FWD only 2005. AWD fault

[B19eed]

I have a 2005 D5 XC90 with no AWD. I get the Anti-skid service required constantly. Had no idea what that meant until I tried to drive on wet grass!
It has no drive at all to the rear wheels, and by extension I assume the DTSC doesn’t function as it also appears to not have traction control.

Following the advice on many of these threads - I have tested whether the propshaft can be turned with the wheels on the ground and it cannot, so basically ruled out (the most common) mechanical issue. Had the fault codes read with a Snap-On Modis Ultra, and came up with this collection of codes:

0094 communication between control modules, communication problems with active on demand couplings.

0109 communication between control modules, communication problems with steering wheel angle sensor, internal fault.

1464 communication with the differential electronics module (dem)

0016 control module communication fault

Where do I start???