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Trailer Wiring Harness Installation - 2000 Toyota Tacoma

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How to Install a Wiring Harness for a Trailer on a 2000 Toyota Tacoma

This part number will fit 1995-1/2 - 2004 Toyota Tacomas and 1985-1995 Toyota pickups. The first steps involved is taking off the taillight assemblies. Well put them off to the side and then run our wiring inside. We will start on the drivers side first and work our way to the passengers side. Well disconnect the taillight by unplugging this electrical plug here. We will set the taillight assembly off to the side. What were going to do now is install the left hand part of the harness. Were going to follow this harness down through the body and follow that route and we will come back with this part with the yellow wire back up the same way. We will T it off here and well make a couple more connections. Now we will take our ground wire and run it the same way, we will overlap it and ground it to this piece of steel here.

Next we take our T-connector going to our passenger side and run it straight up and follow the wire harness all the way across and run this connector up to the taillight like we did for the other side. At this point we can run up any slack we have with a zip tie. Now we can reinstall our passenger taillight. At this point we can reinstall the drivers side taillight too. Now well zip tie our converter box to place it actually fits nice in this channel box right here, well just pop it back there and zip tie it. Now well route our four pole back over the frame around the original factory harness. Then we will follow it up to right above the hitch here. We will tie it off here for right now. The rest of it well zip tie it to the harness. There you have it for our wiring install, part # 118379 on our 2000 Toyota Tacoma.

Johnny O.


We installed the harness just as it said, After installing the trailer hitch that came with it, It was very easy to install both, After the installation we plugged it into the flat plug on my trailer and it worked great, Tail lights & Brake lights worked well and so did the right & left turn signals, The very next day I hooked up the trailer for a true test run and the lights were working when I started and then the turn signals would not come on when I stopped on the side of the road to check them, After one week of trying to fix the problem thinking it was the ground I took it to the Heathcock trailer shop and they charged me $120.00 to put a ground wire on the truck side and showed me by testing before I left that all was good, So I went home and parked my truck for the night, Next morning I was excited and plugged my magnet lights in to the plug on the truck & the running lights & brake lights worked but not the turn signals, I called Heathcock and they told me it has to be in the converter, I am out of money and no turn signals now.

Etrailer Expert

Jon G.


The Tekonsha T-One # 118379 does come with a 1-year limited warranty so I'd definitely try to take advantage of that if I were you.

Info for this part was:

Employee Jeff D
Installed by:
Jeff D
Employee Joshua S
Video Edited:
Joshua S
Employee Shane T
Test Fit:
Shane T

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