2005 GMC Sierra Tailer Wiring Left Turn Signal And Left Flasher Not Working

Updated 05/05/2010 | Published 05/02/2010

Question:

My left turn signal on my trailer wiring circuit and left flasher wont work despite their working on the vehicleI have already checked the trailer wiring circuits and also checked it against several different trailers with consistent results.

asked by: Arnold

Expert Reply:

My first reaction is that there is most likely a blown trailer tow package fuse in the vehicles power distribution box under the hood. Usually there is a legend under the cover for the power distribution box that tells you where each fuse is. I would check this first. The tow package wiring protection is separate from the vehicle tail light fuses.

If the fuse is good then I would check the trailer connector at the rear of the vehicle. There is a connector at the 7-Way on the rear of the vehicle. Press the locking tab and remove the vehicle wiring from the connector. Check the connections inside the vehicle side connector and the trailer connector. You may find that corrosion has caused the problem you are seeing. Try to clean the corrosion off the affected areas or if needed you can replace the trailer connector with the Hopkins Wiring for the 2005 Pickup, Sierra by GMC, item # HM40975.

If this does not solve the issue I would break out the circuit tester, item # 3808 if needed, and start checking the wiring from the connector back along the vehicle frame until I found where the problem originates.

expert reply by: Robert G