GM Service Manual Online
For 1990-2009 cars only

The Scan Tool Data Definitions list contains a brief description of all of the engine related parameters that are available on the scan tool. The list is arranged in alphabetical order. A given parameter may appear in any one of the data lists. In some cases the parameter may appear more than once, or in more than one data list in order to group certain related parameters together.

A/C High Side Pressure: This parameter displays the high side pressure of the A/C system based on the signal from the A/C high side pressure sensor calculated by the control module.

A/C High Side Pressure Sensor: This parameter displays the voltage from the A/C high side pressure sensor signal circuit to the control module.

A/C OFF for WOT: This parameter displays whether the control module is commanding the A/C compressor clutch relay off for wide open throttle (WOT).

A/C Pressure Disable: This parameter displays whether the A/C pressure is out of range for normal operation as determined by the control module.

A/C Relay Command: This parameter displays the state of the A/C clutch relay control circuit as commanded by the control module.

A/C Request: This parameter displays the state of the air conditioning (A/C) request input to the control module from the heating, ventilation, and air conditioning (HVAC) controls.

Air Fuel Ratio Bank 1 or Bank 2: This parameter displays the air fuel ratio as calculated by the control module for bank 1 or bank 2.

APP Angle: This parameter displays the angle of the accelerator pedal position (APP) as calculated by the control module using the signals from the APP sensors.

APP at Idle: This parameter displays the angle of the APP as calculated by the control module at idle using the signals from the APP sensors.

APP Sensor 1: This parameter displays the actual voltage on the APP sensor 1 signal circuit as measured by the control module.

APP Sensor 2: This parameter displays the actual voltage on the APP sensor 2 signal circuit as measured by the control module.

Battery Voltage: This parameter displays the battery voltage measured at the battery circuit of the control module.

Calculated Baro: This parameter displays the barometric pressure as calculated by the control module.

Calc. Converter Temp.: This parameter displays the catalytic converter temperature as calculated by the control module. Since this value is calculated the vehicle may need to be driven to provide enough information for the control module to calculate the temperature accurately.

Catalyst Overtemp Bn. 1: This parameter displays whether the catalytic converter for bank 1 is over operating temperature as calculated by the control module.

Catalyst Overtemp Bn. 2: This parameter displays whether the catalytic converter for bank 2 is over operating temperature as calculated by the control module.

Clutch Start Switch: This parameter displays the state of the clutch start switch input to the control module for a vehicle equipped with a manual transmission.

CMP Active Counter: This parameter displays an incrementing counter when the control module receives a signal from the camshaft position (CMP) sensor.

Cooling Fan After Run: This parameter displays whether the control module has activated the cooling fans based off of information received from the engine coolant temperature (ECT) sensor after key OFF.

Commanded Cooling Fan: This parameter displays whether the control module has activated the cooling fans based off of information received from the ECT sensor and HVAC system.

Crank Request: This parameter displays whether the ignition switch has been cycled to the crank position requesting the control module to activate the starter relay.

Cruise Clutch Switch : This parameter displays the state of the cruise/clutch pedal switch input to the control module for a vehicle equipped with a manual transmission.

Cruise Engaged: This parameter displays the status of the cruise control system as determined by the control module.

Cruise On/Off Switch: This parameter displays the state of the cruise control on/off switch input to the control module.

Cruise Release Brake Pedal Switch: This parameter displays the state of the brake pedal switch input to the control module.

Cruise Resume/Accel. Switch: This parameter displays the state of the cruise controls resume/accel switch input to the control module.

Cruise Set/Coast Switch: This parameter displays the state of the cruise controls set/coast switch input to the control module.

Cruise VSS Out of Range: This parameter displays whether the vehicle speed is out of the range to allow the cruise control to engage.

Current Gear: This parameter displays the transmission gear commanded by the control module. On a manual transmission the vehicle must be moving to display the gear that has been selected by the driver.

Decel. Fuel Cutoff: This parameter displays the status of the operating mode of the control module used to turn off the fuel injectors during certain deceleration conditions.

