Troubleshooting Trailer Turn Signals that Blink at the Same Time when attached to 1989 Toyota Pickup

Question:

I have a 1989 Toyota PU. After installing this harness and hooking it up, both LT and RT blinker lights blink together. Brakes light work OK. It did this on the original trailer lights so I replaced the trailer harness with a new one and it does the same thing. Any ideas on what the problem might be?

asked by: Duane D

Expert Reply:

We will need to isolate the problem to the vehicle or the trailer wiring. Using a circuit tester, item # PTW2993, if needed, check the vehicle side trailer connector without a trailer connected. You should get taillight on the brown wire, stop and right turn on the green wire, stop and left turn on the yellow wire and the white wire is the ground connection.

If the trailer connector at the rear of the vehicle is working properly, when there is no trailer attached, you will need to check the trailer wiring for a short or a bad ground. You may also have the tail lights wired to the same turn/stop circuit causing the issue.

If the connector on the vehicle is not working properly, with no trailer connected, then you will need to check the wires going into the converter box on the Draw-Tite T-One Wiring Harness, item # 118379. You should get tail light on the brown wire, stop light on the red wire, left turn on the yellow wire, right turn on the green wire and the white wire is the ground connection that needs to be connected to a paint, rust and corrosion free part of the vehicle frame.

If the functions going into the converter are correct and the functions going out are incorrect and the unit is grounded properly, then the converter has been shorted and will need to be replaced. I have included a couple of videos that should help with testing your wiring.

expert reply by: Robert G