Equipment Needed to Install Brake Controller on 2003 Lexus RX300

Question:

Hi, I have a 2003 Lexus RX300 with the towing package so I already have the 4 pin flat trailer connector. I would like to add a brake controller. Possibly an inertia controller. Can you tell me what exactly I need in terms of controller and any additional wiring. I would need an adapter from 4 pin flat to 6 pin round as well as the trailer has that configuration. Thanks

asked by: Mark C

Helpful Expert Reply:

I'd be happy to help you with that. Beginning with the brake controller I'd recommend going with a proportional controller like the Tekonsha Primus, part # TK90160. A proportional controller can sense how quickly the tow vehicle is braking, and will send the correct amount of voltage to the trailer brakes so the vehicle and trailer stop at the same rate. Time delayed controllers will always send the same amount of voltage to the trailer brakes (according to how you've adjusted it) whether you've tapped on the pedal or having a full out panic stop. A proportional controller provides safer, more predictable braking.

You'll also need our brake controller installation kit, part # ETBC7 which would provide the more common 7-way blade type connector or the # ETBC6 which provides a 6-pin connector. If you know for sure that the only trailer you'll ever tow is the one you currently have, then the # ETBC6 would be the way to go. If you suspect that sometime in the future you might upgrade to a different trailer, you'd be better off going with the # ETBC7 and using an adapter like # 47549, so you'll be set up with the most common trailer connector.

Both install kits install in the same manner. The 4 pole to 7-way (or 6-way) adapter plugs into the existing 4-pole leaving 3 or 4 extra wires, depending on which install kit you use. The white wire grounds to the vehicle frame, the blue and black wires connect to the brake controller power output wire and the positive battery terminal (passing through a 40 amp breaker included with the kit), respectively and the purple wire (on the 7-way kit) would connect to the reverse light circuit if the trailer had reverse lamps. If not, the wire can be bundled up out of the way.

The controller itself would mount under the dash to the right of the steering column. The controller has 4 wires exiting the rear. The black wire connects to the positive battery terminal, after running through the 30 amp breaker included with the kit. The white wire grounds to the negative battery terminal, the blue wire connects to the wire ran to the front of the vehicle that carries the brake output and the red wire connects to the brake stop lamp switch. The stop lamp switch is located atop the brake pedal. The switch can have several wires exiting it. Use the circuit tester included with the kit to test each wire. You're looking for the wire that only shows voltage with the brake pedal pressed.

All this is outlined in the FAQ articles I've linked for you and in the install video. The video shows a controller being installed in a Toyota Highlander. The procedure isn't vehicle specific except for where the red brake controller wire connects, so what's shown in the video is almost exactly what you'll do on your RX300.