Delivered Torque PWM Duty Cycle: This parameter displays the duty cycle of the torque delivered from the engine as determined by the control module.

Desired Idle Speed: This parameter displays the desired engine idle speed in RPM commanded by the control module.

Distance Since First Failure: This parameter displays the distance traveled since the indicated DTC set in the control modules history.

DTC #1: This parameter displays the first diagnostic trouble code (DTC) set in the control modules history.

DTC #2: This parameter displays the second DTC set in the control modules history.

ECM in VTD Fail Enable VTD: This parameter displays whether an incorrect password has been received from the theft deterrent module on start up.

ECT: This parameter displays the temperature of the engine coolant based on input to the control module from the ECT sensor.

Engine At Operating Temperature: This parameter displays whether the engine has reached normal operating temperature as determined by the control module by information from the ECT sensor.

Engine Drag Control Active: This parameter displays whether the engine drag control is active as determined by the control module by information from the electronic brake control module (EBCM).

Engine Load: This parameter displays the calculated engine load in percent based on inputs to the control module from various engine sensors.

Engine Oil Life Remaining: This parameter displays the amount engine oil life remaining before requiring an oil change. This number is calculated by the control module based on inputs from various sensors.

Engine Oil Level Switch: This parameter displays the level of engine oil as determined by the control module from information received from the engine oil level switch.

Engine Oil Pressure Switch: This parameter displays the state of the engine oil pressure as determined by the control module from information received from the engine oil pressure switch.

Engine Run Time: This parameter displays the time elapsed since the engine was started.

Engine Speed: This parameter displays the speed of the engines crankshaft rotation from information received from the crankshaft position (CKP) sensor.

EVAP Canister Purge: This parameter displays the on-time or duty cycle of the EVAP canister purge solenoid commanded by the control module.

EVAP Vent Solenoid: This parameter displays the state of the driver circuit for EVAP vent solenoid as commanded by the control module.

Extended Travel Brake Pedal Switch: This parameter displays the state of the brake pedal as determined by the control module from the extended travel brake pedal switch position.

Fast Idle for A/C Performance: This parameter displays whether the control module has commanded a higher idle for improved A/C performance.

Fast Idle for Cold Start: This parameter displays whether the control module has commanded a higher idle to decrease engine warm up time.

Fast Idle for Generator Performance: This parameter displays whether the control module has commanded a higher idle for improved generator performance.

Fast Idle for Heater Performance: This parameter displays whether the control module has commanded a higher idle for improved heater performance.

Fast Idle for Hot Start: This parameter displays whether the control module has commanded a higher idle for improved engine cooling.

Fuel Level: This parameter displays the amount of fuel in the tank as determined by the control module from information received from the left and right fuel tank level senders.

Fuel Level Sensor Left Tank: This parameter displays the voltage signal received by the control module from the left fuel level sensor.

Fuel Level Sensor Right Tank: This parameter displays the voltage signal received by the control module from the right fuel level sensor.

Fuel Pump Relay Command: This parameter displays the control modules commanded state of the fuel pump relay.

Fuel Tank Pressure Sensor: This parameter displays the pressure/vacuum inside the fuel tank. A negative value indicates a vacuum, while a positive value indicates a pressure.

Fuel Tank Pressure Sensor: This parameter displays the voltage signal received by the control module from the fuel tank pressure (FTP) sensor.

GEN L-Terminal Signal Command: This parameter displays the control modules commanded state of the voltage regulator on the generator.

GEN F-Terminal Signal: This parameter displays the amount of generator on-time as commanded by the control module. The higher the percentage the greater the generator output.

HO2S Bank 1 or Bank 2 Sensor 1: This parameter displays the voltage output from the bank 1 or bank 2 sensor 1 heated oxygen sensor (HO2S) to the control module. Low voltage indicates a lean exhaust, while high voltage indicates a rich exhaust.

