GM Service Manual Online
For 1990-2009 cars only

Use the Scan Tool Data Display Values and Definitions Information in order to assist in diagnosing vehicle malfunctions. Compare the vehicles actual scan tool data with the typical data display value table information. Use the data information in order to aid in understanding the nature of the problem when the vehicle does not match with the typical data display values.

The scan tool data values were taken from a known good vehicle under the following conditions:

    • The ignition switch is in the ON position.
    • The engine is not running.
    • The vehicle is in PARK.

DRL Relay

This body control module output displays the state of the daytime running lamps (DRL) relay. When the proper conditions are present for the BCM to command on the DRL relay by providing ground to the relay, ON is displayed.

DRL Relay Feedback

This body control module input displays the state of the daytime running lamps (DRL) relay. When the BCM senses that the DRL relay is on, ACTIVE is displayed.

Park Lamp Input

This body control module input displays the state of the park lamps. When the BCM senses that the park lamps are illuminated, ON is displayed.

Low Beam Feedback

This body control module input displays the state of the low beam headlamps. When the BCM senses that the normal low beam headlamps are illuminated, the operating voltage of the low beam headlamps is displayed. When the BCM senses that the DRLs are active, the reduced operating voltage of the DRLs is displayed.

High Beam Feedback

This body control module input displays the state of the high beam headlamps. When the BCM senses that the normal high beam headlamps are illuminated, the operating voltage of the high beam headlamps is displayed. When the BCM senses that the DRLs are active, the reduced operating voltage of the DRLs is displayed.

Front Fog Lamp Switch

The BCM uses this input to determine if the fog lamps have been requested on. When the fog lamps switch is pressed once, ON is displayed on the scan tool. When the fog lamp switch is pressed again, OFF is displayed.

Front Fog Lamp Relay

This BCM output displays the state of the fog lamp relay. When the proper conditions are present for the BCM to command on the fog lamp relay by providing ground to the relay, ON is displayed.

Fog Lamp Relay Feedback

This BCM input displays the state of the fog lamp relay. When the BCM senses that the fog lamp relay is on, ACTIVE is displayed.

Interior Dim Pot

The BCM uses this input to determine the requested level of the instrument panel dimming lamps. When full intensity is requested, the scan tool will display less than 1 volt. When full dim is requested, the scan tool will display approximately battery voltage. The voltage will vary within this range depending on the position of the lamp dimmer switch.

Interior Lamp Output

This BCM output displays the state of the interior courtesy lamps. When the BCM is commanding on the interior courtesy lamps by providing ground to the lamps, ON is displayed.

Interior Lamp Feedback

This BCM input displays the state of the interior courtesy lamps. When the BCM senses that the lamps are on, ACTIVE is displayed.

Driver Door Ajar Switch

This BCM input is used to determine if the driver door is open. The BCM uses this input to perform various functions such as chimes and interior lamp control. ON is displayed when the driver door is open.

Passenger Door Ajar Switch

This BCM input is used to determine if a passenger door is open. The BCM uses this input to perform various functions such as chimes and interior lamp control. ON is displayed when a passenger door is open.

Inadvert. Power Output

This BCM output displays the state of the inadvertant power relay that is internal to the BCM. The BCM uses this output to provide battery voltage to the courtesy lamps. If the BCM senses that a lamp has been illuminated for approximately 20 minutes after exiting the vehicle, the BCM will turn off the inadvertant power relay to protect the battery from run-down.

Inadvert. Power Feedback

This BCM input displays the state of the inadvertant power relay. When the BCM senses that the relay is on, ACTIVE is displayed.

Cargo Lamp On

This input to the BCM is used to determine if the rear compartment lid is open or closed. If the rear compartment lamp is on, the scan tool displays ON. The BCM uses this input for theft deterrent purposes.