Trailer Lights not Working When Connected to Truck

Question:

I have a 2017 Dodge Ram Sport when i hook up the trailor i have no lights on the trailor I checked the ground its not that. I even moved the tounge around on the ball still got nothing. I hooked the trailor up to and older truck lights worked with no issues. I then hooked up to a 2015 RAM had the same issue no lights on trailor. When i finally gave up and moved the trailor with the 2017 Ram as soon as i put it into Gear and moved the lights came on. Any Idea?

asked by: Brian

Expert Reply:

In order to determine the specific problem, you will need to use a circuit tester such as # PTW2993 to test the connector on your Ram after disconnecting it from your trailer. Check the wiring going into your harness from your taillights 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 will need to either replace the plug or clean the corrosion and be sure to use Dielectric Grease # LT37534 to help stop any future corrosion.

I know you said you checked your ground connections, but they can be the cause of numerous lighting problems so I strongly urge you to check again. 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