GM Service Manual Online
For 1990-2009 cars only
4WD Signal (If Equipped): The scan tool displays Enabled or Disabled. The powertrain control module (PCM) monitors the signal circuit of the 4WD switch. A closed switch is displayed as Enabled.

4WD Low Signal (If Equipped): The scan tool displays Enabled or Disabled. The PCM monitors the signal circuit of the 4WD low switch. A closed switch is displayed as Enabled.

ABS Lamp: The scan tool displays On or Off. The state of the antilock brake system (ABS) indicator as commanded by the instrument panel cluster (IPC).

Air Bag Lamp: The scan tool displays On or Off. The state of the air bag indicator as commanded by the IPC.

Battery: The scan tool displays 0-19 volts. The voltage at the battery positive voltage circuit of the IPC.

Battery 1 Low Current: The scan tool displays 0-19 volts. The voltage measured at the battery positive voltage circuit of the driver/passenger door module (DDM/PDM).

Battery 2 High Current: The scan tool displays 0-19 volts. The voltage measured at the battery positive voltage circuit of the driver/passenger door module.

Battery Voltage: The scan tool displays 0-19 volts. The voltage measured at the battery positive voltage circuit of the IPC.

Brake Lamp: The scan tool displays On or Off. The state of the brake system indicator as commanded by the IPC.

Check Gages Lamp: The scan tool displays On or Off. The state of the CHECK GAGES indicator as commanded by the IPC.

Coolant Level Switch: The scan tool displays Ok or Low. The PCM monitors the coolant level switch signal circuit where a closed switch is displayed as Ok.

Cruise Control: The scan tool displays On or Off. The state of the cruise indicator as commanded by the IPC.

DIC Fuel: The scan tool displays On or Off. The IPC monitors the Fuel button of the driver information center (DIC) switch. A closed switch is displayed as On.

DIC Personalization: The scan tool displays On or Off. The IPC monitors the personalization button of the DIC switch. A closed switch is displayed as On.

DIC Select: The scan tool displays On or Off. The IPC monitors the Select button of the DIC switch. A closed switch is displayed as On.

DIC Trip: The scan tool displays On or Off. The IPC monitors the Trip button of the DIC switch. A closed switch is displayed as On.

Displayed Coolant Temperature: The scan tool displays 38-128°C (100-260°F). The displayed coolant temperature gage value in the IPC. This value may slightly differ from the monitored coolant temperature.

Displayed Fuel Level: The scan tool displays 0-100%. The displayed fuel gage value in the IPC. This value may slightly differ from the monitored fuel level.

Displayed Odometer: The scan tool displays 0-999999 km (miles). The displayed odometer value in the IPC.

Displayed Oil Pressure: The scan tool displays 0-682 kPa (0-99 psi). The displayed oil pressure gage value in the IPC.

Door Ajar Switch: The scan tool displays On or Off. The driver door module/passenger door module (DDM/PDM) monitors the signal circuit of the door ajar switch. An open switch is displayed as On with the door open.

ECT Sensor: The scan tool displays -40 to +151°C (-40 to +304°F). The PCM monitors the voltage at the signal circuit of the engine coolant temperature sensor. The voltage is inversely proportional to the engine coolant temperature.

Engine Oil Level Switch: The scan tool displays OK or Low. The PCM monitors the signal circuit of the engine oil level and temperature sensor. A closed switch is displayed as Low with low engine oil level.

Engine Oil Life Remaining: The scan tool displays 0-100%. The PCM calculates the remaining engine oil life.

Engine Oil Pressure Sensor: The scan tool displays 0-5 volts. The PCM monitors the engine oil pressure sensor signal circuit.

Engine Oil Pressure Switch: The scan tool displays OK or Low. The PCM monitors the signal circuit of the engine oil pressure switch. A closed switch is displayed as Low with low engine oil pressure.

Engine Speed: The scan tool displays 0-9999 RPM. The IPC monitors the engine speed signal circuit from the PCM.

Engine Speed: The scan tool displays 0-9999 RPM. The PCM computes the engine speed. It should remain close to desired idle under various engine loads with the engine idling.

Fasten Seat Belts: The scan tool displays On or Off. The state of the fasten safety belt indicator as commanded by the IPC.

Fuel Level Sender: The scan tool displays 0-100%. The PCM calculates the amount of fuel remaining in the tank based on the input from the fuel level sensor.

Fuel Level Sensor: The scan tool displays 0-5 volts. The PCM calculates the amount of fuel remaining in the tank based on the input from the fuel level sensor.

Fuel Level Sensor: The scan tool displays 0-100%. The PCM calculates the amount of fuel remaining in the tank based on the input from the fuel level sensor.

Fuel Level Sensor Rear Tank (If Equipped): The scan tool displays 0-5 volts. The PCM monitors the rear tank fuel level sensor signal circuit where 0 V is an empty tank.

Fuel Tank Level Remaining: The scan tool displays liters (gallons). This is the amount of fuel remaining in the fuel tank as determined by the PCM.

