GM Service Manual Online
For 1990-2009 cars only
A/C Evap. Temperature Sensor: The scan tool displays -39 to +140°C (-38 to +284°F). The voltage applied to the HVAC control module input from the evaporator temperature sensor is converted to a temperature value.

A/C High Side Pressure Sensor: The scan tool displays 0-5 volts. The voltage applied to the ECM input for the A/C refrigerant pressure sensor.

A/C High Side Pressure Sensor: The scan tool displays 0-3450 kPa (0-500 psi). The voltage applied to the ECM input from the A/C refrigerant pressure sensor is converted to a pressure value.

Ambient Air Temp. Sensor: The scan tool displays -40 to +215°C (-40 to +419°F). The current value of the ambient air temperature display on the HVAC control module.

Aux. Mode Door Actual: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the aux mode door position input of the HVAC control module.

Aux. Mode Door Command: The scan tool displays 0-255 counts (0-5.00 volts). The desired position of the aux mode actuator as determined by the HVAC control module.

Aux. Temp Dr. Position: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the aux temperature door position input of the HVAC control module.

Aux. Temp Dr. Motor Command: The scan tool displays 0-255 counts (0-5.00 volts). The desired position of the aux temperature actuator as determined by the HVAC control module.

Aux. Blower Motor PWM: The scan tool displays the control decision for the aux blower motor speed as determined by the aux HVAC control module. The scan tool displays 100% when the aux blower motor is commanded to maximum speed. The scan tool displays 0% when the aux blower motor is commanded OFF.

Auxiliary Air Temp Door: The scan tool displays Off and On selections. The selection drives the actuator to its minimum and maximum positions when commanded in both directions.

Auxiliary Mode Door: The scan tool displays Off and On selections. The selection drives the actuator to its minimum and maximum positions when commanded in both directions.

Auxiliary Blower Motor: The scan tool displays Off and On selections. The selection commands the blower speed to its minimum and maximum when commanded On and Off.

A/C Request Signal: The scan tool displays YES/NO. The HVAC module receives an input request when the HVAC module is turned On.

A/C Relay Command: The scan tool displays On and Off. The HVAC module receives an input request for A/C On then the HVAC module outputs a ground signal to activate the A/C relay.

A/C Relay Circuit Status: This displays the status of the relay control circuit. It can display incomplete, short to ground, short to voltage or open.

A/C Off For WOT: The scan tool displays YES/NO. The state of the A/C request related to wide open throttle.

A/C Pressure Disable: The scan tool displays YES/NO. The state of the A/C refrigerant pressure sensor and circuitry.

A/C Disengage 1 History: The scan tool displays None, A/C Pressure, Engine Speed, Battery Voltage, Stall Prevention, RPM Unstable, WOT, Launch Performance or Coolant Hot. The scan tool displays None if OK.

A/C Disengage 2 History: The scan tool displays None, A/C Pressure, Engine Speed, Battery Voltage, Stall Prevention, RPM Unstable, WOT, Launch Performance or Coolant Hot. The scan tool displays None if OK.

A/C Disengage 3 History: The scan tool displays None, A/C Pressure, Engine Speed, Battery Voltage, Stall Prevention, RPM Unstable, WOT, Launch Performance or Coolant Hot. The scan tool displays None if OK.

A/C Disengage 4 History: The scan tool displays None, A/C Pressure, Engine Speed, Battery Voltage, Stall Prevention, RPM Unstable, WOT, Launch Performance or Coolant Hot. The scan tool displays None if OK.

A/C Disengage 5 History: The scan tool displays None, A/C Pressure, Engine Speed, Battery Voltage, Stall Prevention, RPM Unstable, WOT, Launch Performance or Coolant Hot. The scan tool displays None if OK.

A/C Disengage 6 History: The scan tool displays None, A/C Pressure, Engine Speed, Battery Voltage, Stall Prevention, RPM Unstable, WOT, Launch Performance or Coolant Hot. The scan tool displays None if OK.

A/C Disengage 7 History: The scan tool displays None, A/C Pressure, Engine Speed, Battery Voltage, Stall Prevention, RPM Unstable, WOT, Launch Performance or Coolant Hot. The scan tool displays None if OK.

A/C Disengage 8 History: The scan tool displays None, A/C Pressure, Engine Speed, Battery Voltage, Stall Prevention, RPM Unstable, WOT, Launch Performance or Coolant Hot. The scan tool displays None if OK.

