Troubleshooting Trailer Turn Signals Not Working Curt Trailer Wiring Harness

Updated 04/25/2023 | Published 04/24/2023

Products Featured in This Question

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

(260)

$72.90

Hook Probe Circuit Tester

(66)

$14.36

Question:

I installed the curt wiring harness on my 2016 Ford transit 350. Not too difficult but the signals wont work. Trailer lights come on when van lights are on but no blinkers. Any ideas what would be the cause?

asked by: Matt G

Expert Reply:

Is the issue possibly on the trailer's wiring? Use a circuit tester like the # PTW2993 to test the pins of the 4-way for voltage and see if the trailer wiring or the vehicle wiring is the problem. Sometimes it's just a weak ground on the trailer wiring which you can improve by checking the main ground wire connection from the 4-way to the trailer frame. Sometimes it's just that the connectors of the trailer wiring need to be unplugged and plugged back in.

expert reply by: Jameson C