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Installing Yellow Wire of Curt C57674 Adapter for Trailer Reverse Lockout on Surge Coupler


I have a 2021 Toyota highlander platinum with the trailer pkg and a 4 pin plug in. I have a boat with surge brakes so need to find the reverse wire. Where is it located , how do i get to t and what color is it?


Expert Reply:

The reverse lamps for the 2021 Toyota Highlander are in the liftgate, so the best bet would be to find the harness feeding the taillights and use a circuit tester like # PTW2993. Unfortunately, I don't have specifics on where the harness is located or the wire colors, but this is pretty easy to figure out. The harness typically runs behind the bulkheads in the cargo area and will usually run up to the top of the liftgate in the pillar next to it.

Once you locate the harness, the first thing you'll want to do is identify which wire carries the brake lamp. Have a helper press and hold the brake pedal while you probe the wires until you find the one that has power with the brake pedal depressed. Label that wire. Then, WITH THEIR FOOT STILL ON THE BRAKE, have the helper shift the transmission in reverse. With the transmission in reverse, you should be able to find a second wire that shows power on it, which is the wire you'd use for power the reverse lockout on your surge coupler. The yellow wire on the # C57674 adapter would be extended and tapped into the reverse lamp circuit using a quick splice connector like # SWC501746-1.

expert reply by:
Mike L

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