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 Status: The scan tool displays On or Off. The scan tool will display On when voltage is applied to the A/C compressor clutch.

Actual EGR Position: The scan tool range is 0-100 percent. The actual EGR position indicates the actual EGR position in a percentage.

APP Average: The scan tool displays 0 to 125 counts. The TAC module takes the voltages from the 3 APP sensors, averages them, and converts them into steps. This average is displayed on the scan tool. The average will be different on every vehicle.

APP Indicated Angle: The scan tool displays 0-100 percent. The scan tool will display accelerator pedal position in percentage. When the APP is at rest, display will show 0 percent. when the APP is fully depressed, display will show 100 percent.

APP Sensor 1 and APP Sensor 2 Disagree: The scan tool displays Yes or No. When the TAC Module receives a signal voltage from APP Sensor 1 not in proper relationship to APP Sensor 2, the scan tool will display Yes. The scan tool will display No under normal operating conditions.

APP Sensor 1 and APP Sensor 3 Disagree: The scan tool displays Yes or No. When the TAC Module receives a signal voltage from APP Sensor 1 not in proper relationship to APP Sensor 3, the scan tool will display Yes. The scan tool will display No under normal operating conditions.

APP Sensor 2 and APP Sensor 3 Disagree: The scan tool displays Yes or No. When the TAC Module receives a signal voltage from APP Sensor 2 not in proper relationship to APP Sensor 3, the scan tool will display Yes. The scan tool will display No under normal operating conditions.

APP Sensor 1 Out of Range: The scan tool displays Yes or No. If the APP Sensor voltage is not within specifications, the scan tool will display Yes. If the APP Sensor voltage is within specifications, the scan tool will display No.

APP Sensor 2 Out of Range: The scan tool displays Yes or No. If the APP Sensor voltage is not within specifications, the scan tool will display Yes. If the APP Sensor voltage is within specifications, the scan tool will display No.

APP Sensor 3 Out of Range: The scan tool displays Yes or No. If the APP Sensor voltage is not within specifications, the scan tool will display Yes. If the APP Sensor voltage is within specifications, the scan tool will display No.

APP Sensor 1: The scan tool displays 0-5.0 volts. When the accelerator pedal is at 0 percent (pedal at rest), display will show less than 1 volt. When the accelerator pedal is at 100 percent (pedal fully depressed), display will show more than 3.3 volts.

APP Sensor 2: The scan tool displays 5.0-0 volts. When the accelerator pedal is at 0 percent (pedal at rest), display will show more than 4 volts. When accelerator pedal is at 100 percent (pedal fully depressed), display will show less than 1 volt.

APP Sensor 3: The scan tool displays 5.0-0 volts. When the accelerator pedal is at 0 percent (pedal at rest), display will show more than 3.5 volts. When the accelerator pedal is at 100 percent (pedal fully depressed), display will show less than 2.6 volts.

APP Sensor 1 Angle: The scan tool displays 0-100 percent. When the accelerator pedal is at rest, display will show 0 percent. When the accelerator pedal is fully depressed, display will show 100 percent. This percentage indicates actual pedal position to the TAC Module.

APP Sensor 2 Angle: The scan tool displays 0-100 percent. When the accelerator pedal is at rest, display will show 0 percent. When the accelerator pedal is fully depressed, display will show 100 percent. This percentage indicates actual pedal position to the TAC Module.

APP Sensor 3 Angle: The scan tool displays 0-100 percent. When the accelerator pedal is at rest, display will show 0 percent. When the accelerator pedal is fully depressed, display will show 100 percent. This percentage indicates actual pedal position to the TAC Module.

BARO: The scan tool range is 10-105 kPa. The barometric pressure reading is determined from the MAP sensor signal monitored during key up and wide open throttle (WOT) conditions. The barometric pressure is used to compensate for altitude differences.

BARO: The scan tool range is 0.00-5.0 volts. The barometric pressure reading is determined from the MAP sensor signal monitored during key up and wide open throttle (WOT) conditions. The barometric pressure is used to compensate for altitude differences.

CAM Signal Input-Low to High: The scan tool displays 0-65535 counts. The counts increment as the PCM detects the camshaft sensor signal voltage going from low to high.

CAM Signal Input-High to Low: The scan tool displays 0-65535 counts. The counts increment as the PCM detects the camshaft sensor signal voltage going from high to low.

