Where Does the Red Wire for a Brake Controller Attach to a Vehicle

Updated 08/13/2024 | Published 10/31/2013

Products Featured in This Question

Curt TriFlex NEXT Trailer Brake Controller - 1 to 4 Axles - Proportional

(815)

$124.95

Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires

(3276)

$124.38

Pollak Circuit Breaker - Cycling/Automatic Reset - 40 Amp - Straight Mount Bracket

(47)

$7.40

Hook Probe Circuit Tester

(56)

$11.94

Question:

Hi, I bought a Curt Triflex and a 4 to 7 way connector. I need to wire them manually no internal set-up for the brake box. I clipped off the connector on the end of the brake box not the way you would do it, I know, and wired the white and black wires per instructions that came with the controller. The blue wire is also understood - it connects to the blue wire on the 4-7 way connector. I am unsure what to do with the red wire. The brake lights will be activated by the existing 4-way connector, correct? I thought that I could just wrap the end of the red wire on the brake controller with electrical tape. I would also wrap the end of the yellow wire on the 4-7 way with electrical tape. Does this work? If not, please explain it to me. Thank you.

asked by: Ralph B

Expert Reply:

The red wire on a brake controller signals the controller that you are stepping on the brake pedal, so it has to be connected. It does not operate the brake lights on the trailer. It attaches to the cold side of the brake switch. The brake switch is located above the brake pedal. If I knew the year, make, and model of the vehicle I might be able to tell you which wire it is.

To find it you will need a circuit tester like # PTW2993 if you do not already have one. Use the circuit tester to probe the brake switch wires. You need the one that only shows power when the brake pedal is pressed. If it also shows power with the head lights on or turn signals engaged, it is not the correct wire.

The yellow wire on adapter # 30717 is typically used for reverse lights. If your trailer does not have reverse lights, then you can tape up this wire and stow it out of the way. The white wire must be attached to the vehicle frame. Blue is from the brake controller blue wire like you said. And black is for 12-volt power. It is supposed to connect to the positive battery terminal via a 40-amp circuit breaker # PK54540.

We actually have a whole kit for this exact purpose: adding a 7-Way and hardwiring in a brake controller. It is # ETBC7. I have included some links that will help you with this installation.

expert reply by: Michael H

Billy

8/12/2024

Thanks, I have looked and looked for the plug for plug and go but do not see even though my truck does have the trailers wires already factory installed. I just got tired of looking for it. Thanks again