Troubleshooting Running Light Circuit on 7-Way of 2011 Ford F-150

Question:

my 2011 f150 has no running lights coming out of my 7 pin i checked the fuses none were blown any thing else I can check?

asked by: Bill

Expert Reply:

If you have tested the 7-way on your F-150 with a circuit tester like # PTW2993 (please see the demo video linked for you) and have confirmed that when your headlights are on there is still no signal at the pin at the 11-o-clock position (highlighted for you in the linked photo) then there are several steps, you can take to troubleshoot.

Since you already checked your fuses and found them to be okay, the first thing to check is the ground wire for the harness. This must be tightly attached to a clean bare metal surface on the truck's frame. You can remove this wire and clean/sand the surface on the frame to remove any grease, dirt, rust or primer. You need bare metal to bare metal contact on the ground's ring terminal. You can also drill a new hole for the ground terminal if that is easier. A weak ground can cause the issue you're having, allowing some functions to operate while one other does not work. Running lights, which stay on at all times, will draw more current than a turn or brake light that are only on briefly. A weak ground problem is likely to show up on this circuit.

If that does not correct the problem then test the connector that plugs in to your 7-way. This round connector's contacts can be tested in the same way as the 7-way was tested. Ground the tester and apply the probe to the contact for the running light circuit. If you have a signal here when the headlights are turned on then you know the issue is downstream of it and could be due to corrosion or a bent contact in the 7-way. Check all contact surfaces for any visible discoloration. Even slight greenish or whitish discoloration on the metal contacts can indicate corrosion that could interfere with signal transmission. You can try a spray-on contact cleaner like Caig De-Oxit.

You can also follow the running light circuit's wire from the 7-way up as far forward as you can. Look for cracks or worn spots in the wire's insulation, especially around points where it may have to make sharp bends or where it could be coming into contact with the truck frame. These conditions could cause a short. Repair any damaged wire as needed.

You can also test the trailer's running lights by disconnecting it from the truck and applying 12V power input directly to that circuit on the trailer plug. You can use the truck's battery or a spare 12V power source. If your running lights work when tested in this way, then you know the issue is upstream in the truck socket or elsewhere on the vehicle. If you do not have running lights when you apply power directly then you need to check/repair the ground wire and also the wire for the running light circuit in the same way as described above.

expert reply by: Adam R