The Engine Scan Tool Data Definitions contains a brief description of all engine related parameters available on the scan tool. The list is 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 Relay Command: This parameter displays the commanded state of the air conditioning (A/C) clutch relay control circuit. The scan tool will display ON or OFF. ON indicates that the A/C clutch relay control circuit is being grounded by the control module, allowing voltage to the A/C compressor clutch. OFF indicates that the A/C clutch relay is not being commanded ON by the control module.

A/C Request Signal: This parameter displays the state of the A/C request input to the control module from the HVAC controls. The scan tool will display Yes or No. Yes indicates that the control module is receiving a request from the HVAC system to ground the A/C clutch relay control circuit, engaging the A/C compressor clutch. No indicates that the control module is not receiving a request from the HVAC system to ground the A/C clutch relay control circuit.

Air Fuel Ratio: This parameter displays the ratio of air to fuel as calculated by the control module based on various sensor inputs. The scan tool will display a lower air fuel ratio when a richer air to fuel mixture is commanded. The scan tool will display a higher air fuel ratio when a leaner air to fuel mixture is commanded. In Closed Loop operation the air fuel ratio should normally be 14.2-14.7 to 1.

APP Indicated Angle: This parameter displays the angle of the accelerator pedal as calculated by the control module using the signals from the accelerator pedal position (APP) sensors. The APP indicated angle is a range of values indicating a low percentage when the accelerator pedal is not depressed to a high percentage when the accelerator pedal is fully depressed.

APP Sensor 1: This parameter displays the voltage signal sent to the control module from APP sensor 1 of the APP sensor assembly. APP sensor 1 is a range of values indicating a low voltage when the accelerator pedal is not depressed to a high voltage when the accelerator pedal is fully depressed.

APP Sensor 1 Circuit: This parameter displays the diagnostic state of the APP sensor 1 circuit. The scan tool will display OK or Fault. OK indicates that no circuit faults are detected during the current test. Fault indicates that a short or open circuit/component exists.

APP Sen. 1 and 2: This parameter displays the results of a control module test that compares the signals from the APP sensors 1 and 2 . The scan tool will display Agree or Disagree. Agree indicates that APP sensor 1 and APP sensor 2 voltages correspond to the same APP. Disagree indicates that APP sensor 1 and APP sensor 2 voltages correspond to different APPs.

APP Sensor 2: This parameter displays the voltage signal sent to the control module from APP sensor 2 of the APP sensor assembly. The APP sensor 2 is a range of values indicating a high voltage when the accelerator pedal is not depressed to a low voltage when the accelerator pedal is fully depressed.

APP Sensor 2 Circuit: This parameter displays the diagnostic state of the APP sensor 2 circuit. The scan tool will display OK or Fault. OK indicates that no circuit faults are detected during the current test. Fault indicates that a short or open circuit/component exists.

BARO: This parameter displays the barometric pressure (BARO) as calculated by the control module using the signal from the manifold absolute pressure (MAP) sensor measured when the ignition is turned ON with the engine not running. The control module will update the BARO during wide-open throttle (WOT) conditions.

Cam Phase Angle Desired: The scan tool displays 0-25°. The scan tool will display the desired cam phase angle.

Catalytic Converter Protection Active: This parameter displays the state of the Catalytic Converter Protection mode.

CKP Active Counter: The crankshaft position (CKP) active counter displays whether the powertrain control module (PCM) is receiving the pulses from the CKP sensor.

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

CMP Sensor: This parameter displays the speed of the engine as calculated by the signal from the CMP sensor.

Cruise Control Active: This parameter displays the status of the cruise control system as determined by the control module. The scan tool will display Yes when the cruise control system is in control of vehicle speed. The scan tool will display No when the cruise control system is not operating.

Cycles of Misfire Data: The scan tool displays a range of 0-100. The PCM counts the number of misfire tests during 200 engine revolutions.

