Transfer Case Shift Control Module Scan Tool Information. GMC Truck Envoy

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2009 🢒 Envoy - 2WD 🢒 Power and Signal Distribution 🢒 Data Communications 🢒 Transfer Case Shift Control Module Scan Tool Information

Table 1:	Scan Tool Data Parameters
Table 2:	Scan Tool Output Controls

Scan Tool Data Parameters

Parameter	Expected Value	Description
Operating Conditions: Engine is at idle, upper radiator hose is hot, closed throttle, gear is in PARK or NEUTRAL and accessories are OFF.
2WD High Indicator Light	Off	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.
ATC Application	Varies	This parameter displays the model number assigned to the transfer case. The scan tool displays a numeric value.
ATC Slip Speed	0	This parameter displays the RPM difference between the front and rear propshafts. The scan tool displays a range of 0-8,192 RPM.
Auto 4WD Indicator Light	On	This parameter displays On when the transfer case shift control module commands the auto 4WD 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.
Current Slip Adapts	Varies	This parameter displays corrective adjustments made by the transfer case shift control module for wheel slip events. The scan tool displays a numeric value.
Encoder Gear Position	Varies	This parameter displays the mode the transfer case is currently in.
Encoder Return Voltage	0-5 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	0-5 V	This parameter displays the voltage measured by the transfer case shift control module at the 5V reference circuit. The scan tool displays a range of 0-7.5 volts.
Front Axle Requested	Yes	This parameter displays Yes if the transfer case shift control module requests the front axle switch On. The scan tool displays Yes or No.
Front Axle Switch	Locked	This parameter displays the feedback states of the front propshaft. The scan tool displays Locked or Unlocked.
Front Propshaft Speed	0	This parameter displays the rotational speed of the front propshaft. The scan tool displays a range of 0-8,192 RPM.
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	Varies	This parameter displays the transfer case shift control switch button currently depressed by the driver.
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.
Rear Propshaft Speed	0	This parameter displays the rotational speed of the rear propshaft. The scan tool displays a range of 0-8,192 RPM.
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.
Slip Adapt PWM	0	This parameter displays the duty cycle applied to the transfer case encoder motor. The scan tool displays a range of 0-100 percent.
Total Slippage	0	This parameter displays the total slippage of both the front and rear propshafts. The scan tool displays a range of 0-8,192 RPM.
Transfer Case Lock	Disabled	This parameter displays Enabled if the transfer case shift control module commands the transfer case motor brake On. The scan tool displays Enabled or Disabled.

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.
Auto 4WD Indicator Light	This function allows the technician to command the auto 4WD indicator light, within the transfer case shift control switch, on or off.
Engage Front Axle	This function allows the technician to engage and disengage the front axle actuator. When the front axle actuator is engaged, the front axle becomes a live axle, causing the front propshaft to turn.
Neutral Indicator Light	This function allows the technician to command the neutral indicator light, within the transfer case shift control switch, on or off.
Transfer Case Lock	This function allows the technician to turn the transfer case lock on and off. With the transfer case lock on, the transfer case cannot be shifted.