GM Service Manual Online
For 1990-2009 cars only

Body Control Module (BCM)

Scan Tool Parameter

Additional Menu Selection(s)

Units Displayed

Typical Data Value

Ignition ON, Engine OFF

Battery Voltage Signal

HVAC/Data Display/BCM/HVAC Data

Volts

13.5 Volts

Rear Defog Relay Cmd.

HVAC/Data Display/BCM/HVAC Data

On/Off

Off

Rear Defog Switch

HVAC/Data Display/BCM/HVAC Data

On/Off

Off