7-Way and Brake Controller Recommendation for 2004 Lexus RX 330

Updated 05/30/2025 | Published 03/29/2017

Products Featured in This Question

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

(3433)

$117.85

Question:

Hi, I have a 2004 RX330 and will be installing a hitch and 7 pin connector/harness to prepare to tow a light-weight travel trailer with electric brakes. Can you direct me to the p/n for the harness which includes a 7 pin connector, rather than the standard electrical 4 pin connector? Thanks,

asked by: Eric

Expert Reply:

You will need to start with a 4-way (if you do not have one). For that you would want the # 118478.

From there you would need to convert the 4-way to a 7-way so that you can install the brake controller. For that you will want the Brake Controller Install Kit and 7-Way Adapter part # ETBC7. I attached installation instructions and an install video for this product as well.

For a brake controller I would recommend the Prodigy P2 Brake Controller part # 90885. This is our best selling brake controller because of how well it works and how easy it is to setup.

expert reply by: Jameson C

Dustin

5/29/2025

Hello, I have a 2004 Lexus RX330. When installing the brake controller part #90885 can I extend the red wire from the back of the brake controller to the rear of the car and splice it into the red wire that that plugs into the passenger side of the tail lights from the 4 way flat wiring harness part # 118478? Will that work as a source for the brake signal for the controller? Thanks

Jameson C.

5/29/2025

@Dustin the reason you can't do that is that the blinker activates that circuit too so you'd get pulsing trailer brakes when the blinker is on. It has to be a dedicated stoplight circuit.

Dustin

5/29/2025

@JamesonC That makes sense. What wire on the lexus is the correct one to splice into? Thanks

Jameson C.

5/30/2025

@Dustin Normally it's found at the brake pedal switch. You'd want to test all of the wires that run to the brake pedal till you find one that has 12 volts only when the brakes are applied and use it. Sometimes people will use the third brake light circuit at the rear of the vehicle but that's pretty rare since you have to run wire all the way to the rear of the vehicle.