Adding a 4- to 5-Way Adapter on a 2015 Toyota Highlander

Question:

I have a 2015 Highlander with a 4-pin harness installed purchased from Etrailer. The new trailer I just purchased has a 5-pin connector for a solenoid release on the trailers hydraulic brakes. Is there a 5-pin or 7-pin connector for the Highlander that will work to replace the existing 4-pin and give me the reverse light functionality, or do I need to splice into the reverse lights wire somewhere in the vehicle? If I need to splice, where do you recommend I do this - the reverse lights are on the rear door and route through the top of the door into the ceiling of the vehicle.

asked by: Tim P

Expert Reply:

What you will need is a 4-Way to 5-Way adapter, # 20036. You will have to splice into the reverse light wire to install the 5th wire (blue). You mentioned that the wires go from the rear hatch into the roof of the vehicle. If you pull or cut back the covering on those wires to reveal the actual wires you can use a circuit tester such as # PTW2993 to test them to find the reverse light wire.

What you will need to do is chock the vehicle wheels, apply the emergency brake, and start the motor. Have someone shift into reverse while holding their foot on the regular brake. So basically, all this is to keep the vehicle from moving while in gear. Then you will test the wires until you find the one that has power with the reverse lights on (you will need to have the person shift in and out of reverse to make sure you have the right wire).

Then it is just a matter of splicing in the blue wire and routing it however you can down to the 4-Way.

expert reply by: Michael H