Troubleshooting Trailer Lights Not Working When Using 4-Way to 7-Way Adapter with a 1999 Dodge Ram

Question:

How many wires should be hot at the 4 way adapter to 7 way when applying brakes.. Im getting voltage at 2 of them. But the brake lights on trailer are not working.. Running lights work fine. Also with blinker on both taillights blink. Trailer is completely rewired and works fine on another vehicle.. Also with headlight switch on im getting power on the trailer ground side. I put the circuit tester on the trailer and it gives me voltage. Something is wired wrong on the truck just cant figure it out. The 4 way plug on side of 7 way works as it should with another trailer that only has 4 way plug. Could it be the actual 7 way adapter on truck that is causing power to go to more than 1 blade. Without trailer hooked up i only get voltage to 1 blade but if i connect trailer then headlight switch sends signal to like 4 or 5 prongs. Which i tested before the 7 way and it only give me current on the proper wires.

asked by: Guillermo R

Expert Reply:

Thank you for the detailed troubleshooting information!

Since you have new wiring on your trailer that works with another vehicle, and since the 4-Way on your 1999 Dodge Ram Pickup works with a different trailer, it sounds like the problem is your adapter.

I recommend replacing your adapter with the Hopkins # 37185. This plugs directly into the 4-Way on your pickup and provides 4-Way and 7-Way connectors for your towing applications. It comes with a mounting bracket but to keep from having to drill into your trailer hitch or bumper you can use a No-Drill Mount Bracket # 18140 for quick and easy installation.

expert reply by: Jon G