The Automatic Transfer Case (ATC) Scan Tool Data Definitions contain a brief description of all ATC related parameters available on the scan tool. The list is in the order that the parameters appear on the scan tool.

Commanded Mode Indicator: The scan tool displays a range of 2WD to 4WD Low. This parameter indicates the current mode in which ATC is operating.

Encoder Circuit A: The scan tool displays On or Off. This parameter indicates whether transfer case shift control module is sensing voltage on the Encoder Circuit A (On=<1 volt, Off=>3 volts).

Encoder Circuit B: The scan tool displays On or Off. This parameter indicates whether transfer case shift control module is sensing voltage on the Encoder Circuit B (On=<1 volt, Off=>3 volts).

Encoder Circuit C: The scan tool displays On or Off. This parameter indicates whether transfer case shift control module is sensing voltage on the Encoder Circuit C (On=<1 volt, Off=>3 volts).

Encoder Circuit P: The scan tool displays On or Off. This parameter indicates whether transfer case shift control module is sensing voltage on the Encoder Circuit P (On=<1 volt, Off=>3 volts).

Encoder Gear Position: The scan tool displays a range of 2WD to 4WD Low. This parameter indicates the actual transfer case sector shaft position as sensed by the encoder.

Front Axle Switch: The scan tool displays Locked or Unlocked. This parameter indicates the feedback states of the front axle switch.

Front Axle Switch Requested: The scan tool displays Yes or No. This parameter indicates if the front axle switch has been requested by the transfer case shift control module.

GM Part Number: The scan tool displays an eight-digit number. This parameter indicates the transfer case shift control module GM software number.

Ignition 3: The scan tool displays a range of 0-25.5 volts. This parameter indicates the voltage measured by the transfer case shift control module at its ignition feed.

Mode Switch Selected: The scan tool displays On or Off. This parameter indicates the ATC mode switch button currently depressed by the driver.

Neutral Indicator Light: The scan tool displays On or Off. This parameter indicates if the Neutral Indicator Light is being commanded by the transfer case shift control module.

Park Switch: The scan tool displays Open or Closed. This parameter indicates the feedback states of the Park/Neutral Switch.

Service 4WD Lamp: The scan tool displays On or Off. This parameter indicates if the Service 4WD Lamp is being commanded by the transfer case shift control module.

Slip Adapt PWM: The scan tool displays a range of 0-100 percent. This parameter indicates the duty cycle applied to the ATC motor.

Software ID: The scan tool displays a four-digit number. This parameter indicates the transfer case shift control module calibration version number.

Throttle Anticipation Mode: The scan tool displays Enabled or Disabled. This parameter changes from Disabled to Enabled when the vehicle starts movement from a stop position, light to heavy throttle is applied, and is currently in AWD mode. Throttle Anticipation Mode helps eliminate the clunking sound normally associated with front axle engagement.

TP (Throttle Position) Angle: The scan tool displays a range of 0-100 percent. The TP Angle is computed by the PCM from the TP sensor voltage. The TP Angle should read 0 percent at idle and 100 percent at Wide-Open Throttle (WOT).

2WD High Indicator Light: The scan tool displays On or Off. This parameter indicates if the 2WD High Indicator Light is being commanded by the transfer case shift control module.

4WD High Indicator Light: The scan tool displays On or Off. This parameter indicates if the 4WD High Indicator Light is being commanded by the transfer case shift control module.

4WD Lamp Open: The scan tool displays Yes or No. This parameter indicates if the 4WD Lamp circuit is open or shorted to ground, when a Yes is displayed.

4WD Lamp Shorted: The scan tool displays Yes or No. This parameter indicates if the 4WD Lamp circuit is shorted to voltage or a loss of driver ground, when a Yes is displayed.

4WD Low Indicator Light: The scan tool displays On or Off. This parameter indicates if the 4WD Low Indicator Light is being commanded by the transfer case shift control module.