GM Service Manual Online
For 1990-2009 cars only

The automatic transfer case (ATC) Scan Tool Data Definitions contain a brief description of all ATC related parameters available on the scan tool. The scan tool data list is arranged in alphanumeric order.

ATC Slip Speed: The scan tool displays a range of 0-8192 RPM. This parameter indicates the RPM difference between the front and rear propshafts.

AWD Enabled: The scan tool displays Yes or No. This parameter indicates if the transfer case shift control module is currently attempting to prevent front-to-rear propshaft slip.

Front Propshaft Signal Fault: The scan tool displays Yes or No. This parameter indicates Yes when a DTC C0305, Front Speed Sensor Malfunction, has been detected. The code will not set unless the fault is present for 30 seconds.

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 the part number of the module.

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 the transfer case shift control module 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 transfer case encoder motor during the last slip event.

Motor Ground Circuit Open: The scan tool displays Yes or No. This parameter indicates YES when there is no current flow, system voltage is sensed at both Motor A and Motor B terminals, the transfer case encoder motor relay is commanded On, and the transfer case transistor is commanded On. The transfer case encoder motor relay and the transfer case transistor are integral to the transfer case shift control module.

Motor A or B Circuit Fault: The scan tool displays Yes or No. Yes indicates that one of the above motor circuit faults has been detected.

Motor A or B Circuit Open: The scan tool displays Yes or No. This parameter indicates Yes when the transfer case encoder motor relay is commanded On, the transfer case transistor is commanded Off, and there is no current flow and no voltage sensed at the Motor B terminal.

Motor A or B Short to Gnd.: The scan tool displays Yes or No. This parameter indicates Yes when the transfer case encoder motor relay is commanded On, the transfer case transistor is commanded Off, there is current is flowing through part of the circuit to a short to ground, and there is no voltage sensed at the Motor B terminal.

Motor A or B Short to Volts: The scan tool displays Yes or No. This parameter indicates Yes when the transfer case encoder motor relay is commanded off, and voltage is sensed on either the Motor A or Motor B terminals.

Rear Propshaft Signal Fault: The scan tool displays Yes or No. This parameter indicates Yes when a DTC C0300, Rear Speed Sensor Malfunction, has been detected. The code will not set unless the fault is present for 30 seconds.

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

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

Software ID: The scan tool displays a numeric value indicating which version of software is currently installed in the transfer case shift control module.

Total Slippage: The scan tool displays a range of 0-8,192 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).