Decel. Fuel Cutoff: This parameter displays the status of the operating mode used to turn off the fuel injectors during certain deceleration conditions. When the can tool displays Active, the control module has turned off the fuel injectors. When the scan tool displays Inactive, the fuel system is operating normally.

Desired Idle Speed: This parameter displays the engine idle speed in RPM commanded by the control module. The control module compensates for various engine loads in order to maintain the desired engine RPM at idle. This parameter is not valid unless the engine is running.

EC Ignition Relay Circuit Status: This parameter displays the status of the output driver for the engine control (EC) ignition relay control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground or a short to voltage on the circuit.

ECT Sensor: The scan tool displays a range of -40 to +151°C (-40 to +303°F). The PCM applies 5 volts to the engine coolant temperature (ECT) sensor circuit. The sensor is a thermistor which changes internal resistance as the engine temperature changes. When the sensor is cold, internal resistance high, the PCM senses a high signal voltage and interprets the voltage as a cold engine. As the sensor warms, internal resistance decreases, the voltage signal decreases and the PCM interprets the lower voltage as a warm engine.

Engine Load: This parameter displays the engine load in percent based on inputs to the control module from various engine sensors. The scan tool will display a low percentage when the engine is at idle with little or no load. The scan tool will display a high percentage when the engine is running at a high RPM under a heavy load.

Engine Off Time: This parameter displays the time elapsed since the engine was shut off.

Engine Oil Pressure Switch: This parameter displays OK or low.

Engine Run Time: This parameter displays the time elapsed since the engine was started. The scan tool will display the time in hours, minutes and seconds. The engine run time will reset to zero as soon as the engine stops running.

Engine Speed: The scan tool displays a range of 0-10,000 RPM. The PCM computes engine speed from the ignition reference pulses. The engine speed should remain close to desired idle under various engine loads with the engine idling.

EVAP Fault History: This parameter displays the result of the EVAP System diagnostic. The scan tool displays NO FAULT, EXCESS VACUUM, PURGE VALVE LEAK, SMALL LEAK, or WEAK VACUUM. The EVAP Fault History indicates the status of EVAP system diagnostics performed by the PCM.

EVAP Purge Solenoid Command: This parameter displays the on-time or duty cycle of the evaporative emission (EVAP) purge solenoid commanded by the control module expressed as a percent. The scan tool will display a high percentage when the control module is commanding the EVAP purge solenoid to be open a large amount . The scan tool will display a low percentage when the control module is commanding the EVAP purge solenoid to be open a small amount. The scan tool will display 0 when the control module is commanding the EVAP purge solenoid closed.

EVAP Vent Solenoid Command: The scan tool displays Venting or Not Venting. The EVAP canister vent valve is normally open. The PCM commands the EVAP canister vent valve closed, during testing of the EVAP system.

Fuel Pump Relay Command: This parameter displays the commanded state of the fuel pump relay control circuit. The scan tool will display ON or OFF. ON indicates the fuel pump relay control circuit is being grounded by the control module, allowing voltage to the fuel pump. OFF indicates the fuel pump relay is not being commanded on by the control module.

Fuel Tank Level Remaining: This parameter displays the amount of fuel remaining in the fuel tank as a percentage. The control module calculates this level using the signal from the sensor used to monitor the fuel level in the fuel tank. The scan tool will display a low reading when the fuel level in the tank is low or near empty. The scan tool will display a high reading when the fuel level in the tank is high or near full.

Fuel Tank Pressure Sensor: This parameter displays the voltage signal sent to the control module from the sensor used to monitor the pressure inside the fuel tank. The scan tool will display a low voltage when the pressure in the fuel tank is high. The scan tool will display a high voltage when the pressure in the fuel tank is low or in a vacuum.

Fuel Tank Pressure Sensor: The scan tool displays mm/Hg and in H2O vacuum or pressure. The scan tool displays a range of -32.7 to +13.96 mm/Hg (-17.4 to +7.5 inches H2O).