CC Brake Switch: The scan tool displays Applied or Released. This parameter indicates the state of the CC brake switch circuit input. An open switch indicates 0.0 voltage input (brake switch open, brake pedal applied). A closed switch indicates a B+ voltage input (brake switch closed, brake pedal released). When the vehicle brakes are applied, the scan tool display will show Applied. The torque converter clutch and cruise control will disengage. When the vehicle brakes are released, the scan tool will display Released. This will allow cruise control to be resumed and the torque converter clutch to engage.

Clutch Switch: The scan tool displays Depressed or Released. When the vehicle clutch pedal is depressed the scan tool display shows Depressed and the cruise control will disengage. When the vehicle clutch pedal is released the scan tool display shows Released, and the cruise control can be resumed.

Commanded EGR: The scan tool range is 0-100 percent. The scan tool display represents the PCM commanded PWM duty cycle of the exhaust gas recirculation (EGR) valve. 0 percent displayed indicates no EGR. 100 percent displayed indicates full EGR.

Cruise Switch: The scan tool displays On or Off. When the cruise control switch is activated, the scan tool displays On. The switch, when in the ON position, sends a signal voltage to the throttle actuator control (TAC) module. This allows all other functions of the cruise control. When the cruise control switch is turned OFF, the scan tool will display Off.

Cruise Requested: The scan tool displays Yes or No. When the cruise control switch is in the ON position and the Set/Coast switch is activated the scan tool will display Yes. When the cruise control switch is in the ON position and the Set/Coast switch is released the scan tool will display No.

Cruise Resume/Accel: The scan tool displays On or Off. When the cruise control switch is in the ON position and the Resume/Accel switch is activated, the scan tool will display On. When the Resume/Accel switch is released the scan tool will display Off.

Cruise Set/Coast: The scan tool displays On or Off. When the cruise control switch is in the ON position and the Set/Coast switch is activated, the scan tool will display On. When the Set/Coast switch is released the scan tool will display Off.

Cruise Disengage History 1-8: The scan tool will display the last 8 cruise control disengages in order from 1 to 8. There are 20 possible causes for the cruise control to disengage. Refer to Cruise Control Diagnosis

Desired Idle Speed: The scan tool range is 0-3187 RPM. The desired idle is the idle speed that is commanded by the PCM. The PCM will compensate for various engine loads based on engine coolant temperature to keep the engine at the desired speed.

Desired EGR Position: The scan tool range is 0-199.9 percent. The desired EGR position indicates the desired EGR position in a percentage.

DTC Set This Ignition: The scan tool displays Yes or No. This parameter indicates whether or not a diagnostic trouble code has been set on the current ignition cycle.

ECT: The scan tool range is -39°C-140°C (-38°F-284°F). The Engine Coolant Temperature (ECT) sensor is mounted in the cylinder head of the left bank. The PCM applies 5 volts to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as temperature changes. When the sensor is cold (internal resistance high), the PCM monitors a high signal voltage and interprets it as a cold engine. As the sensor warms (internal resistance decreases), the voltage signal will decrease and the PCM will interpret the lower voltage as a warm engine.

EGR Feedback: The scan tool range is 0.00-5.0 volts. The display indicates the EGR pintle position sensor signal voltage being monitored by the PCM. A low voltage indicates a fully extended pintle (closed valve). A voltage near 5 volts indicates a fully retracted pintle (open valve).

EGR Closed Pintle Position: The scan tool range is 0.00-5.0 volts. The display represents the learned voltage that the PCM uses to determine whether or not the EGR valve is fully closed (0 percent pintle position). If the EGR PWM is 0 percent and a difference of more than 0.4 volt between EGR feedback and EGR closed valve pintle position is detected, a DTC will set.

Engine Oil Pressure: The scan tool displays 0-144 psi 992 kPa. The scan tool displays engine oil pressure.

Engine Oil Life Remaining: The scan tool displays 0-100 percent. The scan tool displays the percent of oil life remaining. The PCM calculates the Engine Oil Life by monitoring engine load, engine temperature, and engine speed, etc.

EOP Sensor: The scan tool displays 0-5.0 volts. The scan tool displays engine oil pressure in volts.

Engine Run Time: The scan tool displays Hours, Minutes, and Seconds. This indicates the amount of time the engine has been operating. When the ignition is cycled OFF, the timer will be set to zero.

