This issue seems to come up a bit as most Auto 850r are this setup
OBD2 readers do not fully work on the motronic 4.3 cars.
So a dongle is useless. It may connect but not to the ECU
This method below works for the
Engine ECU pin3
Cruse control pin 13
Climate control pin 6
You must pull the codes in a way similar to the older systems. But you need some bits to do it.
https://volvoclub.org.uk/tech/service/850/TroubleshootingWithCodes-Turbo.pdf
go to jaycar and buy a 12volt LED the ones with fly wires on them..
Now in the car at the OBD2 port
You put the positive leg of the LED to pin 16. And the negative leg to pin 3.
Now create a switch between pin 4 and pin 3 a paper clip will be fine.
Or while at jaycar get a momentary action switch you will need to put some wires on it
Use the above PDF to find your error codes and how to use the other functions.