GM Service Manual Online
For 1990-2009 cars only
2WD High Indicator Light:  This parameter displays On when the transfer case shift control module commands the 2WD high indicator light On. The scan tool displays On or Off.

4WD High Indicator Light: This parameter displays On when the transfer case shift control module commands the 4WD high indicator light On. The scan tool displays On or Off.

4WD Low Active: This parameter displays Yes when the transfer case is currently in the 4WD low lock mode. The scan tool displays Yes or No.

4WD Low Indicator Light: This parameter displays On when the transfer case shift control module commands the 4WD low indicator light On. The scan tool displays On or Off.

Battery Voltage: This parameter displays the voltage measured by the transfer case shift control module at the transfer case shift control module battery feed. The scan tool displays a range of 0-25.5 volts.

Encoder Gear Position: This parameter displays the mode the transfer case is currently in.

Encoder Return Voltage: This parameter displays the voltage measured by the transfer case shift control module at the encoder signal return. The scan tool displays a range of 0-7.5 volts.

Encoder Supply Voltage: This parameter displays the voltage measured by the transfer case shift control module at the 5 volt reference circuit. The scan tool displays a range of 0-7.5 volts.

Ign. Cycles Since Last Current DTC: This parameter displays how many ignition cycles have occurred since last current DTC was set. The scan tool displays a numeric value.

Mode Switch Return Voltage: This parameter displays the return voltage from the transfer case shift control switch. The scan tool displays a range of 0-5 volts.

Mode Switch Selected: This parameter displays the transfer case shift control switch button currently depressed by the driver.

Motor A/B Current: The parameter displays the actual current flowing through the circuit.

Neutral Indicator Light: This parameter displays On when the transfer case shift control module commands the neutral indicator light On. The scan tool displays On or Off.

Service 4WD Lamp: This parameter displays On if the transfer case shift control module commands the Service 4WD lamp, or message, On. The scan tool displays On or Off.