Troubleshooting Running Lights Not Working
I have a ford f150 2013 and the 7 pin plug works for brake lights, directionals but not the running lights. I am getting a voltage and only measuring 10.5 V at that prong. I disconnected the whip and still only 10.5 V.. The fuses and relay on the truck look good. Any idea where i am getting the .. i have 12 V at the 7 pin...... THANKS
asked by: Doug T
Helpful Expert Reply:
If the running lights are not working on your trailer when you are connected to your 2013 Ford F-150 and you are sure the fuses and relays look good there are still a few troubleshooting steps I can offer.
In order to determine the specific problem you will need to purchase a circuit tester if you do not have one - the very handy Cordless Circuit Tester # PTW2979 would be my strong recommendation due to how easy it is to use - and test the connector on your vehicle after disconnecting it from your trailer. Check the wiring going into your harness from your tail lights to see if those wires are carrying the correct signals, if not then the issue is with the vehicle wiring.
If the signals going to your harness are okay, you'll need to test the signals coming out of the harness, and if they are correct then your issue is likely going to be with the trailer side wiring. You will also want to check both your vehicle and trailer connectors for corrosion, which can be green or white in color. A build-up of corrosion can interfere with the signals getting through the connectors so if it is present you are going to need to either replace the plug or clean the corrosion. You'll also need to make sure your grounds are attached to bare metal surfaces and free of any paint, dirt or corrosion.
Finally, check your wiring thoroughly to ensure there are none that are crimped, broken or otherwise damaged. I have added links to a pair of help articles on trailer wiring, including a troubleshooting guide which I highly recommend taking a look at.
- Q&A: Testing for Proper Voltage on the Brake Output Circuit
- Article: Trailer Wiring Diagrams
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Q&A: Trailer Brakes Lock Up When Connected to Truck
- Article: Testing Trailer Brake Magnets for Proper Function
- Q&A: Trailer Lights Work But Brakes are Not Working
- Q&A: How Long Does It Take to Install B&W Turnoverball Underbed Gooseneck Trailer Hitch BWGNRK1020
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Article: Troubleshooting Brake Controller Installations
- Q&A: How Much Voltage Should Be Applied To Brakes on Trailer w/ Electric Brake Controller
- Q&A: Troubleshooting Voltage Drop to Trailer Brake Assemblies
- Q&A: How to Test Brake Controller without Trailer Connected
- Article: Wiring Trailer Lights with a 4-Way Plug (It's Easier Than You Think)
- Article: How to Install a Brake Controller on Chevrolet / GMC 1999-2006 Pickups