GM Service Manual Online
For 1990-2009 cars only
Adjust Display Down Switch: The scan tool displays Inactive/Active. This is the state of the head up display (HUD) Information Down Switch.

Adjust Display Up Switch: The scan tool displays Inactive/Active. This is the state of the HUD Information Up Switch

Ambient Light Sensor: The scan tool displays the state of the ambient light sensor as determined by the HUD.

Auto. Trans. Equipped: The scan tool displays No/Yes. The scan tool displays if the vehicle is equipped with an automatic transmission system.

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

Battery Voltage Signal: The scan tool displays 0-19 volts. This is the voltage measured at the battery positive voltage circuit of the instrument panel cluster (IPC).

Brake Fluid: The scan tool displays Ok/Low. This is the status of the brake fluid level switch signal.

Brake Fluid Switch: The scan tool displays the voltage at the brake fluid switch signal circuit as monitored by the IPC.

Change Engine Oil Indicator Command: The scan tool displays Off/On. This is the state of the change engine oil indicator as determined by the IPC. The IPC receives a GMLAN message from the ECM indicating the engine oil life.

Commanded Gear: The scan tool displays the commanded gear as determined by the transmission control module (TCM).

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

Current Gear: The scan tool displays the current gear (P/N, 1st, 2nd, 3rd, 4th, 5th and Reverse) of the transmission.

Display Dimming: The scan tool displays 0-100%. This is the current state of the display dimming as controlled from the dimmer switch.

Display Dimming Signal: The scan tool displays Volts. The scan tool displays the voltage at the Display Dimming Signal circuit of the HUD.

ECT Sensor: The scan tool displays -40 to +151°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 Life Remaining: The scan tool displays 0-100%. The ECM calculates the amount of engine oil life remaining.

Engine Oil Level Switch: The scan tool displays OK or Low. The ECM monitors the engine oil level switch and receives a serial data message indicating the engine oil level.

Engine Oil Pressure Sensor: The scan tool displays OK or Low. The ECM monitors the engine oil pressure sensor and this is the engine oil pressure as monitored by the ECM

Engine Oil Pressure Sensor: The scan tool displays the oil pressure in kPa or psi. This is the engine oil pressure as monitored by the ECM.

Engine Oil Pressure Sensor: The scan tool displays 0-5 volts. The ECM monitors the engine oil pressure sensor and receives serial data message indicating the engine oil pressure sensor voltage.

Engine Oil Temperature Sensor: The scan tool displays °C (°F). The ECM monitors the engine oil temperature sensor and this is the engine oil temperature as monitored by the ECM.

Engine Oil Temperature Calculated: The scan tool displays °C (°F). The ECM monitors the engine oil temperature sensor and this is the engine oil temperature as calculated by the ECM.

Engine Speed: The scan tool displays 0-8000 RPM. Engine speed is computed by the ECM from the ignition reference input. It should remain close to desired idle under various engine loads with the engine idling.

Engine Speed Signal: The scan tool displays 0-8000 RPM. The engine speed is computed by the IPC from the engine speed serial data message from the ECM.

English Metric Status: The scan tool displays English or Metric system. This is the selected unit that is display in the HUD.

English/Metric Switch: The scan tool displays English or Metric system. This is the selected unit (English or Metric) that is displayed in the IPC.

Fuel Level Sensor Left Tank: The scan tool displays 0-5 volts. The ECM monitors the signal circuit of the secondary fuel level sensor.

Fuel Level Sensor Right Tank: The scan tool displays 0-5 volts. The ECM monitors the signal circuit of the primary fuel level sensor.

Fuel Tank Level Remaining: The scan tool displays 0 to 100% which is the approximate value of fuel remaining in the tank. The ECM calculates the amount of fuel remaining in the tanks based on the signal circuits of the fuel level sensors.

Fuel Tank Level Remaining: The scan tool displays the approximate value of fuel remaining in liters or gallons. The ECM calculates the amount of fuel remaining in the tanks based on the signal circuits of the fuel level sensors.

Gage Back Lighting Dimming: The scan tool displays 0 to 100 %. This is the status of the gage backlighting dimming as controlled from the switch.

Ignition 1 Signal: The scan tool displays 9-16 Volts. This is the voltage present at the Ignition 1 voltage circuit of the ECM.

Ignition 1 Input: The scan tool displays Inactive or Active. The scan tool displays Active when voltage is present at Ignition 1 input of the IPC.

Ignition Accessory Signal: The scan tool displays Off or On. This is the ignition accessory voltage as monitored by the ECM.

Ignition Cycle Counter: The scan tool displays Counts. The scan tool displays the number of times the ignition has been cycled as provided by the IPC.

Indicator Dimming: The scan tool displays 0-100%. The scan tool displays the current state of the indicator dimming as provided by the IPC.

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

Information Reset Switch: The scan tool displays Inactive or Active. This is the state of the Information Reset Switch of the DIC as provided by the IPC.

Information Up Switch: The scan tool displays Inactive or Active. This is the state of the Information Up Switch of the DIC as provided by the IPC

LCD Dimming: The scan tool displays 0-100%. The scan tool displays the current state of the LCD dimming as provided by the IPC.

Low EOP Indicator Command: The scan tool displays Off/On. This is the state of the low EOP indicator as determined by the IPC. The IPC receives a GMLAN message from the ECM indicating the engine oil pressure.

Low Engine Oil Level Indicator Command: The scan tool displays Off/On. This is the state of the low engine oil level indicator as determined by the IPC. The IPC receives a GMLAN message from the ECM indicating the engine oil pressure.

Malfunction Indicator Lamp (MIL) Circuit Status: The scan tool displays Fault. This is the status of the MIL circuit as monitored by the ECM.

MIL Command: The scan tool displays Off or On. The is the commanded state of the MIL by the ECM. The MIL should be on in the IPC when the scan tool displays the MIL Command is On.

Pointer Dimming: The scan tool displays 0-100%. The scan tool displays the current state of the pointer dimming as provided by the IPC.

PRNDL State: The scan tool displays Invalid, First Gear, Second Gear, Third Gear, Fourth Gear, Fifth Gear, Reverse, Neutral, Park, Drive, Not Available. The IPC displays the current transmission range as provided by the ECM. The IPC receives a serial data message indicating the vehicle transmission range from the TCM.

Reduced Engine Power: The scan tool displays Inactive or Active. This is the state of the Reduced Engine Power message as commanded by the ECM. The IPC receives a serial data message requesting the display of the Reduced Engine Power message.

Speed Biasing Status: The scan tool displays Disabled or Enabled. This is the status of the speed biasing feature as provided by the HUD.

Trip Odometer A/B Switch: The scan tool displays Inactive or Active. This is the status of the Trip Odometer A/B Switch as provided by the IPC. The trip odometer switch states can be toggled between trips A and B.

Trip Reset Switch: The scan tool displays Inactive or Active. This is the state of the odometer trip reset switch as provided by the IPC.

Vehicle Speed: The scan tool displays km/h or mph. The vehicle speed is computed by the IPC from the vehicle speed serial data message from the ECM.

Vehicle Speed Circuit Status: The scan tool displays Short Gnd/open, Incomplete, Open, short to B+ and Ok. Tis is the state of the vehicle speed circuit status as monitored by the ECM.

Vehicle Speed Sensor: The scan tool displays 0-255 km/h (0-155 mph). This is the vehicle speed as calculated by the ECM.

Vehicle Security Status: The scan tool display Fuel Continued, Disable Timeout, Disable Ign., Off Key Timer Active, VTD Fail Enable, Learn Enable. The scan tool displays the Vehicle Security Status as detected by the ECM.