Connecting the Reverse Light Circuit to a 4 to 7-Way Adapter on a 2002 Toyota Tundra

Question:

Your videos that describe converting a 4 pole harness to a 7 pole harness state that the yellow wire is to be connected to the cars back up light circuit. The back up circuit wire on my car is a fairly small diameter wire. Does this just get spliced directly onto the thicker yellow gauge wire of the 7 pole adapter? I read on a Toyota Tundra 2002website that a relay is added to this back up circuit. Can you explain the purpose of adding a relay? Is a relay needed? Do you sell such a thing?

asked by: Ray L

Expert Reply:

If the wire on the truck is too thin to attach the yellow wire from adapter # 30717 then you can tap into the reverse light circuit using a fuse tap at the front of the truck. Use the power distribution box lid or owners manual to find the reverse light circuit fuse location. You will need extra wire to run from the engine compartment to the 7-Way, # 12-1-1. Avoid areas that can pinch or burn the wire. You can use wire ties to secure the wire under the truck.

If you want to try to use the reverse light wire at the back of the truck you can use a quick splice connector, # SWC501746-1. I have linked a video to the right that should also help.

If the trailer does not have reverse lights or otherwise does not require a reverse light circuit for any purpose then it does not have to be connected.

A relay should not be required. Relays allow power to go through a circuit when told. At the reverse light wire at the back of the truck, power will already be running when the vehicle is in reverse so a relay should not be needed. Models that have a factory tow package might have one at the front of the truck but when adding a 7-Way it is not required.

expert reply by: Michael H