GM Service Manual Online
For 1990-2009 cars only
Table 1: Scan Tool Data Parameters
Table 2: Scan Tool Output Controls

Scan Tool Data Parameters

Parameter

Expected Value

Description

Operating Conditions: Engine Idling/Radiator Hose Hot/Closed Throttle/Park or Neutral/Closed Loop/Accessories OFF, unless otherwise noted.

2WD High Indicator Light

On

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

Off

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

No

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

Off

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

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

2WD

This parameter displays the mode the transfer case is currently in.

Encoder Return Voltage

0-7.5 V

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

0-7.5 V

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

Varies

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

0-5 V

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

Off

This parameter displays the transfer case shift control switch button currently depressed by the driver.

Motor A Current

Varies

The parameter displays the actual current flowing through the circuit.

Motor B Current

Varies

Neutral Indicator Light

Off

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

Off

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.

Scan Tool Output Controls

Output Control

Description

Refer to the scan tool manual for complete scan tool operating instructions.

2WD High Indicator Light

This function allows the technician to command the 2WD high indicator light, within the transfer case shift control switch, on or off.

4WD High Indicator Light

This function allows the technician to command the 4WD high indicator light, within the transfer case shift control switch, on or off.

4WD Low Indicator Light

This function allows the technician to command the 4WD low indicator light, within the transfer case shift control switch, on or off.

ATC Motor A Control

This function allows the technician to energize the motor, causing it to shift the transfer case through all five modes. Motor control A moves in the opposite direction as motor control B.

ATC Motor B Control

This function allows the technician to energize the motor, causing it to shift the transfer case through all five modes. Motor control B moves in the opposite direction as motor control A.

Neutral Indicator Light

This function allows the technician to command the neutral indicator light, within the transfer case shift control switch, on or off.