GM Service Manual Online
For 1990-2009 cars only

Use the typical scan tool data values for comparison after you have completed the following steps:

    • Performed the BCM diagnostic system check
    • Verified that the on-board diagnostics function correctly without displaying any DTCs

The typical scan tool data values are an average of displayed values that are recorded from normally operating vehicles. The typical scan tool data values are intended to represent what a normally functioning system would display. The values you get may vary due to a low battery charge or other reasons. The values should be very close.

Use only the parameters that the tables list for diagnosis. If a scan tool reads another parameter, do not use the values in diagnosis. For more details on the scan tool typical data values and on the use of the scan tool for the diagnosis of BCM inputs, refer to the applicable diagnosis table. If all of the values are within the range that the table illustrates, refer to the following sections:

    • Diagnostic Aids in the applicable diagnostic trouble code (DTC) table
    •  Symptom Subsection References

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Ignition Switch in the RUN position /Vehicle in PARK /Headlamps in AUTO position

Ambient Light

Data

LIGHT / DARK

LIGHT (When the BCM is in the LIGHT state and the DRLs are ON)

DARK (auto headlamps will be ON)

Ambient Light Sensor

Data

Volts

Maximum Light = 4.7 volts

Dark to Light Transition Threshold = 2.2 volts

Light to Dark Transition Threshold = 1.3 volts

Maximum Dark = 0.2 volts

Auto Headlamps

Input 2

ACTIVE /INACTIVE

ACTIVE (When the auto headlamps are ON)

Auto Headlamps Enabled

Input 2

YES /NO

YES (When the BCM is requesting the auto headlamps ON)

Battery Voltage

Data

Volts

10.2-14.7 volts

Battery Voltage

Security Data

Volts

0.0-16.0 volts (Varies)

Chime

Output

None /Headlamp /Turn Signal/ Key In Ignition /Device Control

NONE

Content Theft Lamp

Security Data

ON /OFF /FLASHING

OFF

Courtesy Lamp Relay

Input 2

ON /OFF

OFF (Courtesy Lamps OFF)

Courtesy Lamp Relay

Output

ON /OFF

OFF

Courtesy Lamp Timer

Data

SECONDS

0-40 seconds

Daytime Running Lamps

Input 2

ACTIVE /INACTIVE

ACTIVE in the LIGHT state (When the DRL is ON)

Dimming

Output

ACTIVE /INACTIVE

INACTIVE (When the park lamps are OFF)

Dimming Potentiometer

Data

Volts

0.1-12.7 volts (Varies)

Dim Pot Input

Input 2

ACTIVE /INACTIVE

INACTIVE

Dome Lamp Switch

Input 2

ON /OFF

OFF

Dome Override Switch

Input 2

ON /OFF

OFF

Door Handle Switch

Input 1

ACTIVE /INACTIVE

INACTIVE

Door Key Switch

Input 1

ACTIVE /INACTIVE

INACTIVE

Door Lock Relay

Output

ON /OFF

OFF

Door Lock Relay Feedback

Input 1

ON /OFF

OFF

Driver Door Jamb Switch

Input 1

ACTIVE /INACTIVE

INACTIVE (door closed)

ACTIVE (door open)

Driver Door Unlock Relay

Output

ON /OFF

OFF

DRL Relay

Output

ON /OFF

ON (DRL ON)

Dusk

Data

YES / NO

YES (When in the DUSK state)

Flash to Pass Switch

Input 2

ON /OFF

OFF

Front Fog Lamp Relay

Output

ON /OFF

OFF

Front Fog Lamp Switch

Input 2

ON /OFF

OFF (ON when the button is pressed)

Headlamp Power Relay

Output

ON /OFF

ON (When in the MANUAL headlamp position)

OFF (When in the AUTO headlamp position and in the LIGHT State)

Headlamp Request Switch

Input 2

ACTIVE /INACTIVE

ACTIVE (When in the MANUAL headlamp position)

INACTIVE (When in the AUTO headlamp position)

Headlamp Relay Feedback

Input 2

ON /OFF

OFF

High Beam Input

Data

Volts

DRL Beams ON  =  5.9-7.0 volts

Low Beams ON = 11.5-14.0 volts

High Beams ON = 1.2 volts (Varies with vehicle)

High Beam Switch

Input 2

ON /OFF

OFF

Horn Relay

Output

ON /OFF

OFF

Horn Relay Input

Input 1

ACTIVE /INACTIVE

INACTIVE

Ignition 1

Input 1

ACTIVE /INACTIVE

ACTIVE

Ignition 1

Security Data

ACTIVE /INACTIVE

ACTIVE (When Ignition Switch is in the RUN or CRANK position)

Ignition 3

Input 1

ACTIVE /INACTIVE

ACTIVE

Ignition 3

Security Data

ACTIVE /INACTIVE

ACTIVE (When the ignition switch is in the RUN position)

Ignition Power Mode

Input 1

OFF /RUN /CRANK /UNKNOWN

RUN

Inadvertent Power Relay

Output

ON /OFF

ON

Inadvertent Power Timer

Data

SECONDS

0-1216 seconds

Interior Lamp Request

Input 2

ACTIVE /INACTIVE

ACTIVE (When an interior lamp request is made and the inadvertent power relay is OFF)

Interior Lighting Mode

Output

None /Interior /Illuminated Entry /Exit Lighting /Remote Illuminated

NONE

Key In Ignition

Input 1

YES /NO

YES

Left Turn Signal

Input 2

ON /OFF

OFF

Lighting Calibration Number

Module Information 2

NUMERIC

16XXXXXX (Varies with vehicle)

Lighting Suffix

Module Information 2

2 Letters

AA-ZZ (Varies with vehicle)

Manufactures Enable Counter

Module Information 1

0-255

0

Module Part Number

Module Information 1

NUMERIC

16XXXXXX (Varies with vehicle)

Park Brake Switch

Input 1

SET /RELEASED

RELEASED

Park Lamp Relay

Output

ON /OFF

OFF

Park Lamps

Input 2

ON /OFF

OFF

Pass Door Unlock Input

Input 1

ACTIVE /INACTIVE

INACTIVE

RAP Calibration Number

Module Information 2

NUMERIC

16XXXXXX (Varies with vehicle)

RAP Relay

Input 1

ON /OFF

ON

RAP Relay

Output

ON /OFF

ON

RAP Suffix

Module Information 2

2 Letters

AA-ZZ (Varies with vehicle)

RAP Timer

Data

SECONDS

0-1198 seconds

Reminder Calibration Number

Module Information 2

NUMERIC

16XXXXXX (Varies with vehicle)

Reminder Suffix

Module Information 2

2 Letters

AA-ZZ (Varies with vehicle)

Right Turn Signal

Input 2

ON /OFF

OFF

Seat Belt Buckled

Input 1

YES /NO

YES

Security Calibration Number

Module Information 2

NUMERIC

16XXXXXX (Varies with vehicle)

Security Suffix

Module Information 2

2 Letters

AA-ZZ (Varies with vehicle)

Software Design Suffix

Module Information 1

2 Letters

AA-ZZ (Varies with vehicle)

Software Part Number

Module Information 1

NUMERIC

16XXXXXX (Varies with vehicle)

Vehicle Speed

Data

MPH and km/h

Varies with vehicle speed