Help with t6.1 tow bar wiring

[kirkm5238]

Hi can any one help with a t6.1 tow bar wiring my cousin bought a kit from tps and paid some some to install the loom they have installed it but the caravan or trailer won’t work properly it’s been coded to the van so reverse sensors cut of and a picture of a caravan comes up on the screen the company who has fitted have double checked everything and say it’s a faulty trailer control module but when I scanned no faults there when it’s plugged in the indicators work as should but when brakes r pressed the indicators light up and when side lights r on they don’t work on caravan and it kills one side of the lights on the van it’s self he’s going to book it in to vw but he’s got a holiday booked and vw haven’t got time befor he goes so just trying to help him out hopefully someone else has had this issue I’m going strip rear socket of check all pins r correct according to the instructions thanks