I did this same procedure before finding your video. I used the same 14mm Hex that I knocked out of the socket holder & used the same 14mm ratch wrench. Good job. I used a homemade vacuum pump to suck out the old fluid & a simple hand pump to install the new fluid. I wished I had found your video before hand to verify it could be done without removing the cross support.
The ATC boxes don't like when your tires are worn differently, that causes the system to see slip and works the actuator harder, if the actuator has an unusual duty cycle, it throws a code.
Same TF870 specification oil used in all ATC boxes be it a bmw, a hyundai, a kia, a Landrover,a Porsche cayenne, VW toureg etc, same boxes made for many manufacturers, some manufacturers wanted a drain, some didn't, some wanted a DTC logic, some did not. Good idea using the brake pipe, beats having to remove the box
