2014 JKU + M416 = wacky trailer lights

[goin camping]

Got 2014 Jeep jku and M 416 wired with a 7 pin female plug. Jeep has a flat four male plug. Got the adapter and hooked it up.

Tail lights, blinkers and brake lights all work until... I turn on the head lights and then everything works until I hit the blinkers. Then both trailer lights flash instead of one.

Anyone have any ideas?

 

[FredB]

Is there some kind of adapter on the M 416 that converts the lights to a 7 pin? I'm asking because I recently installed armored LED taillights and turn signals on my XJ. Everything worked normally before the installation. However, afterward both turn signals would blink whenever either side was activated. Turned out the U-Haul trailer light adapter I've had forever was the culprit.