GM Service Manual Online
For 1990-2009 cars only
Accessory Switch: The scan tool displays Active or Inactive. The state of the accessory switch as monitored by the body control module (BCM).

Ambient Air Temperature Sensor: The scan tool displays -35 to +60°C (-31 to +140°F). The instrument panel cluster (IPC) monitors the voltage at the signal circuit of the ambient air temperature sensor. The voltage is inversely proportional to the measured ambient temperature.

Battery Voltage: The scan tool displays 9-16 volts. The voltage measured at the battery positive voltage circuit to the IPC.

Brake Fluid Level Switch: The scan tool displays On or Off. The IPC monitors the signal circuit of the brake fluid level switch. A closed switch with low brake fluid is displayed as On.

Change Oil Now Command: The scan tool displays On or Off. The state of the change oil indicator as commanded by the IPC.

Cruise Control Active: The scan tool displays Yes or No. This is the state of the cruise control as commanded by the engine control module (ECM).

ECT Sensor: The scan tool displays -40 to +115°C (-40 to +304°F). The ECM 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/Low. The PCM monitors the signal circuit of the engine oil level switch, where an open switch is displayed as Low (low engine oil level).

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

Engine Oil Pressure Sensor: The scan tool displays 0-5 volts. The ECM monitors the engine oil pressure sensor signal circuit where a low voltage indicates low pressure.

Engine Oil Pressure Sensor: The scan tool displays pressure in kPa (psi). The ECM monitors the engine oil pressure sensor signal circuit.

Engine Oil Temperature Calculated: The scan tool displays Celsius (Fahrenheit). This is a calculated value of the engine oil as determined by the ECM.

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

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

Fuel Pump Relay Command: The scan tool displays On or Off. The state of the fuel pump as commanded by the ECM.

Fuel Tank Level Remaining: The scan tool displays 0-100%. The ECM calculates the amount of fuel remaining in the tank based on the input from the fuel level sensor. The IPC receives a class 2 message from the ECM indicating the fuel level percent.

Fuel Tank Rated Capacity: The scan tool displays the fuel tank size in liters.

Headlamp Off Switch: The scan tool displays Active or Inactive. The state of the headlamp switch as monitored by the BCM.

High Beam Switch: The scan tool displays On or Off. The state of the high beam switch as monitored by the BCM.

Ignition 1 Signal: The scan tool displays 9-16 volts. The voltage measured at the battery positive voltage circuit to the IPC.

Ignition 1 Signal: The scan tool displays 9-16 volts. The voltage measured at the ignition 1 voltage circuit to the ECM.

Ignition Accessory Signal: The scan tool displays On or Off. The ECM monitors the position of the ignition switch. On is displayed when the ignition switch is in the Run or ACCY position.

Information Down Switch: The scan tool displays Active or Inactive. The state of the driver information center (DIC) information down switch as monitored by the IPC.

Information Up Switch: The scan tool displays Active or Inactive. The state of the DIC information up switch as monitored by the IPC.

Interior Light Switch: The scan tool displays On or Off. The state of the interior light switch as monitored by the BCM.

Key In Ignition: The scan tool displays Active/Inactive. When the key is in the ignition switch, the scan tool will display Active. This is the state of the ignition switch as monitored by the BCM.

Left Rear Door Ajar Sw.: The scan tool displays Closed or Ajar. The state of the left rear door ajar switch as monitored by the BCM.

Left Turn Signal: The scan tool displays On or Off. The state of left turn signal input detected by the BCM. The indicator turns on when the switch is closed.

LF Door Ajar Switch: The scan tool displays Door Closed or Ajar. The state of the left front door ajar switch as monitored by the BCM.

Low Beam Switch: The scan tool displays On or Off. The state of the low beam switch as monitored by the BCM.

Low Engine Oil Level Lamp Command: The scan tool displays On or Off. The state of the low engine oil level indicator as commanded by the IPC.

Low EOP Lamp Command: The scan tool displays On or Off. The state of the low engine oil pressure indicator as commanded by the IPC.

MIL Circuit History: The scan tool displays OK, or Low. This is the state of the malfunction indicator lamp (MIL) signal circuit as monitored by the IPC.

MIL Circuit History: The scan tool displays OK, Open, Short, or Invalid State. This is the state of the MIL signal circuit as monitored by the ECM.

MIL Command: The scan tool displays On or Off. This is the state of the MIL as commanded by the IPC.

Outside Air Temp: The scan tool displays Counts. This is the state of the ambient air temperature sensor as monitored by the IPC.

Outside Air Temp. Raw: The scan tool displays temperature in Centigrade (Fahrenheit). This is the state of the raw ambient air temperature sensor data as monitored by the IPC.

Outside Air Temp. Filtered: The scan tool displays temperature in Centigrade (Fahrenheit). This is the state of the raw ambient air temperature sensor data as monitored by the IPC.

Page Switch: The scan tool displays Active or Inactive. The state of the DIC page switch as monitored by the IPC.

Park Brake Switch: The scan tool displays Set or Released. The state of the park lamps switch as monitored by the BCM.

Park Lamp Switch: The scan tool displays On or Off. The state of the park lamps switch as monitored by the BCM.

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

RF Door Ajar Switch: The scan tool displays Door Closed or Ajar. The state of the right front door ajar switch as monitored by the BCM.

Right Rear Door Ajar Sw.: The scan tool displays Closed or Ajar. The state of the right rear door ajar switch as monitored by the BCM.

Right Turn Signal: The scan tool displays On or Off. The state of right turn signal input detected by the BCM. The indicator turns on when the switch is closed.

Set/Reset Switch: The scan tool displays Active or Inactive. The state of the DIC set/reset switch as monitored by the IPC.

Vehicle Speed Sensor: The scan tool displays 0-255 km/h (0-159 mph). The ECM monitors the voltage at the signal circuit of the vehicle speed sensor. The voltage is proportional to the vehicle speed.