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.
ALC Light Sensor: This BCM input is used to determine the amount of ambient light present. It has a voltage range of 0.4 volts (light) to 4.4 volts (dark).

Battery 1: This BCM input is used to determine the available system voltage of the vehicle's battery.

Dome Lamp Command: This BCM input shows the requested state of the dome lamp. On is displayed when the dome lamp is requested.

Dome Lamp Feedback: This BCM input is used to determine the state of the dome lamp. Low is displayed when the dome lamp is active.

Driver Door 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. Low is displayed when the driver door is open.

DRL Relay Command: 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 output displays the state of the daytime running lamps (DRL) relay. Low is displayed when the DRL relay is active.

Headlamp Fdbk.: This BCM output displays the state of the headlamps. Low is displayed when the headlamps are active.

Inadvertent Power Cmd.: This BCM output displays the state of the inadvertent 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 inadvertent power relay to protect the battery from run-down. On is displayed when the inadvertent power circuit is active.

Inadvertent Power Fdbk.: This BCM output displays the state of the inadvertent power relay. Low is displayed when the inadvertent power relay is active.

I/P Dimmer Input: The BCM uses this input to determine the requested intensity of the I/P lamps. A voltage range of 0.57 volts (full intensity illumination) to 4 volts (lowest intensity illumination) is shown.

I/P Dimmer Output: The BCM uses this output to control the intensity of the I/P lamps. A % Duty Cycle (DC) range of 100% (full intensity illumination) to 19% (lowest intensity illumination) is shown.

Key In Ignition: The BCM uses this input to determine if the ignition key is inserted into the ignition cylinder. Yes is displayed if a key is present in the ignition cylinder.

Low Beam Input: 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, a voltage reading of approximately 4.8 volts is displayed. When the low beam headlamps are not illuminated, battery voltage should be displayed.

Low Beam Input = DRL: This body control module input displays the state of the daytime running lamps (DRL). Yes is displayed when the DRLs are active.

Low Beam Input = High: This body control module input displays the state of the low beam headlamps. When the BCM senses that the low beam headlamps are illuminated, No is displayed.

Low Beam Input = Off: 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, No is displayed.

Low Beam Switch: 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, On is displayed.

Parklamp Cmd.: This body control module output displays the commanded state of the parklamp relay. When the parklamp relay is requested, On is displayed.

Parklamp 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.

Parklamp Switch: This body control module input displays the state of the park lamp switch. When the BCM senses that the headlamp switch is in the headlamp or park lamp position, On is displayed.

Pass Door Switches: 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. Low is displayed when a passenger door is open.