Diagnostic Functions Additional Heater 912-B (2000-2004): Overview: Notes
The control module has a built-in diagnostic system, the Volvo on-board diagnostic (OBD) system. This system continuously monitors itself and the input and output signals.
CAUTION:
To communicate with parking heater 912B installed in cars with chassis numbers to 314999 inclusive and in cars with chassis numbers 315000 and later where the early heater unit (30863852) is installed, a special diagnostic cable
9511520
must be used. In certain cars communication with the parking heater cannot be established when the ignition is switched on because of the absence of +15 voltage supply. To communicate with this type of heater it must be started or an attempt to start it must be made using the timer. Single components and functions cannot be activated when the +15 voltage supply is absent.