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 Clutch Feedback Signal: The scan tool displays Yes or No. This parameter displays the signal received from the A/C clutch to the powertrain control module (PCM) to indicate the A/C clutch is ON or OFF.

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 powertrain control module (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 Sec. High Press. Switch: The scan tool displays Open or Closed. This parameter displays the state of the A/C secondary high pressure switch. The A/C secondary high pressure switch is normally open.

A/C Request: 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.

AIR Pump Relay Command: The scan tool displays ON or OFF. The scan tool displays ON when the powertrain control module (PCM) grounds the secondary air injection (AIR) pump relay control circuit. The scan tool displays OFF when the PCM disables the ground circuit.

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

Brake Pedal Switch: The scan tool displays Applied or Release. This parameter displays the state of the brake pedal.

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

Coolant Level Switch: The scan tool displays Yes or No. This parameter indicates when the engine coolant level is low. The scan tool displays Yes when the powertrain control module (PCM) detects the engine coolant level is low.

Cruise On/Off Switch: The scan tool displays On or Off. When you activate the cruise control switch, 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 you turn OFF the cruise control switch, the scan tool displays OFF.

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 displays ON. When the Resume/Accel switch is released the scan tool displays 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 displays ON. When the Set/Coast switch is released the scan tool displays OFF.

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 powertrain control module (PCM) counts the number of misfire tests during 200 engine revolutions.

Desired EGR Position : The scan tool displays 0-100 percent . This parameter displays the desired position of the exhaust gas recirculation (EGR) pintle as requested by the powertrain control module (PCM). This parameter should be very close to actual EGR position.

Desired EGR Position: The scan tool displays 0-5.0 volts. The commanded exhaust gas recirculation (EGR) is the EGR pintle position commanded by the powertrain control module (PCM).

Desired Idle Speed: The scan tool displays a range of 0-3,187 RPM. The powertrain control module (PCM) commands the desired idle speed. The PCM compensates for various engine loads based on engine coolant temperature (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.

EGR Learned Minimum POS: The scan tool displays 0-5.0 volts. This display represents the voltage that the powertrain control module (PCM) uses in order to determine whether or not the exhaust gas recirculation (EGR) valve is closed. The voltage displayed will be the closed position of the EGR pintle learned by the PCM.

EGR Position Sensor: The scan tool displays 0-5.0 volts. This parameter displays the actual EGR pintle position in voltage.

EGR Position Sensor: The scan tool displays a range of 0-100 percent. The powertrain control module (PCM) supplies a pulse width modulated (PWM) duty cycle to control the exhaust gas recirculation (EGR) valve. Zero percent indicates no EGR flow. One hundred percent indicates full EGR flow.

Engine Load: The scan tool displays a range of 0-100 percent . The powertrain control module (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 Level Switch: The scan tool displays Yes or No. This parameter indicates when the engine oil level is low. The scan tool displays Yes when the powertrain control module (PCM) detects the engine oil level is low.

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 powertrain control module (PCM).

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

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

EVAP Test Result: The scan tool displays if the evaporative emission (EVAP) test has passed or failed. The scan tool displays pass when the powertrain control module (PCM) determines that the EVAP diagnostic has passed. The scan tool displays fail when the PCM determines that the EVAP diagnostic has failed.

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: 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 0-23. The powertrain control module (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.

Generator L Terminal Signal Command: The scan tool displays Active or Inactive. The scan tool displays inactive if the powertrain control module (PCM) does not detect a correct voltage on the L-terminal circuit. The scan tool displays active under normal operating conditions.

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

IAT Sensor: The scan tool displays a range of -39°C to +140°C (-38°F to +284°F). The powertrain control module (PCM) converts the resistance of the intake air temperature sensor to degrees. The PCM uses the intake air temperature (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 powertrain control module (PCM) at the ignition feed circuit.

Inj. PWM Average Bank 1 and Bank 2: The scan tool displays a range of 0-1,000 milliseconds. The injector average indicates the amount of time the powertrain control module (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 0-16 degrees. Knock retard indicates the amount of spark the powertrain control module (PCM) removes from the ignition control (IC) spark advance in response to the signal from the knock sensors (KS).

Long Term FT Ave Bn1 and Bn2: 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 powertrain control module (PCM) compensates by adding fuel. When the average of the cells reach a predetermined high or low, a fuel trim diagnostic trouble code (DTC) sets.

Long Term FT Bank 1 and Bank 2: The scan tool displays percentage. The powertrain control module (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 powertrain control module (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 the throttle position (TP) sensor, engine coolant, and mass air flow (MAF) sensor inputs only.

Low Oil Lamp Command: The scan tool displays On or Off. The scan tool displays On when the powertrain control module (PCM) detects that there is a low oil level condition. The low oil lamp is then commanded ON by the PCM.

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 mass air flow (MAF) sensor is a hot wire type air flow sensor. The powertrain control module (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/0.0-5 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, the intake vacuum decreases resulting in a higher MAP sensor voltage and kPa reading. The powertrain control module (PCM) uses the MAP sensor signal for the following: (1) Updating the barometric pressure (BARO) reading; (2) Enabling factor for several of the diagnostics.

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

Misfire Current Cyl. #1 - #8: 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 powertrain control module (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 - #8: 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 diagnostic trouble code (DTC) has not reached the predetermined criteria in order to run since the first failure.

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

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

PCM/VCM in VTD Fail Enable: The powertrain control module (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.

PNP Switch: The scan tool displays the gear shift lever position.

Short Term FT Ave 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 powertrain control module (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 diagnostic trouble code (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 powertrain control module (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 to +64 degrees. The scan tool displays the amount of degrees the powertrain control module (PCM) commands the spark advance on the ignition control (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 to +140°C (-38 to +284°F). The scan tool displays the engine coolant temperature (ECT) at the time the engine was started. The powertrain control module (PCM) uses start-up ECT for certain diagnostic trouble codes (DTCs).

Stoplamp Pedal 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.

TCC Brake Pedal Switch: The scan tool displays Applied or Released. This parameter indicates the state of the torque converter clutch (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 torque converter clutch and cruise control disengages. When you release the vehicle brakes, the scan tool displays Released. This allows the cruise control to be resumed and the torque converter clutch to engage.

TCC Enable Solenoid Command: The scan tool displays Enabled or Disabled. The scan tool displays Enabled when the electrical system supplies a voltage to the torque converter clutch (TCC) enable solenoid .

TCC PWM Solenoid Command: The scan tool displays 0-100 percent. This parameter is the commanded state of the (TCC) pulse width modulation (PWM) solenoid. The scan tool displays 100 percent when the commanded state of the solenoid is ON. The scan tool displays 0 percent when the solenoid is OFF.

TP Desired Angle: The scan tool displays 0-100 percent. The powertrain control module (PCM) indicates the desired throttle angle commanded by the vehicle operator.

TP Indicated Angle: The scan tool displays 0-100 percent. The throttle position (TP) Indicated Angle displays in percentage the amount of throttle opening.

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

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

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

Vehicle Speed Sensor: The scan tool displays km/h and mph. The vehicle speed sensor (VSS) 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 Disabled: The scan tool displays Active/Inactive. If the powertrain control module (PCM) has not received the correct password from the body control module (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 vehicle theft deterrent (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 powertrain control module (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 powertrain control module (PCM) also resets the counter to 0.