Troubleshooting Curt T-Connector Wiring Not Working for 2021 Subaru WRX

Updated 04/24/2023 | Published 04/22/2023

Products Featured in This Question

Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(52)

$68.95

Curt 4-Way Flat Trailer Connector w/ 60" Harness and Wire Taps

(136)

$13.32

Question:

i got harness curt harness C56259 and it worked with my 16 wrx cvt, 19 wrx 5spd and 20 sti 6spd.. but i can get it to work on my 21 wrx cvt.. tried switching sides and tried different trailers.. one side will blink, the other side is dim and when i hit the brakes one side goes out.. its all plug and play except the power and it has the proper ground.. any clue what im doing wrong or does it not work for this. the C56259 is listed for the 21 wrx cvt so im lost.. thank you very much in advance

asked by: George

Expert Reply:

The Curt T-Connector Vehicle Wiring Harness # C56259 is designed to work with your 2021 Subaru WRX, but if you've had it that long and reinstalled it that many times I wonder if the wiring is just worn out. Here's what I recommend doing to determine if the issue is compatibility or just the wiring itself:

Connect all of the wiring as the instructions call for it, and then use a circuit tester to see if the correct signals are on the correct wires prior to the converter box. Then do the same on the wiring coming out of the box. If everything looks good before going into the box but looks bad coming out, then the box is bad and your wiring needs to be replaced. If everything looks good coming out of of the box but the 4-Way signals are all messed up then the end of the wiring is somehow messed up and you need to replace it with something like the Curt # C58044.

expert reply by: Jon G