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 it appears on the scan tool.

ATC Slip Speed: The scan tool displays a range of 0-8,192 RPM. This parameter indicates the RPM difference between the front and rear propshafts.

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

Commanded Mode Indicator: The scan tool displays a range of Auto 4WD 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 Auto 4WD 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 Request: 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.

Front Propshaft Speed: The scan tool displays a range of 0-8192 RPM. This parameter indicates the rotational speed of the front propshaft.

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.

Last Adapt Highest PWM: The scan tool displays a range of 0-100 percent. This parameter indicates the highest duty cycle applied to the ATC motor during the last slip event.

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.

Rear Propshaft Speed: The scan tool displays a range of 0-8192 RPM. This parameter indicates the rotational speed of the rear propshaft.

Rear Slippage: The scan tool displays a range of 0- 8192 RPM. This parameter indicates the total slippage of the rear propshaft.

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 Mode: The scan tool displays Enabled or Disabled. This parameter indicates if the transfer case shift control module is currently attempting to prevent front to rear propshaft slip.

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

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.

Total Slippage: The scan tool displays a range of 0-8192 RPM. This parameter indicates the total slippage of both the front and rear propshafts.

TP 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).

Transfer Case Lock: The scan tool displays Enabled or Disabled. This parameter indicates if the transfer case shift control module is commanding the transfer case motor brake On.

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 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.