Fuel Trim Cell: The scan tool displays a range of 0-23. The PCM determines from the MAP and RPM inputs which fuel trim cell to operate the engine in. The fuel trim cell displayed on the scan tool is the cell that the engine is operating under.

Fuel Trim Learn: This parameter indicates if the control module is adjusting long term fuel trim in response to the short term fuel trim. The scan tool displays Enabled or Disabled. When conditions are appropriate form enabling long term fuel trim corrections, the scan tool displays Enabled.

Generator L-Terminal Signal Command: The scan tool displays OFF/ON.

HO2S 1: The scan tool displays a range of 0-1,106 mV.

HO2S 2: The scan tool displays a range of 0-1,106 mV.

HO2S 1 Heater Current: This parameter displays the current through the control module when the HO2S 1 heater is commanded ON by the control module. HO2S 1 Heater Current is a range of values indicating a low current when the heater circuit resistance is high to a high current when the heater circuit resistance is low.

HO2S 2 Heater Current: This parameter displays the current through the control module when the HO2S 2 heater is commanded ON by the control module. HO2S 2 Heater Current is a range of values indicating a low current when the heater circuit resistance is high to a high current when the heater circuit resistance is low.

IAT Sensor: The scan tool displays a range of -40 to +151°C (-40 to +303°F). The PCM converts the resistance of the intake air temperature (IAT) sensor to degrees. The PCM uses the IAT in order to adjust fuel delivery and spark timing according to incoming air density.

Ignition 1 Signal: This parameter displays the voltage measured at the ignition 1 circuit of the control module. Voltage is applied to the control module when the ignition switch is in the ignition 1 position.

Injector PWM: The scan tool displays 0-999.9 mS. Indicates the base pulse width modulation (PWM) or ON time of the fuel injectors in milliseconds. When the engine load is increased, the injector pulse width will increase.

Knock Retard: The scan tool displays a range of 0-16 degrees. Knock retard indicates the amount of spark the PCM removes from the spark advance in response to the signal from the knock sensors.

Long Term FT: The scan tool displays percentage. The PCM derives the long term fuel trim from the short term fuel trim value. The long term fuel trim represents a long term correction of fuel delivery. A value of 0 percent indicates that fuel delivery requires no compensation in order to maintain the PCM commanded air/fuel ratio. A negative value significantly below 0 percent indicates that the fuel system is rich and the PCM is reducing the fuel delivery. A positive value significantly more than 0 percent indicates that a lean condition exists and the PCM compensates by adding fuel. Fuel trim values at maximum authority indicates an excessively rich or lean system.

Mileage Since DTC Cleared: The scan tool displays Kilometers or Miles. This parameter indicates the mileage accumulated since an emission diagnostic trouble code (DTC) cleared. The PCM stores this mileage in the Freeze Frame and Failure Records memory.

Short Term FT Avg.: The scan tool displays %. This parameter is the average long term fuel trim for this bank as calculated by the control module. The scan tool will display a value more than 0 percent indicating that time is being added to the injector pulse width, increasing the amount of fuel to this bank of the engine. The scan tool will display a value of less than 0, indicating time is being subtracted from the injector pulse width, reducing the amount of fuel to this bank of the engine. A value of 0 percent indicates no compensation is required to operate the engine at the desired air/fuel ratio.

Loop Status: The scan tool displays Open or Closed. Closed Loop (CL) indicates that the PCM is controlling fuel delivery according to oxygen sensor voltage. In Open Loop, the PCM ignores the oxygen sensor voltage and bases the amount of fuel to be delivered on throttle position (TP) sensor, ECT sensor inputs only.

MAP Sensor: The scan tool displays a range of 10-105 kPa and 0.00-5.0 volts. The MAP sensor measures the absolute pressure in the intake manifold.

Medium Resolution Resync Counter: The scan tool displays 0-255 counts. The medium resolution resync counter displays the number of times the PCM had to resync the CKP sensor.

