Troubleshooting Parking Light Running Light Issue on 2016 Ford F-350  

Question:

Expert Reply:

Using a circuit tester like # PTW2993, you will turn on your parking/running lights and then check the 11 o'clock pin at the 7-way. If you are getting signal there, then clean the connectors on both the vehicle and trailer side using some sand paper and use some dielectric grease # 11755 to prevent corrosion and debris.

If you are not getting signal there, first disconnect the factory harness behind the connector and check with circuit tester as the connector may be bad. If that checks out, make sure no pins are bent and reconnect. Next trace that running light/parking light wire using the circuit tester probing the wire every couple feet to find the short and replace the section needed with # 16-1-1.

If you have signal at your connectors and have cleaned them, next you will check your ground connections on your trailer. The first one will be near the trailer coupler and you want to make sure it is bare metal to metal and free of any corrosion or debris. Then you will want to use the circuit tester to test the parking lamp power wire at each tail light. If you have signal at each, then you will want to check the ground connections there. They also need to be bare metal to metal and clear of corrosion or debris. If you don't have a separate ground wire, then the tail lights often are grounded through the mounting hardware.

If you don't have signal at the tail lights then trace the wire probing through the insulation every few feet with your circuit tester until you find the short. Replace with # 16-1-1 as needed.

expert reply by: Jason S

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