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.

4WD Low Signal: The scan tool displays Enabled or Disabled. The transfer case should be in 4WD low when the scan tool displays Enabled.

4WD Signal: The scan tool displays Enabled or Disabled. The transfer case should be in 4WD when the scan tool displays Enabled.

A/C Compressor Cycling Switch: The scan tool displays Open or Closed. This parameter displays the state of the A/C compressor cycling switch. The A/C compressor cycling switch is a normally closed switch.

A/C Relay Command: The scan tool displays ON or OFF. This parameter displays the PCM commanded state of the A/C clutch control relay. When the scan tool displays ON, the A/C clutch should be engaged.

A/C Request Signal: The scan tool displays Yes or No. The A/C Request displays the state of the A/C request input circuit from the heating, ventilation, and air conditioning (HVAC) controls. The powertrain control module (PCM) uses the A/C request signal in order to determine whether the A/C compressor operation is being requested.

Air Fuel Ratio: The scan tool displays the ratio of the air to fuel. A typical ratio is about 14.7:1.

BARO: The scan tool displays a range of 10-105 kPa and 0.00-5.00 volts. The barometric pressure reading is determined from the manifold absolute pressure (MAP) sensor signal. The PCM monitors the MAP signal during key up or wide-open throttle (WOT) conditions. The barometric pressure compensates for altitude differences.

Brake Switch: The scan tool displays Applied or Released. This parameter indicates the state of the brake switch circuit input. The scan tool displays Applied when you apply the vehicle brakes. The scan tool displays Released when you release the vehicle brakes.

CMP Sensor High to Low: The scan tool displays 0-65,535 counts. The counts increment as the PCM detects the camshaft position (CMP) sensor signal voltage going from high to low.

CMP Sensor Low to High: The scan tool displays 0-65,535 counts. The counts increment as the PCM detects the CMP signal voltage going from low to high.

Clutch Pedal Switch: The scan tool displays Depressed or Released. The scan tool displays Depressed when you apply the vehicle clutch. The scan tool displays Released when you release the clutch pedal.

Cruise Control Active: The scan tool displays Yes/No. When the cruise control module is enabled, the scan tool displays Yes.

Cruise Inhibit Signal Command: The scan displays On or Off. On displayed indicates that the powertrain control module (PCM) is commanding the SMCC module to inhibit cruise control operation.

Current Gear: The scan tool displays 0-4. The scan tool displays which gear the transmission is in. An illegal transmission position displays 9.

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: The scan tool displays Active or Inactive. Active displayed indicates that the powertrain control module (PCM) has detected conditions appropriate to operate in Deceleration Fuel Cutoff Mode. The PCM will command Deceleration Fuel Cutoff Mode when a sudden decrease in throttle position (TP) has been detected while the vehicle is traveling over 40 km/h (25 mph). While in Deceleration Fuel Cutoff Mode, the PCM will decrease the amount of fuel delivered by entering Open Loop and decreasing the injector pulse width.

Desired IAC Airflow: The scan tool displays a range of 0-64 grams per second (g/s). This parameter displays a calculated airflow within the idle air control (IAC) passage.

Desired IAC Position: The scan tool displays a range of 0-255 counts. This parameter displays the desired IAC position as requested by the PCM.

Desired Idle Speed: The scan tool displays a range of 0-3,187 RPM. The PCM commands the desired idle speed. The PCM compensates for various engine loads based on ECT in order to keep the engine at the desired speed.

DTC Set This Ignition: The scan tool displays Yes or No. This parameter indicates if a diagnostic trouble code (DTC) set during the current ignition cycle.

ECT Sensor: The scan tool displays a range of -39°C to +140°C (-38°F to +284°F). The PCM applies 5.0 volts to the 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: The scan tool displays a range of 0-100 percent . The PCM calculates the engine load from engine speed and mass air flow (MAF) sensor readings. The engine load increases with an increase in RPM or airflow.

Engine Oil Life Remaining: The scan tool displays 0-100 percent . This display represents the engine oil life index that is calculated and maintained by the PCM.

Engine Oil Pressure Sensor: This parameter displays the voltage signal sent to the control module from the engine oil pressure sensor. The engine oil pressure sensor has a range of values indicating a low oil pressure when the voltage is low to a high oil pressure when the voltage is high.

Engine Run Time: The scan tool displays Hours, Minutes, Seconds. This displays the amount of engine run time for the current ignition cycle. When you cycle the ignition OFF, the timer resets to zero.

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 Purge Solenoid Command: The scan tool displays a range of 0 percent-100 percent. The PCM supplies a pulse width modulated (PWM) duty cycle to control the EVAP purge solenoid valve. 0 percent indicates no purge. 100 percent indicates full purge.

EVAP Test Result: The scan tool displays if the EVAP test has passed or failed. The scan tool displays pass when the PCM determines that the EVAP diagnostic has passed. The scan tool displays fail when the PCM determines that the EVAP diagnostic has failed.

EVAP Test State: The scan tool displays Wait for Purge, Test Running, Test Complete. This parameter indicates the state of the EVAP Service Bay Test.

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.

Fail Counter: The scan tool displays the number of times that a diagnostic has failed.

