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What is the wiring harness centered under the rear bumper

2100 Views 3 Replies 2 Participants Last post by  burned300
I am trying to replace the trailer wiring on my 2001 tundra TRD. The kit I got plugs into a wiring harness on the drivers side. The old 4 pin has been wired to the harness in the center of the bumper though. Trying to figure out what that harness is for and if I need to reconnect it when pulling out the old wire job. Thanks!
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Pictures? did you buy factory toyota harness?
Pictures? did you buy factory toyota harness?
It is not a factory Toyota harness. It is a curt custom wiring harness 55378. I purchased it from They have a good video showing how to install on a 2001 tundra. It plugs in on the drivers side under rear bumper. I connected it as shown in video and disconnected the center wiring plug. Truck won't start, with a volt meter on the battery while connected you can watch it drain.The first photo is the wiring harness in the center of the bundle that the old 4 pin was wired to. The right side is what is still there, the left side is what I removed. The second photo is the harness that I attached the new wiring to. It fit no problem. You can see the connected pieces on the right and the now exposed connection on the left. If you follow the wiring from the exposed bit on the left it goes to a towing convertor behind the tail light. That is what is shown in the 3rd photo. Thanks!
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