GM Service Manual Online
For 1990-2009 cars only

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Ignition On, Engine Off

ALC Light Sensor

Exterior Lamps

Volts

0.4-4.4 volts

Battery 1

Exterior Lamps and Interior Lamps

Volts

Battery Voltage

Dome Lamp Command

Interior Lamps

On/Off

On when dome lamp requested

Dome Lamp Feedback

Interior Lamps

High/Low

Low when dome lamp requested

Driver Door Switch

Interior Lamps

High/Low

Low when driver door is open

DRL Relay Command

Exterior Lamps

On/Off

On when DRL is requested

DRL Relay Feedback

Exterior Lamps

High/Low

Low when DRL is requested

Headlamp Feedback.

Exterior Lamps

High/Low

Low when headlamps are requested

Inadvertent Power Cmd.

Interior Lamps

On/Off

On when inadvertent power is active

Inadvertent Power Feedback.

Interior Lamps

High/Low

Low when inadvertent power is active

I/P Dimmer Input

Interior Lamps

Volts

0.5-4 volts

I/P Dimmer Output

Interior Lamps

% DC

19-100%

Key In Ignition

Interior Lamps

Yes/No

Yes with key in ignition

Low Beam Input

Exterior Lamps

Volts

0.4 volts - Battery Voltage

Low Beam Input = DRL

Exterior Lamps

Yes/No

No when low beam headlamps are off

Low Beam Input = High

Exterior Lamps

Yes/No

No when low beam headlamps are requested

Low Beam Input = Off

Exterior Lamps

Yes/No

No when low beam headlamps are requested

Low Beam Switch

Exterior Lamps

On/Off

On when low beam headlamps are requested

Parklamp Cmd.

Exterior Lamps

On/Off

On when park lamps are requested

Parklamp Input

Exterior Lamps

Volts

4.8 volts - Battery Voltage

Parklamp Switch

Exterior Lamps

On/Off

On when park lamps are requested

Pass Door Switches

Interior Lamps

High/Low

Low when any passenger door is open