Troubleshooting No Turn or Stop Lights on Trailer with Tekonsha T-One Wiring Kit

Updated 09/26/2024 | Published 04/18/2019

Products Featured in This Question

Hook Probe Circuit Tester

(66)

$12.94

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

(225)

$82.68

Question:

I bought the T one connector the running lights work no brakes or turns

asked by: Dan G

Expert Reply:

The first thing to do is determine if the problem is on your vehicle or trailer side. Use a circuit tester like part # PTW2993 to test the 4-Way Flat T-One # 118670 that fits the 2017 Nissan Pathfinder you selected as your vehicle info. I have attached a photo showing what pins are for which functions.

Since the wiring is new I would imagine that the problem is on your trailer. When you will need to do is make sure that your trailer plug is clean and free of debris and corrosion. If this is the case then you need to check the grounds for your left turn/stop and right turn/stop circuits as well as the wiring for these as well. Be sure the grounds are connected to a clean, bare-metal surface and that your wiring doesn't have any brakes or is exposed anywhere.

If this doesn't fix your problem let me know and I can help you to troubleshoot further.

expert reply by: Jon G

click to enlarge

Michael

9/26/2024

Hi Jon - I am experiencing the same problem. It is on the vehicle side as I have tested the trailer with a separate vehicle, as well as using the circuit tester on the car side. Tail/running lights work fine but no brake lights or turn signals.

Jon G.

9/26/2024

@Michael If you have the same T-One Harness # 118670 mentioned above, then you likely have a relay go out and you'll need the Curt Relay Kit # C57000. You can verify this by swapping out the different relays you already have. Since the tail/running light function works you can use that relay to test and see if the stop/turn functions work when you're using a relay you know is good.