Troubleshooting 4-way Flashers on Trailer

Updated 01/14/2019 | Published 01/11/2019

Products Featured in This Question

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

(401)

$50.90

Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps

(312)

$41.73

LCD Digital Circuit Tester

(26)

$26.67

Question:

Installed Curt 555513 Custom wiring and Curt 57674 Dual Output Adapter. Everything works well except I get no 4-way flashers on the trailer when they flash on the truck 2008 Toyota Tacoma Base

asked by: Ken G

Expert Reply:

Most likely the problem is a weak ground on the trailer wiring. When your hazards are on all of the trailer and vehicle turn signals will be activated at the same time so a bad ground could prevent the lights from working.

Check the condition of the grounds of each trailer light assembly and the condition of the main ground from the trailer wiring harness to the trailer frame. Make sure all grounds are made to a clean bare metal surface. Also check that the white ground wires on Curt 4-pole harness # C55513 and adapter # C57674 are similarly making solid contact to clean bare metal surfaces.

My tech contact at Curt also suggested testing the main harness # C55513 with a tester like # PTW2992 when you do NOT have the adapter in place. This 4-pole harness is the non-powered type that relies on the power delivered by the vehicle's own wiring and it may not be receiving enough to reach through the adapter and power the lights.

expert reply by: Adam R