MIL Command: This parameter displays the commanded state of the malfunction indicator lamp (MIL) control circuit. The MIL should be on when the scan tool indicates the MIL Command is On. The MIL should be off when the scan tool indicates the MIL Command is Off. The control module will command the MIL On when the ignition is ON with the engine OFF in order to perform a bulb check.

Misfire Current Cyl. #1 - #6: The scan tool displays a range of 0-255 counts. The misfire current counters increment at a rate according to the number of possible misfires the PCM detects on each cylinder during the last 200 cylinder firing events. The counters may normally display some activity, but the activity should be nearly equal for all the cylinders.

Misfire History Cyl. #1 - #6: The scan tool displays a range of 0-65,535 counts. The misfire history counters display the total level of misfire that has been detected on each cylinder. The misfire history counters will not update or show any activity until a misfire DTC P0300 has become active. The misfire history counters will update every 200 cylinder firing events.

PCM Reset: The scan tool displays Yes or No. This parameter indicates when the internal PCM resets. The scan tool displays YES when an internal PCM reset occurred. The scan tool displays NO under the normal operating conditions.

Power Enrichment: The scan tool displays Active/Inactive. The scan tool indicates when power enrichment mode is active (moderate to heavy acceleration). Helpful in diagnosing DTC P1171.

Reduced Engine Power: The scan tool displays Active or Inactive. The scan tool displays Active when the PCM receives a signal from the throttle actuator control (TAC) module that a throttle actuator control system fault is occurring. The PCM limits the engine power.

Short Term FT: The scan tool displays percentage. The short term fuel trim represents a short term correction to fuel delivery by the PCM in response to the amount of time the fuel control oxygen sensor voltage spends above or below the 450 mV threshold. If the oxygen sensor voltage mainly remains less than 450 mV, indicating a lean air/fuel mixture, short term fuel trim increases into the positive range above 0 percent. The PCM adds fuel. If the oxygen sensor voltage stays mainly above the threshold, the short term fuel trim decreases below 0 percent into the negative range. The PCM reduces the fuel delivery in order to compensate for the indicated rich condition. Under certain conditions such as an extended idle and a high ambient temperature, the canister purge may cause the short term fuel trim to read in the negative range during normal operation. The fuel trim values at maximum authority may indicate an excessively rich or lean system.

Short Term FT Avg.: The scan tool displays %. This parameter indicates the average short term fuel trim for this bank. The scan tool will display a value more than 0 if the time is being added to the injector pulse width, increasing the amount of fuel to that bank of the engine to compensate for a lean condition sensed by the oxygen sensors on that bank. The scan tool will display a value less than 0 if time is being subtracted from the injector pulse width, reducing the amount of fuel to the engine to compensate for a rich condition sensed by the oxygen sensors on that bank. A value of 0 percent indicates no compensation is required to operate the engine at the desired air/fuel ratio.

Spark: The scan tool displays a range of -64 degrees to +64 degrees. The scan tool displays the amount of degrees the PCM commands the spark advance. The PCM computes the desired spark advance using the following: 1. ECT 2. Engine speed (RPM), 3. Load 4. Vehicle speed The PCM adjusts the timing.

Start Up ECT: The scan tool displays a range of -40 to +151°C (-40 to +303°F). The scan tool displays the ECT at the time the engine was started. The PCM uses start-up ECT for certain DTCs.

Start Up IAT: Indicated the IAT at the time that the vehicle was started. Used to determine if the last startup was a cold start. The scan tool range is -40 to +15°C (-40 to +302°F). This parameter indicates the ambient air temperature (AAT) at start-up.

Starter Enable Relay Circuit History: This parameter displays the status of the output driver for the starter enable relay control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground, or a short to voltage on the circuit.

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

Torque Delivered Signal: The scan tool range is 0-100 percent. Represents the PWM signal which indicates the percent of available torque the engine is delivering to the drive wheels. The electronic brake and traction control module (EBTCM) monitors the traction control torque signal to ensure that the PCM is responding properly to the traction control desired torque signal.

