Enable Pilot Assist while towing?

[Another XC]

I discovered that to detect a trailer it senses load on several of the lighting circuits.  Connecting just one won't work. 
LED need a load resister to be detected.  I only needed a feed for the licence plate light for a tyre carrier so bypassed the trailer module completely. 

There is a setting to disable trailer assist - you could trail this and see if stability control software is what disables the other systems.