Troubleshooting Running Lights Not Working on 2007 Coleman Fleetwood Cobalt

Question:

I just bought a 2007 Coleman Fleetwood Cobalt. I had to get an adapter to go from the cars flat 4-way to the campers 7-way. It took a while to find the right grounding spot for that adapter, but now it is grounded to the car. Initially, one tail light didn't work at all and the other worked with the blinker and brake light but not regular lights. I replaced both bulbs #1157 and now both have the blinker and brake light but not the regular lights for nighttime driving. For what its worth, my car is a 2009 Forester and the trailer hitch and electrical connection were just installed recently.

asked by: Bob D

Helpful Expert Reply:

In order to determine the problem, you'll need to use a circuit tester such as # PTW2993 to test the connector on your vehicle after disconnecting it from your trailer. Check the wiring going into your harness from your taillights to see if those are correct, 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.

Another issue you will want to take a look at are the ground connections, as they can be the cause of numerous lighting problems. You'll want to make sure your grounds are securely attached to bare metal surfaces free of any paint, dirt or corrosion of any kind. Also check your wiring thoroughly to ensure there are none that are crimped, broken or otherwise damaged. I've added links to a pair of help articles on trailer wiring that you may also find useful.

expert reply by: Kyle S