Troubleshooting a Replacement Ford Tow Package Wiring Harness for No Left Turn Signal

Published 09/27/2012

Question:

I installed the 7-way harness on my 2002 F150. There is power coming out of the 7-way connector for the running lights, brake lights, right turn signal, electric brakes and back-up lights, but no power to the left turn signal. All of the lights and signals work on the truck, it is only the one circuit on the 7-way connector with a problem. How can the vehicles lights continue to work and not the 7-way? Thanks,

asked by: Ed Q

Expert Reply:

I would try unplugging the harnesses and relays and then plugging them back in as it sounds like the left turn signal circuit is not making contact somewhere and it could be as simple as reconnecting the harness to fix the problem.

Next. I would check the vehicle side plug that the Tow Ready Custom Fit Vehicle Wiring # # 118242, plugs into. If this circuit is functioning properly then check the wires coming out of the new connector to determine if the power is getting to the 7-Way harness. If not there is most likely a problem with the connection.

Basically, you will just need to test the circuits until you find where the left turn signal is working and then trace it back while continuing to check for voltage until you find the signal stops and that is where the problem is and you will need to fix what you find as necessary.

If voltage appears to be going into the harness correctly but not out of it then the problem might be the harness.

On the 1997-2004 models there is also an additional fuse block on the firewall that houses the right/left tow package fuses. You may check there also.

expert reply by: Jameson C