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

EVAP Canister Purge: The scan tool range is 0-100 percent. The display represents the PCM commanded PWM duty cycle of the EVAP purge solenoid valve. 0 percent displayed indicates no purge. 100 percent displayed indicates full purge.

Fuel Trim Cell: The scan tool range is 0-22 cell. The fuel trim cell is dependent upon the engine speed and the MAP sensor readings (a plot of the RPM vs the MAP sensor readings). A plot of the RPM vs the MAP is broken into 22 cells. The fuel trim cell indicates which cell is currently active.

Fuel Trim Diagnostic Inhibit: The scan tool displays Enabled/Disabled. The fuel trim diagnostic inhibit indicates the state of the fuel trim (Enabled/Disabled) that the PCM is commanding. Fuel trim will be disabled when the vehicle is not in Closed Loop. DTC(s) related to fuel trim are set and diagnostics that temporarily effect fuel trim operation are active.

Fuel Trim Learn: The scan tool displays Enabled or Disabled. When conditions are appropriate for enabling long term fuel trim corrections, the scan tool will display Enabled. This indicates that the long term fuel trim is responding to the short term fuel trim. If the scan tool displays Disabled, then long term fuel trim will not respond to changes in short term fuel trim.

HO2S Bank 1 Sensor 1: The scan tool range is 0-1000 mV. The scan tool display represents the fuel control exhaust oxygen sensor output voltage. The voltage should fluctuate constantly within a range between 10 mV (lean exhaust), and 1000 mV (rich exhaust), while operating in closed loop.

HO2S Bank 2 Sensor 1: The scan tool range is 0-1000 mV. The scan tool display represents the fuel control exhaust oxygen sensor output voltage. The voltage should fluctuate constantly within a range between 10 mV (lean exhaust), and 1000 mV (rich exhaust), while operating in closed loop.

IAT Sensor:  The scan tool range is -39°C-140°C (-38°F-284°F). The PCM converts the resistance of the intake air temperature (IAT) sensor to degrees. Intake air temperature is used by the PCM to adjust fuel delivery and spark timing according to incoming air density.

Ignition 1: The scan tool displays 0-25.5 volts. This represents the system voltage measured by the PCM at its ignition feed.

Injector PWM Average Bank 1: The scan tool range is 0-100 milliseconds. This range indicates the amount of time the PCM is commanding each injector ON during each engine cycle. A longer injector pulse width will cause more fuel to be delivered. Injector pulse width should increase with increased engine load.

Injector PWM Average Bank 2: The scan tool range is 0-1000 milliseconds. This range indicates the amount of time the PCM is commanding each injector ON during each engine cycle. A longer injector pulse width will cause more fuel to be delivered. Injector pulse width should increase with increased engine load.

Knock Retard: The scan tool range is 0.0°-16°. The display indicates the amount of spark the PCM is removing from IC spark advance in response to the signal from the knock sensors.

Knock Signal Present: The scan tool displays Yes or No. The display indicates whether or not a knock signal is being detected by the PCM. The display should read No at idle.

Long Term FT Bank 1: The scan tool range is 0-255 counts. The long term fuel trim (FT) is derived from the short term fuel trim value. The PCM uses the long term fuel trim for the long term correction of the fuel delivery. A value of 128 counts (0 percent) indicates that the fuel delivery requires no compensation to maintain a 14.7:1 air to fuel ratio. A value below 128 counts means that the fuel system is too rich and the fuel delivery is being reduced, decreased injector pulse width. A value above 128 counts indicates that a lean condition exists. The PCM compensates by adding fuel, increased injector pulse width.

Long Term FT Bank 2: The scan tool range is 0-255 counts. The long term fuel trim (FT) is derived from the short term fuel trim value. The PCM uses the long term fuel trim for the long term correction of the fuel delivery. A value of 128 counts (0 percent) indicates that the fuel delivery requires no compensation to maintain a 14.7:1 air to fuel ratio. A value below 128 counts means that the fuel system is too rich and the fuel delivery is being reduced, decreased injector pulse width. A value above 128 counts indicates that a lean condition exists. The PCM compensates by adding fuel, increased injector pulse width.