Torque Request Signal: The scan tool range is 0-100 percent. Represents the PWM signal from the EBTCM. The EBTCM reduces the traction control desired torque signal pulse width when a drive wheel slippage situation is detected. The PCM monitors the traction control desired torque signal and reduces drive wheel slippage as necessary by retarding spark timing, decreasing boost sol. PWM, or increasing air/fuel ratio. The PCM can also turn OFF up to three fuel injectors if the traction control desired torque signal indicates a large enough amount of drive wheel slippage.

Total Misfire Count: The scan tool range is 0-255 counts. This parameter indicates the total level of misfire that has been detected on each cylinder. The misfire history counters will not update or show any activity until a misfire or DTC P0300 has become active. The misfire history counter will update every 200 cylinder firing events.

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 Desired Angle: The scan tool displays 0-100 percent. The PCM indicates the desired throttle angle commanded by the vehicle operator.

TP Indicated Angle: This parameter displays the angle of the TP in percent. This information is calculated by the control module using the signals from the TP sensors. The scan tool will display a low percentage when the throttle plate is closed. The scan tool will display a high percentage when the throttle plate is fully open.

TP Sensor 1: This parameter displays the voltage signal sent to the control module from the sensor used to monitor the position of the throttle plate. This parameter is for sensor 1 of the TP sensor assembly. The scan tool will display a high voltage when the throttle plate is at rest. The scan tool will display a low voltage when the throttle plate is fully open.

TP Sensor  1: This parameter displays the angle of the TP sensor 1 in percent. This information is calculated by the control module using the signal from the TP sensor 1. The scan tool will display a low percentage when the throttle plate is closed. The scan tool will display a high percentage when the throttle plate is fully open.

TP Sensors 1 and 2: This parameter displays the results of a control module test that compares the signals from the TP sensors 1 and 2 . The scan tool will display Agree when the signal from TP sensor 1 corresponds with the signal from TP sensor 2. The scan tool will display Disagree when the signal from TP sensor 1 conflicts with the signal from TP sensor 2.

TP Sensor 2: This parameter displays the voltage signal sent to the control module from the sensor used to monitor the position of the throttle plate. This parameter is for sensor 2 of the TP sensor assembly. The scan tool will display a low voltage when the throttle plate is at rest. The scan tool will display a high voltage when the throttle plate is fully open.

TP Sensor 2: This parameter displays the angle of the TP sensor 2 in percent. This information is calculated by the control module using the signal from the TP sensor 2. The scan tool will display a low percentage when the throttle plate is closed. The scan tool will display a high percentage when the throttle plate is fully open.

Traction Control Signal: The scan tool displays Active/Inactive. This parameter indicates the status of the traction control system (TCS).

Traction Control Status: This parameter displays the status of the traction control circuit. The scan tool displays active if the PCM receives a signal from the EBTCM requesting torque reduction during a traction control event.

TWC Temperature Calculated: Represents the calculated temperature of the catalytic converter. Useful for determining if the Catalyst Monitor Test has run.

Vehicle Speed Sensor: The scan tool displays km/h and mph. The vehicle speed sensor signal is converted into km/h and mph for display on the scan tool.

Warm-ups w/o Emission Faults: The scan tool displays a range of 0-255. This parameter counts the number of warm-up cycles without an emission fault present. The counter increments to 255 and rolls back to 0 unless a fault occurs. If a fault occurs, the counter reverts back to 0 until the fault is corrected. Clearing the information with a scan tool or a loss of power to the PCM also resets the counter to 0. The scan tool displays counts. This display indicates the number of warm-up cycles without a emission failure.

Warm-ups w/o Non-Emission Faults: The scan tool displays a range of 0-255. This parameter counts the number of warm-up cycles without a non-emission fault present. The counter increments to 255 and rolls back to 0 unless a fault occurs. If a fault occurs, the counter reverts back to 0 until the fault is corrected. Clearing the information with a scan tool or a loss of power to the PCM also resets the counter to 0.