Fuel Tank Level Remaining: The scan tool displays 0-100%. The scan tool displays in percentage the amount of fuel remaining in the fuel tank as determined by the PCM.

Fuel Tank Rated Capacity: The scan tool displays liters (gallons). This is the fuel tank rated capacity as determined by the PCM.

Headlamp Switch:  The scan tool displays Active or Inactive. The body control module (BCM) monitors the signal circuit of the headlamp switch. A closed switch is displayed as Active.

High Beam Lamp: The scan tool displays On or Off. The state of the high beam indicator as commanded by the IPC.

Hood Ajar Switch: The scan tool displays Active or Inactive. The BCM monitors the signal circuit of the hood ajar switch. An open switch is displayed as Active with the door open.

Ignition 0: The scan tool displays On or Off. The state of the ignition 0 voltage circuit as monitored by the BCM.

Ignition 1: The scan tool displays On or Off. The state of the ignition 1 voltage circuit as monitored by the BCM.

Ignition 3: The scan tool displays On or Off. The state of the ignition 3 voltage circuit as monitored by the BCM.

Ignition 1 Signal: The scan tool displays 0-19 volts. The voltage measured at the ignition 1 voltage circuit of the PCM.

Ignition 1 Voltage: The scan tool displays 0-19 volts. The voltage measured at the ignition 1 voltage circuit of the IPC.

Ignition Since Current DTC: The scan tool displays 0-50. The IPC counts the number of times the ignition is cycled since the current DTC was set.

Key In Ignition: The scan tool displays Yes or No. The BCM monitors the signal circuit of the key in ignition switch. A closed switch is displayed as Yes with the key in the ignition.

Left Rear Door Ajar Sw: The scan tool displays On or Off. The BCM monitors the signal circuit of the left rear door ajar switch. An open switch is displayed as On with the door open.

Left Turn Input: The scan tool displays Open or Closed. The IPC monitors the left turn signal supply voltage circuit. An active turn signal toggles between Open and Closed.

Low Fuel Lamp: The scan tool displays On or Off. The state of the low fuel indicator as commanded by the IPC.

Low Oil Lamp Command: The scan tool displays On or Off. This the state of the low oil lamp command as monitored by the PCM.

Low Washer Fluid: The scan tool displays OK or Low. The state of the low washer fluid switch as monitored by the IPC.

MIL (Malfunction Indicator Lamp) Command: The scan tool displays On or Off. This is the commanded state of the malfunction indicator lamp (MIL) by the PCM.

Monitored Coolant Temperature: The scan tool displays 40-419°F (40-215°C). The IPC monitored coolant temperature data as provided by the PCM via the class 2 serial data link.

Monitored Fuel Level: The scan tool displays 0-100%. The IPC monitored fuel level percent as provided by the PCM via the class 2 serial data link.

Monitored Oil Pressure: The scan tool displays 0-682 kPa (0-99 psi). The IPC monitored oil pressure as provided by the PCM via the class 2 serial data link.

Park Brake Switch:  The scan tool displays Set or Released. The BCM monitors the signal circuit of the park brake switch. A closed switch is displayed as Set.

Parklamp Switch: The scan tool displays Active or Inactive. The BCM monitors the signal circuit of the parklamp switch. A closed switch is displayed as Active.

PRND321 State: The scan tool displays Park, Reverse, Neutral, Drive, 1st, 2nd or 3rd. The state of the PRND321 as commanded by the IPC.

Rear Gate/Door: The scan tool displays Open or Closed. The state of the liftgate switch as monitored by the IPC.

Reduced Engine Power: The scan tool displays Inactive or Active. This is the state of the Reduced Engine Power indicator as monitored by the PCM.

Right Rear Door Ajar Sw: The scan tool displays On or Off. The BCM monitors the signal circuit of the right rear door ajar switch. An open switch is displayed as On with the door open.

Right Turn Input: The scan tool displays Open or Closed. The IPC monitors the right turn signal lamps supply voltage circuit. An active turn signal toggles between Open and Closed.

Security Lamp: The scan tool displays On or Off. The state of the SECURITY indicator as commanded by the IPC.

Service 4WD: The scan tool displays On or Off. The state of the Service 4WD indicator as commanded by the IPC.

Trans. Fluid Temp: The scan tool displays -40 to +215°C (-40 to +419°F). This is the PCM monitored transmission fluid temperature data as provided to the IPC via the class 2 serial data link.

Trip Odometer A: The scan tool displays miles. The IPC calculates trip odometer information from the vehicle speed data received from the PCM.

Trip Odometer B: The scan tool displays miles. The IPC calculates trip odometer information from the vehicle speed data received from the PCM.

Trip Reset Switch: The scan tool displays Active or Inactive. The IPC monitors the TRIP RESET button of the DIC switch. A closed switch is displayed as Active.

Vehicle Speed: The scan tool displays 0-255 km/h (0-155 mph). The IPC monitors the vehicle speed signal circuit from the PCM.

Vehicle Speed Sensor: The scan tool displays 0-255 km/h (0-155 mph). The PCM monitors the voltage at the signal circuit of the vehicle speed sensor. The voltage is proportional to the vehicle speed.