Long Term FT Bank 1: The scan tool displays percentage. Long term fuel trim is derived from the short term fuel trim value and represents a long term correction of fuel delivery. A value of 0 percent/128 indicates that fuel delivery requires no compensation to maintain the PCM commanded air/fuel ratio. A negative value significantly below 0 percent indicates that the fuel system is rich and fuel delivery is being reduced (decreased injector pulse width). A positive value significantly greater than 0 percent/128 indicates that a lean condition exists and the PCM is compensating by adding fuel (increased injector pulse width). Because long term fuel trim tends to follow short term fuel trim, a value in the negative range due to canister purge at idle should not be considered unusual. Fuel trim values at maximum authority may indicate an excessively rich or lean system.

Long Term FT Bank 2: The scan tool displays percentage. Long term fuel trim is derived from the short term fuel trim value and represents a long term correction of fuel delivery. A value of 0 percent/128 indicates that fuel delivery requires no compensation to maintain the PCM commanded air/fuel ratio. A negative value significantly below 0 percent indicates that the fuel system is rich and fuel delivery is being reduced (decreased injector pulse width). A positive value significantly greater than 0 percent/128 indicates that a lean condition exists and the PCM is compensating by adding fuel (increased injector pulse width). Because long term fuel trim tends to follow short term fuel trim, a value in the negative range due to canister purge at idle should not be considered unusual. Fuel trim values at maximum authority may indicate an excessively rich or lean system.

Loop Status: The scan tool displays Open or Closed. Closed Loop 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 TP sensor, engine coolant, and MAF sensor inputs only.

MAF: The scan tool range is 0.0-655 grams per second. Mass air flow (MAF) is the MAF input frequency converted to grams of air per second. This indicates the amount of air entering the engine.

MAF Frequency: The scan tool displays 0-31999 Hz. The PCM converts current draw needed by the MAF (to keep wires at a constant temperature) into a frequency signal. This frequency is displayed on the scan tool in Hertz.

MAP: The scan tool range is 10-105 kPa. The manifold absolute pressure (MAP) sensor measures the change in the intake manifold pressure from engine load and speed changes. As intake manifold pressure increases, intake vacuum decreases resulting in a higher MAP sensor voltage and kPa reading. The MAP sensor signal is used for the following: (1) To update the BARO reading, (2) Enabling factor for several of the diagnostics.

MAP: The scan tool range is 0.00 to 5.0 volts. The manifold absolute pressure (MAP) sensor measures the change in the intake manifold pressure from engine load and speed changes. As intake manifold pressure increases, intake vacuum decreases resulting in a higher MAP sensor voltage and kPa reading. The MAP sensor signal is used for the following: (1) To update the BARO reading, (2) Enabling factor for several of the diagnostics.

MIL: The scan tool displays On or Off. The scan tool will indicate if the PCM has commanded the malfunction indicator light (MIL) to be ON.

Mileage Since DTC Cleared: The scan tool displays Km or Miles. This parameter indicates the mileage accumulated since an emission diagnostic trouble code cleared. This mileage will be stored in the Freeze Frame and Failure record's buffers.

Park/Neutral: The scan tool displays Park/Neutral. The scan tool displays the position the gear shift lever is in.

PCM Reset: The scan tool displays Yes or No. This parameter indicates when an internal PCM reset has occurred. The scan tool will display Yes when an internal PCM reset occurs. The scan tool would display No under normal operating conditions.

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

Short Term FT Bank 1: The scan tool displays counts. 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 has mainly remained less than 450 mV, indicating a lean air/fuel mixture, short term fuel trim will increase above 128 and the PCM will add fuel. If the oxygen sensor voltage stays mainly above the threshold, short term fuel trim will decrease below 128 while the PCM reduces fuel delivery to compensate for the indicated rich condition. Under certain conditions such as extended idle and high ambient temperatures, canister purge may cause short term fuel trim to read low during normal operation. Fuel trim values at maximum authority may indicate an excessively rich or lean system.

Short Term FT Bank 2: The scan tool displays counts. 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 has mainly remained less than 450 mV, indicating a lean air/fuel mixture, short term fuel trim will increase above 128 and the PCM will add fuel. If the oxygen sensor voltage stays mainly above the threshold, short term fuel trim will decrease below 128 while the PCM reduces fuel delivery to compensate for the indicated rich condition. Under certain conditions such as extended idle and high ambient temperatures, canister purge may cause short term fuel trim to read low during normal operation. Fuel trim values at maximum authority may indicate an excessively rich or lean system.