A/C Relay: The engine must be running and the ECM must receive an A/C request from the HVAC control module in order to enable the output control. The ECM de-energizes the A/C compressor clutch relay when you select OFF. The relay remains de-energized until you select ON.

A/C Relay: The engine must be running and the ECM must receive an A/C request from the HVAC control module in order to enable the output control. The ECM de-energizes the A/C compressor clutch relay when you select OFF. The relay remains de-energized until you select ON.

Backlight Dimming: The scan tool displays Off and On selections. When commanded On the backlighting is illuminated when commanded Off the Backlights are Off.

Blower Motor: The scan tool displays Off and On selections. The selection commands the blower speed to its minimum and maximum when commanded On and Off.

Blower Motor Relay Cmd.: The scan tool displays On and Off. When the HVAC control module grounds the blower motor relay the scan tool displays On.

Blower Motor Speed command: The scan tool displays 0-100%. The scan tool displays the control decision for the blower motor speed as determined by the HVAC control module. The scan tool displays 100% when the blower motor is commanded to maximum speed. The scan tool displays 0% when the blower motor is commanded OFF.

Coolant Temperature: The scan tool displays -39 to +140°C (-38 to +284°F) . The voltage applied to the ECM input from the engine coolant temperature sensor is converted to a temperature value and transmitted in a GMLAN message to the HVAC control module.

Display Test: The scan tool displays Off and On selections. When commanded Off the LED display on the HVAC module is blank. When commanded back On the LED displays the original settings displayed before being commanded Off.

Display Test: The scan tool displays Off and On selections. The selection drives the actuator to its minimum and maximum positions when commanded in both directions.

Driver Temp Door: The scan tool displays Off and On selections. The selection drives the actuator to its minimum and maximum positions when commanded in both directions.

Driver Temp. Dr. Motor Commanded: The scan tool displays 0-255 counts (0-5.00 volts). The desired position of the driver air temperature actuator as determined by the HVAC control module.

Driver Temp. Dr. Position: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the driver air temperature door position input of the HVAC control module.

ECT Sensor: The scan tool displays -39 to +140°C (-38 to +284°F) . The voltage applied to the ECM input from the engine coolant temperature sensor is converted to a temperature value.

Inside Air Temp. Sensor Fan: The scan tool displays On and Off. When the inside air temp. sensor fan is commanded On the inside air temp sensor fan scan tool parameter also displays On.

Inside Air Temp. Sensor: The scan tool displays -40 to +215°C (-40 to +419°F). The voltage applied to the HVAC control module input for the inside air temperature sensor is converted to a temperature value.

Left Sunload Sensor: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the left sunload input of the HVAC control module.

Mode Dr. Motor Command: The scan tool displays 0-255 counts (0-5.00 volts). The desired position of the mode actuator as determined by the HVAC control module.

Mode Door Position: The scan tool displays Off and On selections. The selection drives the actuator to its minimum and maximum positions when commanded in both directions.

Mode Door Position: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the mode door position input of the HVAC control module.

Power Down Now: The key must be in the Off position when Power Down Now is selected. Then the scan tool is disconnected to perform a parasitic load test.

Passenger Temp Door: The scan tool displays Off and On selections. The selection drives the actuator to its minimum and maximum positions when commanded in both directions.

Psgr. Temp. Dr. Motor Command: The scan tool displays 0-255 counts (0-5.00 volts). The desired position of the passenger air temperature actuator as determined by the HVAC control module.

Psgr. Temp. Dr. Position: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the passenger air temperature door position input of the HVAC control module.

Rear Defrost State: The scan tool displays On and Off. The display reads On when the HVAC module rear defrost switch is activated.

Recirculation Dr. Motor Command: The scan tool displays 0-255 counts (0-5.00 volts). The desired position of the recirc door actuator as determined by the HVAC control module.

Recirculation Dr. Position: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the recirc door position input of the HVAC control module.

Recirculation Door: The scan tool displays Off and On selections. The selection drives the actuator to its minimum and maximum positions when commanded in both directions.

Right Sunload Sensor: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the right sunload input of the HVAC control module.

Segment Check: The scan tool displays Off and On selections. When commanded Off the LCD display on the HVAC module is blank. When commanded back On the LCD displays all viewable numbers and symbols.

Segment Check: The scan tool displays Off and On selections. When commanded Off the LCD display on the AUX HVAC module is blank. When commanded back On the LCD displays all viewable numbers and symbols.

Vehicle Speed: The scan tool displays Km/h/mph