The solution for W221 Command and Seat Control Not Working
Car model and year: Mercedes W221 2008 with 85000 miles
Symptom:
Command screen didn’t turn on and all seat controls including the heating and ventilation didn’t work. and the weather has been rather cold at night, low 50s, and I don’t know if this has to do with battery when it’s cold.
I’ve checked all corresponding fuses for the command and seat control, but they are all fine.
All the other electronic controls are working normal. Also, whenever I start the car and turn it off, I get thee clicking sounds from the back near the fuse box.
Where should I start for further diagnosis without Star /Xentry?
I would start by finding a shop that does have XENTRY/DAS. I wouldn’t want to try troubleshooting one of these cars without it. I love my S-class, but I consider a collection of tools — including a laptop with DAS and adapter hardware (sd connect c4) — to be part of the cost of ownership. If you don’t want to do that, then you’ll need to find a place that does have the tools where you can take it to have troubleshooting and repairs done. While there are mechanical parts to them, they’re also rolling computer networks — and very complex ones at that. A laptop with the M-B diagnostic software is just as essential to fixing one of these as having the right sockets and Torx wrenches.
And yes the cold will cause battery voltage issues, and heat will kill it… Check voltage after sitting overnight. Then swap with the G500 if it shows low volts.