270cdi ML Both heated seats not working

[merridianmel]

Hi all, hoping for some guidance here.
I have a 2002 , 270 cdi ML, both the front heated seats have not worked whilst i have owned it. Both buttons for the seats light up solid when selected (not flashing), and i can hear the relays under the seats clicking when i operate the buttons. I have checked F8 under the bonnet (20A), and this is ok. I have swopped out K1 relay (seat comfort), behind the footwell kick panel, and physically checked connections under the seat.
I have seen mentioned before on the forum that the seat are controlled by a body control module, can someone explain how this works, and how i can test it, and where it lives on a R/H drive ML. Can this module be forced to operate the seats ?

Any help is appreciated.

 

[Doodle]

Have you checked continuity through the heating element?

 

[merridianmel]

Hi, just found detail off the internet for the plugs (X54/9+10) and what resistance the elements should be (5-10 Ohm), so will be checking these at the weekend. Be surprised if both seats, have gone though.
Interested in idea that regardless of supply, the seat heating will not turn on if body control module does not give command, trying to get clarification on this.