I agree, there must be something wrong in the hubs for it to act like this. With a factory controller you are set up good.
Chris
i was surprised to find out that my 2014 E350 did not have the option for a factory controller. kinda disapointed me!
to the OP.. for the heck of it. maount an aux ground wire via jump cables and see if it changes anything.. IE. ground truck to traielr.
I'm surprised. The F series trucks have had them as an option since 2005. You would think the E series would also.
Chris
I know, and they aren't even retrofittable, no place in the dad for the factory controller. I'll of course add my own, but id have paid the upgrade $ for the factory one.