2007 express electric brakes engaging when headlights on
 

Electric brakes work great until you turn lights on. It looks like some power back feeding to controller. Any ideas or better way to get trigger off stop light switch.

Bad grounds can cause weird stuff like that......

+1
with the trailer not connected, check for power at the trailer plug. turn the lights on and make sure the ebrake pin is not energized. this way you know the fault is with the trailer not the van.