Fuel Level Sensor: The scan tool displays 0-5.00 volts. The scan tool displays below 1.0 volt for an empty tank, and close to 2.5 volts for a full tank.

Fuel Tank Level Remaining: The scan tool displays in liters or gallons the amount of fuel remaining in the fuel tank.

Fuel Tank Level Remaining: The scan tool displays 0-100 percent. The scan tool displays in percentage the amount of fuel remaining in the fuel tank.

Fuel Tank Pressure Sensor: The scan tool displays in -32.7 to +13.96 mm/Hg or -17.4 to +7.5 (in H2O). This parameter indicates the pressure vacuum inside of the fuel tank. A negative value indicates a vacuum. A positive value indicates a pressure.

Fuel Tank Pressure Sensor: The scan tool displays 0-5.0 volts. The scan tool displays in voltage the pressure inside of the fuel tank.

Fuel Tank Rated Capacity:  The scan tool displays the capacity of the fuel tank in liters or gallons.

Fuel Trim Cell: The scan tool displays a range of 0 to 23. The PCM determines from the manifold absolute pressure (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: The scan tool displays Enabled or Disabled. When conditions are appropriate for enabling long term fuel trim corrections, the scan tool displays 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.

Gen F-Terminal Signal: The scan tool displays Active or Inactive. The scan tool displays inactive if the PCM does not detect a correct voltage on the F-terminal circuit. The scan tool displays active under normal operating conditions.

Gen L- Terminal Signal: The scan tool displays ON or OFF. The scan tool displays OFF if the PCM does not detect a correct voltage on the L-terminal circuit. The scan tool displays ON under normal operating conditions.

HO2S Heater Bank 1 and Bank 2, Sensor 1 and Sensor 2: The scan tool displays the current in amps through the heaters. When the sensor is cool the start-up current will be high. As the sensor heats up the current will decrease and stabilize to a lower value.

HO2S Bank 1 Sensor 1: The scan tool displays a range of 0-1,106 mV. The heated oxygen sensor ( HO2S) bank 1 and bank 2 sensor 1 parameter represents the fuel control exhaust oxygen sensor output voltage. The voltage fluctuates constantly within a range between 10 mV, and 1,000 mV, while operating in Closed Loop.

HO2S Bank 1 Sensor 2: The scan tool displays a range of 0-1,106 mV. The heated oxygen sensor ( HO2S) bank 1 and bank 2 sensor 1 parameter represents the fuel control exhaust oxygen sensor output voltage. The voltage fluctuates constantly within a range between 10 mV, and 1,000 mV, while operating in Closed Loop.

IAC Position: The scan tool displays counts from 0 to 1,024. The counts represent the commanded idler air control (IAC) position by the PCM. The scan tool displays 0 counts for a fully seated IAC pintle. The counts increase as the idle increases. The counts vary depending on the load placed on the engine at idle.

IAT Sensor: The scan tool displays a range of -39°C to +140°C (-38°F to +284°F). The PCM converts the resistance of the intake air temperature 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: The scan tool displays 0-25.5 volts. The ignition 1 represents the system voltage measured by the PCM at the ignition feed circuit.

Injector PWM Bank 1 and Bank 2 Average: The scan tool displays a range of 0-1,000 milliseconds. The injector average indicates the amount of time the PCM commands each injector ON during each engine cycle. A longer injector pulse width causes more fuel to be delivered. The injector pulse width increases with an increased engine load.

Knock Retard: The scan tool displays a range of 0.0 degrees-16 degrees. Knock retard indicates the amount of spark the PCM removes from the ignition control (IC) spark advance in response to the signal from the knock sensors.

Long Term FT1 and FT2 Avg Bank 1 and Bank 2: The scan tool displays percentage. This parameter indicates the average of all long term fuel trim cells. The short term fuel trim cells are rated, for the amount of which they are used. For example, an idle cell is rated higher than a wide open cell. If a fueling malfunction occurs in the idle cell and the wide open cell, the average would be more affected by the idle cell than the wide open cell. A negative value significantly below 0 percent indicates that the fuel system is rich and fuel delivery is being reduced. A positive value significantly more than 0 percent indicates that a lean condition exists and the PCM compensates by adding fuel. When the average of the cells reach a predetermined high or low, a fuel trim DTC sets.

Long Term FT Bank 1 and Bank 2: 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.

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 throttle position (TP) sensor, engine coolant, and MAF sensor inputs only.

MAF Sensor: The scan tool displays a range of 0.0-655 g/s. The 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 Sensor: The scan tool displays a range of 0-31,999 Hz. The MAF sensor is a hot wire type air flow sensor. The PCM converts current draw needed by the MAF to keep the hot wires at a constant into a frequency signal. The scan tool displays this frequency in a hertz signal.

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.

MIL Command: The scan tool displays On or Off. The scan tool indicates if the PCM has commanded the malfunction indicator lamp (MIL) ON.

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

Mileage Since First Failure: The scan tool displays Kilometers or Miles. This parameter indicates the mileage accumulated since an emission diagnostic trouble code (DTC) first failed. The PCM stores this mileage in the Freeze Frame/Failure Records buffers.

