2001 E53 - Trailer Stability Retrofit
 

Hi guys, I have an X5 E53 with a production date of 11th of February 2001.
I have fitted an OEM hitch kit I bought from ECS tuning. All BMW wiring and trainer module included and fitted :)
I have noticed while retrofitting a ULF and doing other coding in DIS/GT1 that there is a 'Trailer Stability Retrofit'!
Does anyone know anything about this 'retrofit'?
Is it just a software update that enables the function? Is there a sensor or module that I need to buy to utilise this feature. I tow race cars so I want every bit of safety the X5 can offer me :) Especially since I have been through a near death crash that wrote off 3 vehicles!