HO2S Bank 1 or Bank 2 Sensor 2: This parameter displays the voltage output from the bank 1 or bank 2 sensor 2 heated oxygen sensor (HO2S) to the control module. Low voltage indicates a lean exhaust, while high voltage indicates a rich exhaust.

HO2S Heater Bn 1 or Bn 2 Sen. 1: This parameter displays the commanded state of the bank 1 or bank 2 sensor 1 heater control circuit as commanded by the control module.

HO2S Heater Bn 1 or Bn 2 Sen. 2: This parameter displays the commanded state of the bank 1 or bank 2 sensor 2 heater control circuit as commanded by the control module.

HO2S Heater Bn 1 or Bn 2 Sen. 1: This parameter displays the commanded state of the bank 1 or bank 2 sensor 1 heater control circuit duty cycle as commanded by the control module.

HO2S Heater Bn 1 or Bn 2 Sen. 2: This parameter displays the commanded state of the bank 1 or bank 2 sensor 2 heater control circuit duty cycle as commanded by the control module.

IAT: This parameter displays the temperature of the intake air entering the air induction system based on input to the control module from the intake air temperature (IAT) sensor.

Ignition 0: This parameter displays the ignition 0 input voltage to the control module.

Ignition 1: This parameter displays the ignition 1 input voltage to the control module.

Ignition Dwell: This parameter displays the ignition coil saturation time as determined by the control module.

Ignition State: This parameter displays the position of the ignition switch based on the signal received by the control module.

Inj. PWM Average Bank 1: This parameter displays the average pulse width modulation (PWM) of the fuel injectors for bank 1 as determined by the control module.

Inj. PWM Average Bank 2: This parameter displays the average PWM of the fuel injectors for bank 2 as determined by the control module.

Intake Manifold Tuning (IMT) Valve Solenoid: This parameter displays the control modules commanded state of the intake manifold tuning (IMT) solenoid.

Intake Manifold Runner Control (IMRC) Solenoid: This parameter displays the control modules commanded state of the intake manifold runner control (IMRC) solenoid.

Knock Control: This parameters indicates whether the control module is adjusting the timing to alleviate excessive engine knock.

Knock Sensor 1: This parameters displays the voltage input to the control module from the knock sensor (KS) 1.

Knock Sensor 2: This parameters displays the voltage input to the control module from the KS 2 .

Knock Retard Cyl. 1-6: This parameter displays the knock retard as commanded by the control module for cylinders 1-6.

LT FT Bn. 1 or Bn. 2 Cruise/Accel.: This parameter displays the commanded Long Term Fuel Trim correction by the control module for bank 1 or bank 2 for cruise and acceleration conditions.

LT FT Bn. 1 or Bn. 2 Idle/Decel.: This parameter displays the commanded Long Term Fuel Trim correction by the control module for bank 1 or bank 2 for idle and deceleration conditions.

Loop Status Bank 1 or Bank 2: This parameter displays the state of the fuel control system for bank 1 or bank 2 as commanded by the control module. Closed Loop operation indicates that the control module is controlling the fuel delivery based off the oxygen sensors input voltage. In Open Loop operation the control module ignores the oxygen sensor input voltage and bases the amount of fuel to be delivered on other sensor inputs.

MAF: This parameter displays the measured quantity of air flowing into the engine during all operating conditions.

MAF Sensor: This parameter displays the signal voltage from the mass air flow (MAF) sensor to the control module.

Main Relay Command: This parameter displays the control modules commanded state of the engine main relay.

MIL: This parameter displays the commanded state of the malfunction indicator lamp (MIL) control circuit by the control module.

MIL Flashing: This parameter displays whether a catalyst damaging emissions failure has occurred and continued engine operation could damage the three-way catalyst.

Mileage Since DTC Cleared: This parameter displays the mileage that has elapsed since any DTC has been cleared from the control modules memory.

Mileage Since MIL Request: This parameter displays the mileage that has elapsed since the control module has commanded the MIL On.