Misfire Counter Status: The scan tool displays Normal or Invalid. The scan tool displays Normal if the PCM detects a true misfire. If the scan tool displays Invalid, the PCM is detecting a rough road condition, or any condition that caused an abnormal crankshaft speed other than a true misfire.

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.

Not Run Counter: The scan tool displays counts from 0-65,535. The scan tool displays the number of times a DTC diagnostic has not reached the predetermined criteria in order to run since the first DTC run failure.

Pass Counter: The scan tool displays counts from 0-65,535. The scan tool displays the number of times a DTC has passed.

PCM in VTD Fail Enable: The PCM displays Yes or No. The scan tool displays Yes if the body control module (BCM) and the PCM lose communications with each other after the BCM sends the correct password. The scan tool displays No if the BCM is communicating the correct password to the PCM.

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 or Inactive. An Active display indicates that the powertrain control module (PCM) has detected conditions appropriate to operate in Power Enrichment Mode. The PCM will command Power Enrichment Mode when a large increase in throttle position and load is detected. While in Power Enrichment, the PCM will increase the amount of fuel delivered by entering Open Loop and increasing the injector pulse width. This is done to prevent a possible sag or hesitation form occurring during acceleration.

SHRT Term FT Bn1 and Bn2: The scan tool displays percentage. This parameter indicates the average of the short term fuel trim cells. The short term fuel trim cells are rated for the amount of which they are used. For example, the PCM rates an idle cell higher than a wide open cell. If a fueling malfunction occurs in the idle cell and the wide open cell, the idle cell would affect more than then the wide open cell. 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 is compensating by adding fuel. When the average of the cells reach a predetermined high or low, a fuel trim DTC sets.

Short Term FT Bank 1 and Bank 2: 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.

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 on the IC circuit. The PCM computes the desired spark advance using the following: (1) engine coolant temperature (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 -39°C to +140°C (-38°F to +284°F). The scan tool displays the engine ECT at the time the engine was started. The PCM uses start-up ECT for certain DTCs.

TCC Brake Pedal Switch: The scan tool displays Applied or Released. This parameter indicates the state of the torque converter clutch/cruise control (TCC/CC) brake switch circuit input. Open indicates 0 voltage input, brake switch open, brake pedal applied. Closed indicates a B+ voltage input, brake switch closed, brake pedal released. When you apply the vehicle brakes, the scan tool displays Applied. The TCC/CC disengages. When you release the vehicle brakes, the scan tool displays Released. This allows the CC to be resumed and the TCC to engage.

TCC Enable Solenoid Command: The scan tool displays ON or OFF. The scan tool displays ON when the electrical system supplies a voltage to the TCC enable solenoid .

TCC PWM Solenoid Command: The scan tool displays ON or OFF. This parameter is the commanded state of the (TCC) PWM solenoid. The scan tool displays ON when the commanded state of the solenoid is ON. The scan tool displays OFF when the solenoid is OFF.

TFP SW: The scan tool displays the transmission gear position.

Torque Delivered Signal: The scan tool displays ft or lbs. Represents the pulse width modulation (PWM) signal which indicates the percent of available torque the engine is delivering to the drive wheels. The electronic brake/traction control module (EBCM) monitors the Traction Control Torque signal to ensure that the powertrain control module (PCM) is responding properly to the Traction Control Desired Torque signal.

Torque Request Signal: The scan tool displays ft or lbs. Represents the pulse width modulation (PWM) signal from the electronic brake and traction control module. The electronic brake/traction control module (EBCM) reduces the traction control desired torque signal pulse width when a drive wheel slippage situation is detected. The powertrain control module (PCM) monitors the traction control desired torque signal and reduces drive wheel slippage as necessary by retarding spark timing, decreasing boost solenoid 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. A problem with the Traction Control Desired Torque signal should cause DTC P1571 to set.

TP Sensor: The scan tool displays 0-100 percent. The scan tool displays the amount of throttle opening in percentage. The scan tool displays about 0 percent at closed throttle. The scan tool displays about 100 percent at wide open throttle (WOT).

TP Sensor: The scan tool displays 0-5 volts. The scan tool displays the amount of throttle opening in voltage. When the throttle is at a closed throttle the voltage is between 0.4-0.9 volts. When the throttle is at WOT the voltage is above 4.0 volts.

TR Switch: The scan tool displays the transmission gear position.

Transmission OSS: The scan tool displays the transmission output shaft speed in RPM. The output speed sensor (OSS) provides the input signal.

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.

VTD Auto Learn Timer: The scan tool displays Active/Inactive. The auto learn timer is the indication if the vehicle theft deterrent (VTD) system is in the learn mode and has not timed out.

VTD Fuel Disable: The scan tool displays Active/Inactive. If the PCM has not received the correct password from the BCM, the PCM disables the fuel system and the scan tool displays Active. The scan tool displays Inactive under normal operating conditions.

VTD Fuel Disable Until Ignition Off: The scan tool displays Yes or No. With the ignition ON and a VTD code present, the scan tool displays Yes.

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.

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 information with a scan tool or a loss of power to the PCM also resets the counter to 0.