GM Service Manual Online
For 1990-2009 cars only
ABS Lamp: The scan tool displays On or Off. The requested state of the ABS indicator as commanded by the electronic brake control module (EBCM). The BCM receives a class 2 message from the EBCM. The IPC receives the illumination request from the BCM via the serial peripheral interface (SPI).

Brake Warning Lamp: The scan tool displays On or Off. The requested state of the brake indicator as commanded by the BCM or the electronic brake control module (EBCM). The BCM receives a class 2 message from the EBCM. The IPC receives the illumination request from the BCM via the serial peripheral interface (SPI).

Cruise Lamp: The scan tool displays On or Off. The requested state of the cruise indicator as commanded by the PCM. The BCM receives a class 2 message from the PCM. The IPC receives the illumination request from the BCM via the serial peripheral interface (SPI).

Division: The scan tool displays Chevrolet or Invalid. The IPC transmits the division to the BCM via the serial peripheral interface (SPI).

Door Ajar Lamp: The scan tool displays On or Off. The requested state of the door ajar indicator as commanded by the BCM.

ECT Sensor: The scan tool displays -40-151°C (-40-304°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 switch. An open switch with low engine oil level is displayed as Low.

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 with low engine oil pressure is displayed as Low.

Engine Speed: The scan tool displays 0-9999 RPM. Engine speed is computed by the PCM from the 3X reference input. It should remain close to desired idle under various engine loads with the engine idling.

English/Metric State: The scan tool displays English Units or Metric. The current unit of measurement used by the IPC.

Fuel Gage Position: The scan tool displays 0-255 counts. The BCM converts the fuel level percent class 2 message from the PCM into a gage position. The IPC receives the fuel gage position message from the BCM via the serial peripheral interface (SPI).

Fuel Tank Level Remaining: 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. The BCM receives a class 2 message from the PCM indicating the fuel level percent.

Gear Position: The scan tool displays Drive/Drive 1/Drive 2/Drive 3/Neutral/Reverse/Park. The IPC displays the gear position as determined by the PCM. The BCM sends the gear position to the IPC via the serial peripheral interface (SPI).

Generator Lamp: The scan tool displays On or Off. The requested state of the charging system indicator as commanded by the PCM. The BCM receives a class 2 message from the PCM requesting illumination.

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

High Coolant Temp Lamp: The scan tool displays On or Off. The requested state of the engine coolant temperature indicator as commanded by the PCM. The BCM receives a class 2 message from the PCM requesting illumination.

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

Low Coolant Lamp: The scan tool displays On or Off. The requested state of the low engine coolant indicator as commanded by the BCM.

Low Fuel Lamp: The scan displays On or Off. The requested state of the low fuel indicator as commanded by the BCM. The BCM determines when the low fuel indicator should illuminate based on the fuel level percent class 2 message from the PCM.

Low Oil Lamp: The scan tool displays On or Off. The requested state of the engine oil level indicator as commanded by the PCM. The BCM receives a class 2 message from the PCM requesting illumination.

Low Washer Lamp: The scan tool displays On or Off. The requested state of the low washer fluid indicator as commanded by the BCM.

Oil Pressure Lamp: The scan tool displays On or Off. The requested state of the engine oil pressure indicator as commanded by the PCM. The BCM receives a class 2 message from the PCM requesting illumination.

Park Lamp Input: The scan tool displays On or Off. The BCM monitors the headlamp switch. A closed switch with the headlamp switch in the park or head position is displayed as On.

Phase Lock Loop: The scan tool displays OK or Fault. The timing state of the serial peripheral interface (SPI).

Seat Belt Lamp: The scan tool displays On or Off. The requested state of the fasten safety belt indicator as commanded by the BCM.

Service Veh. Soon Lamp: The scan tool displays On or Off. The requested state of the service vehicle soon indicator as commanded by the BCM or PCM. The BCM receives a class 2 message from the PCM requesting illumination.

SPI Data Input: The scan tool displays High or Low. The state of the SPI serial data in circuit. The IPC transmits data to the BCM on this circuit.

SPI Data Output: The scan tool displays High or Low. The state of the SPI serial data out circuit. The BCM transmits data to the IPC on this circuit.

SPI Serial Data Status: The scan tool displays OK or Fault. That status of the serial peripheral interface (SPI).

Tach Signal: The scan tool displays Active or Inactive. The IPC monitors the voltage at the engine speed signal circuit (converted output from the PCM). The IPC sends a message to the BCM via the serial peripheral interface (SPI) indicating the status of the engine speed signal circuit.

Temp. Gage Position: The scan tool displays 0-255 counts. The BCM converts the engine coolant temperature class 2 message from the PCM into a gage position. The IPC receives the engine coolant temperature gage position message from the BCM via the serial peripheral interface (SPI).

Theft System Lamp: The scan tool displays On or Off. The requested state of the theft system indicator as commanded by the BCM.

VSS Signal: The scan tool displays Active or Inactive. The IPC monitors the voltage at the vehicle speed signal circuit (converted output from the PCM). The IPC sends a message to the BCM via the serial peripheral interface (SPI) indicating the status of the vehicle speed signal circuit.

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.