brake light relay. Continue on to the next question.

Are you wiring your vehicle with a six-diode kit or a TowDaddy custom wiring harness?
No - You will need a brake light relay to ensure proper activation of your towed car's signal lights.
Yes - You do not need a brake light relay.

If the accessory outlet of your vehicle doesn't have an amperage rating of higher than 20 amps then you can use the part # RM-9332 which will wire directly to your vehicle battery.