Recommended Replacement 4-Way and 7-Way Wiring for a 2003 Toyota Tundra Without a Tow Package

Published 09/15/2010

Products Featured in This Question

Adapter 4-Pole to 7-Pole and 4-Pole

(663)

$31.52

Curt Powered Tail Light Converter with 4-Pole Flat Trailer Connector

(1704)

$80.33

Question:

I have a 03 tundra 4x4 without the tow package. I do have a connector inside the the panel on the drivers side. In 2004, I had a shop put a hitch on since they were the only ones that sold a hitch for my truck back then They also wired it using parts from 4 or 5 packages. Needless to say it was band aided together. I was rear ended and it tor up the plug in under the bumper. I want to replace it so I need the hardware and wiring for the flat and the round connectors. Can you help me??

asked by: Bob

Expert Reply:

The # 20137 would not be a fit for your 2003 Toyota Tundra, as it will only work on models with the factory tow package.

In order to first replace the 4-Way plug, you will need to use a hardwire kit, like part # C59236.

The # C59236 wiring kit is a universal application, so vehicle specific instructions are not available for your Tundra. You will need to use the included circuit tester to determine which wires behind your vehicle taillights are performing which function, and connect the wires from the converter accordingly.

First, you will need to access the back side of your tail light assemblies, where the wires going to the signal bulbs are coming out. Then you would have a friend sit in the cab and activate the turn signals and press the brake pedal while you are testing the wires in the rear of the vehicle. For example, if your friend flips the right turn signal and you are testing a wire on your right tail light that flashes when the signal is applied, this would be your turn signal wire.

You would connect the wires from the converter as follows:
White: Ground wire, connected to a suitable grounding location on the vehicle frame.
Green: Right turn.
Yellow: Left turn.
Brown: Tail light.
Thin Red: Brake light. This wire is only used if your truck has separate, amber-colored turn lights. If not, it can just be tied up.
Thick Red: Power lead wire, run to the vehicle positive battery terminal, with the included fuse and fuse holder in between.

To convert the 4-Way to a 7-Way plug, you would use adapter # 37185. To install the adapter, you would first plug it into your 4-Way connector. Then, you would connect the additional wires as follows.

White: Ground wire, connected to a suitable metal grounding point on the vehicle frame.
Blue: Electric brake wire, connected to the electric brake wire coming from the back side of an electric brake controller, if present.
Black: 12v power wire, connected to the vehicle positive battery terminal with a 40amp circuit breaker, part # 9510 if needed.
Yellow: Reverse light wire, connected to the vehicle reverse light wire behind the tail light assembly, if needed to power reverse lights on the trailer. This wire can also be used to power a reverse lockout function, or as an auxiliary 12v power source. Alternatively, it can be tied up if not needed.