GM Service Manual Online
For 1990-2009 cars only
Battery 1: The scan tool displays 0-19 volts. This is the voltage at the battery positive voltage circuit of the body control module (BCM).

Coolant Gauge Position: The scan tool displays 0-100%. The BCM receives a serial data message from the powertrain control module (PCM) regarding the engine coolant temperature and converts the data to percentage.

Driver Door Switch: The scan tool displays Open or Closed. The state of the driver door switch as commanded by the BCM.

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 Life Left 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 where a low voltage indicates low pressure.

Engine Oil Pressure Switch: The scan tool displays OK or Low. The state of the engine oil pressure switch as commanded by the PCM.

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

Fuel Gauge Position: The scan tool displays 0-100%. The BCM calculates the amount of fuel remaining in the tank based on the serial data messages from the PCM regarding fuel level.

Fuel Level Sensor: The scan tool displays the state of the fuel level in percent. The PCM monitors the signal circuit of the fuel level sensor and displays the current fuel percentage.

Fuel Level Sensor: The scan tool displays 0-5 volts. The PCM monitors the signal circuit of the fuel level sensor and displays the current voltage.

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

I/P Dimmer Input: The scan tool displays Volts. The BCM monitors the voltage from the dimmer switch.

I/P Dimmer Output: The scan tool displays the % duty cycle. The BCM will indicate 0-100% of the dimmer switch duty cycle.

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

Ignition 2 Input: The scan tool displays On or Off. The state of the ignition 2 voltage circuit as monitored by the BCM.

Ignition 1 Signal: The scan tool displays 0-16 V. The ignition 1 signal represents the system voltage detected by the PCM at the ignition voltage circuit.

Key in Ignition: The scan tool displays Yes or No. The state of the key in ignition switch as commanded by the BCM.

Liftgate Ajar Switch: The scan tool displays Open or Closed. The state of the liftgate ajar switch as monitored by the BCM.

Low Beam Input: The scan tool displays Volts. This input displays the voltage supplied to the body control module.

Low Brake Fluid: The scan tool displays Yes or No. The state of the brake fluid level switch as commanded by the BCM.

Low Coolant: The scan tool displays On or Off. The state of the coolant level switch as commanded by the BCM.

Oil Life Reset Switch: The scan tool displays On or Off. The BCM receives an input from the oil life reset switch (in the underhood fuse block) indicating On when the engine oil needs to be changed.

Pass Door Switches: The scan tool displays Open or Closed. The state of the passenger door switches as monitored by the BCM.

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

Parklamp Switch: The scan tool displays On or Off. The state of the parklamp 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 PCM.

Software Date Day: The scan tool displays the day the software was created for the instrument panel cluster (IPC) installed in the vehicle.

Software Date Month: The scan tool displays the month the software was created for the IPC installed in the vehicle.

Software Date Year: The scan tool displays the year the software was created for the IPC installed in the vehicle.

Software ID: The scan tool displays a numeric value. The identification of the IPC software installed in the vehicle.

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