SID Unit Power Supply

SID Unit Power Supply

Battery voltage (+30 circuit)
Current (+30 circuit) is supplied via fuse 8 (22a) to pin 5 of the SID unit connector.

Battery voltage (+15 circuit)
Current (+15 circuit) is supplied via fuse 27 (22a) to pin 25 of the SID unit connector.
The SID unit is activated by current from the +15 circuit.

Diagnostics
If no current from the +30 circuit is present, the display will not be active and diagnostic communication will not be possible
If no current from the +15 circuit is present, the display will not be active but can be turned on via the bus by switching on the radio, for example. Diagnostic communication will be possible with limited functions if the ignition key is turned to ON.
The SID unit will not generate a diagnostic trouble code if no current from either the +30 or +15 circuits is present.