I bought one of these trailer wiring kits from B-A to avoid having to splice directly into the wiring harness.

https://www.roverparts.com/electrica...ng-kits/9439C/

Unfortunately, it is not working with my trailer, which has LED lights.

The kit puts out voltage on all the pins (running, brake, turn), but only about 9V (I have 13.5V at the battery, 12.25 at the harness plug in the right rear light well).

The trailer wiring/lighting works fine with my Chevy 1500 (which is spliced directly into the rear lighting wiring).

B-A says that their harness is not designed to drive LEDs (their literature doesn't mention this limitation). As the LEDs match the impedance of resistive bulbs, and the voltage-current is DC, I don't see why LEDs would be an issue except that they won't work below a certain voltage threshold (whereas resistive bulbs will work well below 12V, just dimly).

Has anyone had experience with these 5 wire-to-4 wire "plug-and-play" trailer harness kits not putting out sufficient voltage?

Any thoughts on how to determine whether the kit really is incompatible with LEDs or whether I just have a bad kit.

Any help is much appreciated.