Troubleshooting Jeep Lights After Installing Flat Tow Diode Kit

Updated 03/11/2019 | Published 03/09/2019

Question:

Motorhome towing a 2018 Jeep have installed the diodes in the Jeep but lights still not working what could cause this

asked by: Matt

Expert Reply:

The best troubleshooting step I can recommend based on the information provided is to apply a circuit tester like # PTW2992 to the wiring upstream of the diodes. In other words, you want to test to confirm that light power from the motorhome harness is entering the diodes. You do the same test on the wiring from the Jeep itself.

If you refer to the photo I linked you'll see that the diode has both a motorhome feed (yellow wire, top left) and a vehicle feed (black wire, top left). When you test the yellow wire with the Jeep connected to the motorhome harness and the motorhome lights are operating you should have a signal on the yellow wire. When you are not towing the Jeep and you simply apply the brake or turn on the headlights you should detect a signal from the Jeep itself on the black wire.

You can also refer to the two inked articles.

expert reply by: Adam R