GM Service Manual Online
For 1990-2009 cars only

Body Control Module (BCM)

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Ignition ON/Engine OFF/Vehicle in PARK/Park Brake Released/Headlamps in AUTO/All Doors Closed

Battery Voltage Signal

Data

Volts

Varies

Ambient Light Sensor

Data

Volts

1.75 Volts Maximum Light to 4.9 Volts Maximum Dark

Dimming Potentiometer

Data

Volts

Varies

Ignition Off/Run/Crank

Inputs

Active/Inactive

Active

Ignition 1 Run/Crank

Inputs

Active/Inactive

Active

Driver Door Ajar Sw.

Inputs

Door Closed/Door Ajar

Door Closed

Passenger Door Ajar Sw.

Inputs

Door Closed/Door Ajar

Door Closed

High Beam Select Switch

Inputs

Active/Inactive

Inactive

Headlamp On Switch

Inputs

Active/Inactive

Inactive

Headlamp Off Switch

Inputs

Active/Inactive

Inactive

Front Fog Lamp Switch

Inputs

Active/Inactive

Inactive

Courtesy Lamp Switch

Inputs

Active/Inactive

Inactive

Dome Lamp Override Switch

Inputs

On/Off

Off

Cargo Lamp Switch

Inputs

Active/Inactive

Inactive

Hazard Lamp Switch

Inputs

Active/Inactive

Inactive

Park Lamp Switch

Inputs

On/Off

Off

Park Brake Switch

Inputs

Released/Applied

Released

Front Wipers Active

Inputs

Yes/No

No

Inadvertent Power Cmd.

Outputs

On/Off

On

LF Turn/Hazard Lamp Command

Outputs

On/Off

Off

LR Turn/Hazard Lamp Command

Outputs

On/Off

Off

RF Turn/Hazard Lamp Command

Outputs

On/Off

Off

RR Turn/Hazard Lamp Command

Outputs

On/Off

Off

DRL Status

Outputs

On/Off

Varies

Headlamp Relay

Outputs

On/Off

Varies

High Beam Relay Command

Outputs

On/Off

Off

Park Lamps Signal

Outputs

On/Off

Varies

Courtesy Lamp Output

Outputs

On/Off

Off

Fog Lamp Relay Cmd.

Outputs

On/Off

Off