Misfire Current Cyl. 1-6: The scan tool displays 0-255 counts. The display shows the number of misfires that have been detected during the last 200 cylinder firing events. The counters may normally display some activity, but the activity should be nearly equal for all of the cylinders, and in low numbers.

Misfire History Cyl. 1-6: This parameter displays the total level of misfire that has been detected on each cylinder.

Number of DTC(s): This parameter displays the actual quantity of DTCs that are stored in the controls modules memory.

Password Learning Enabled: This parameter displays whether the control module will enable learning of the first password that the vehicle theft deterrent (VTD) module sends to the control module on key up.

PNP Switch: This parameter displays whether the transmission range selector is in park or neutral.

Power Enrichment: This parameter displays the status of the operating mode of the control module used to increase fuel delivery during certain acceleration conditions.

Power Management (TAC Error): This parameter displays whether the control module is commanding engine power management due to a throttle actuation control (TAC) failure.

Rough Road Detection: This parameter displays whether the EBCM is detecting rough road conditions and transmitting this information to the ECM on the serial data circuit.

Reduced Power (TAC Error): This parameter displays whether the control module is commanding reduced engine power due to a TAC failure.

Requested Torque PWM Duty Cycle: This parameter displays the duty cycle of the torque requested by the EBCM from the engine control module.

Short Term FT Bank 1 or Bank 2: This parameter displays the short-term correction to the fuel delivery by the control module in response to the amount of time the oxygen sensor 1 spends above or below the 450 mV threshold. If the oxygen sensor voltage averages less than 450 mV, indicating a lean air/fuel mixture, the control module will add fuel increasing the short term fuel trim above 0. If the oxygen sensor voltage averages more than 450 mV, indicating a rich air/fuel mixture, the control module will reduce fuel decreasing the short term fuel trim below 0.

Spark Advance: This parameter displays the amount of spark advance the control module is commanding on the ignition control circuit. The control module determines the desired advance

Starter Relay Command: This parameter displays the control modules commanded state of the starter motor relay control circuit.

Start Up ECT: This parameter displays the temperature of the engine coolant on start up based on input to the control module from the ECT sensor.

Start Up IAT: This parameter displays the temperature of the intake air at start up entering the air induction system based on input to the control module from the IAT sensor.

Stoplamp Pedal Switch: This parameter displays the position of the stop lamp pedal switch input to the control module.

TAC Forced Engine Idle: This parameter displays whether the control module is commanding the engine to idle due to a TAC failure relating to inaccurate values from the APP sensors.

TAC Limit Power: This parameter displays whether the control module is commanding limited engine power due to a throttle actuation control (TAC) failure relating to TP sensor 1 circuit fault, a throttle actuator motor circuit fault or a concern with the TP Angle verses desired TP Desired Angle.

Throttle Actuator DC: This parameter displays the percentage of throttle actuator motor on time as commanded by the control module.

Throttle Plate at Idle: This parameter displays whether the throttle plate is in the idle position as commanded by the control module.

Throttle Plate at WOT: This parameter displays whether the throttle plate is in the wide open throttle (WOT) position as commanded by the control module.

TP 1 Learned Min: This parameter displays the learned minimum value of TP sensor 1 as recorded by the control module on start up for the ignition cycle.

TP 2 Learned Min: This parameter displays the learned minimum value of TP sensor 2 as recorded by the control module on start up for the ignition cycle.

TP Angle: This parameter displays the percent of throttle opening as calculated by the control module using information from the two throttle position (TP) sensors.

TP Desired Angle: This parameter displays the desired throttle position (TP) angle commanded by the control module.

TP Sensor 1: This parameter displays the actual voltage on the throttle position (TP) sensor 1 signal circuit as measured by the control module.

TP Sensor 2: This parameter displays the actual voltage on the throttle position (TP) sensor 2 signal circuit as measured by the control module.

Vehicle Speed: This parameter displays the speed of the vehicle as calculated by the control module from information received from the vehicle speed sensor (VSS).

Volumetric Efficiency: This parameter displays the calculated volumetric efficiency of the engine as calculated by the control module.