Short Term FT Bank 1: The scan tool displays percentage. 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 has mainly remained less then 450 mV, indicating a lean air/fuel mixture, short term fuel trim will increase into the positive range above 0 percent/128 and the PCM will add fuel. If the oxygen sensor voltage stays mainly above the threshold, short term fuel trim will decrease below 0 percent/128 into the negative range while the PCM reduces fuel delivery to compensate for the indicated rich condition. Under certain conditions such as extended idle and high ambient temperatures, canister purge may cause short term fuel trim to read in the negative range during normal operation. Fuel trim values at maximum authority may indicate an excessively rich or lean system.

Short Term FT Bank 2: The scan tool displays percentage. 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 has mainly remained less then 450 mV, indicating a lean air/fuel mixture, short term fuel trim will increase into the positive range above 0 percent/128 and the PCM will add fuel. If the oxygen sensor voltage stays mainly above the threshold, short term fuel trim will decrease below 0 percent/128 into the negative range while the PCM reduces fuel delivery to compensate for the indicated rich condition. Under certain conditions such as extended idle and high ambient temperatures, canister purge may cause short term fuel trim to read in the negative range during normal operation. Fuel trim values at maximum authority may indicate an excessively rich or lean system.

Spark: The scan tool range is -64° to 64°. The scan tool displays the amount of spark advance being commanded by the PCM on the IC circuit. The PCM computes the desired spark advance using the following: (1) Engine coolant temperature, (2) Engine speed (RPM), (3) Load, and (4) Vehicle speed. All timing adjustments are completed by the PCM.

Startup ECT: The scan tool range is -39°C- 140°C (-38°F-284°F). When the engine is started, the PCM records the engine coolant temperature. The PCM uses the recorded temperature in order to calculate the time to a closed loop.

TAC/PCM Communication: The scan tool displays OK or Fault. If communication between the TAC module and the PCM is interrupted, the scan tool will display Fault. The scan tool will display OK under normal operating conditions.

TP Desired Angle: The scan tool displays 0-100 percent. The PCM will indicate desired throttle angle for conditions present at that time.

TP Indicated Angle: The scan tool displays 0-100 percent. TP indicates to the PCM in percentage, the amount of throttle opening.

TP Sensor 1: The scan tool displays 0-5 volts. The scan tool will display the amount of throttle opening in volts. Closed throttle will display 1 volt and wide open throttle will display 3.5 volts.

TP Sensor 2: The scan tool displays 5-0 volts. The scan tool will display the amount of throttle opening in volts. Closed throttle will display 4 volts and wide open throttle will display 1.5 volts.

TP Sensor 1 Angle: The scan tool displays 0-100 percent. The scan tool will display the amount of throttle opening in percentage. Closed throttle will display 0 percent and wide open throttle will display 100 percent.

TP Sensor 2 Angle: The scan tool displays 0-100 percent. The scan tool will display the amount of throttle opening in percentage. Closed throttle will display 0 percent and wide open throttle will display 100 percent.

TP Sensor 1 Out of Range: The scan tool displays Yes or No. If the PCM detects that the voltage is below 1 volt at closed throttle or above 3.5 volts at wide open throttle, the scan tool will display Yes. If the voltages are within specifications, the scan tool will display No.

TP Sensor 2 Out of Range: The scan tool displays Yes or No. If the PCM detects that the voltage is above 4 volts at closed throttle or below 1.5 volts at wide open throttle, the scan tool will display Yes. If the voltages are within specifications, the scan tool will display No.

TP Sensors Disagree: The scan tool displays Yes or No. When the TAC Module receives a signal voltage from one of the throttle position sensors not in proper relationship to the other, the scan tool will display Yes. The scan tool will display No under normal operating conditions.

Vehicle Speed: The scan tool displays 0-255 km/h (0-158 mph). The vehicle speed sensor signal is converted into km/h and mph for display.

Warm-Ups w/o Non-Emission Faults: The scan tool range is 0-255 count. This parameter counts the number of warm up cycles without a non-emission fault present. The counter will increment to 255 and roll back to 0 unless a fault occurs. If a fault occurs, the counter will revert back to 0 until the fault is corrected. Clearing information with a scan tool or a loss of power to the PCM will also reset the counter to 0.