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 High Side Pressure Sensor: This parameter displays the voltage signal sent to the control module from the A/C high side pressure sensor. The A/C high side pressure sensor has a range of values indicating a low refrigerant pressure when the voltage is low to a high refrigerant pressure when the voltage is high. This parameter also displays kPa and psi.

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 air conditioning (A/C) request input to the control module from the heating, ventilation, and air conditioning (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 Flow Calculated: This parameter displays the air flow of the engine as calculated by the control module using information from the manifold absolute pressure (MAP) sensor. The scan tool will display a range of values indicating a high air flow when MAP pressure is high and low air flow when MAP pressure is low. This value is listed in grams per second (g/s).

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.

AIR Indicated Pressure: The normalized pressure is the filtered pressure minus the ambient air pressure measured by the sensor.

AIR Pressure Sensor: This parameter displays the unfiltered secondary air injection system pressure.

AIR Pressure Sensor: This parameter displays the secondary air injection system pressure analog input as a percentage of its reference voltage.

AIR Pressure Sensor Variance: This parameter displays the weighted average pressure error, difference between the predicted and actual secondary air injection system pressure, during the secondary air injection on test, phase 1.

AIR Pump Relay Circuit Status: This parameter displays the status of the output driver for the AIR pump relay control circuit. The scan tool will display OK if the circuit is operating correctly or Not Run if a diagnosis has not been made. The scan tool will display Fault if there is an open, short to ground, or a short to voltage in the circuit.

AIR Pump Relay Command: This parameter displays the commanded state of the secondary air injection pump. The states include ON or OFF.

AIR Solenoid Circuit Status: This parameter displays the status of the output driver for the AIR solenoid control circuit. The scan tool will display OK if the circuit is operating correctly or Not Run if a diagnosis has not been made. The scan tool will display Fault if there is an open, short to ground, or a short to voltage in the circuit.

AIR Solenoid Command: This parameter displays the commanded state of the secondary air injection valve. The states include ON or OFF.

APP Average: This parameter displays the average of the 3 accelerator pedal position (APP) sensors as calculated by the throttle actuator control (TAC) module. The APP average is a range of values indicating a low number when the accelerator pedal is not depressed to a high number when the accelerator pedal is fully depressed. This value is listed in counts.

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 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 accelerator pedal position (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 2: This parameter displays the voltage signal sent to the control module from accelerator pedal position (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 Sen. 1 and 2: This parameter displays the results of a control module test that compares the signals from the accelerator pedal position (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 accelerator pedal position. Disagree indicates that APP sensor 1 and APP sensor 2 voltages correspond to different accelerator pedal positions.

BARO: This parameter displays the barometric pressure 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 barometric pressure during wide-open throttle (WOT) conditions.

Cam Phase Angle Actual: The scan tool displays 0-25°. The scan tool will display the actual commanded cam degrees retard.

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

Cam Phase Angle Variance: The scan tool displays 0-25°. The scan tool will display the difference in degrees between the desired and actual cam angle.

Camshaft Phase Solenoid DC: The scan tool displays 0-100 percent. The scan tool will display in percentage the amount of cam phase retard .

CKP Active Counter: The crankshaft position (CKP) active counter displays whether the 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 Resync Counter: The camshaft position (CMP) resync counter displays the number of times the PCM had to resync with the CMP sensor.

Crank Request Signal: This parameter displays the state of the crank request input to the control module from the ignition switch. The scan tool will display Yes when the ignition switch is in the Crank position. The scan tool will display No when the ignition switch is in any other position.

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.

Cruise Disengage History 1-8: The Scan tool displays the last 8 cruise control disengages in order from 1 to 8. There are 20 possible causes for the cruise control to disengage.

Cruise On/Off Switch: The scan tool displays OFF/ON. When the cruise control module is enabled, the scan tool displays ON.

Cruise Release Clutch/TCC Pedal Switches--Range Applied/Released: When the brake pedal is applied, the torque converter clutch (TCC) brake switch sends a signal to the PCM to disengage the TCC and disable cruise control.

Cruise Resume/Accel Switch: This parameter displays the state of the Resume/Accel switch input to the control module 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 Switch: This parameter displays the state of the Set/Coast switch input to the control module from the cruise control system. 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 Fan Speed:  The PCM commands the desired fan speed. The PCM compensates for various engine loads based on engine coolant temperature in order to keep the fan at the desired speed.

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.

ECT Sensor: The scan tool displays a range of -40 to +151°C (-40 to +303°F). The powertrain control module (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 Oil Level Switch: This parameter displays the level of engine oil level as determined by the control module. The control module determines the level of the engine oil using the signal from a switch used to monitor the engine oil level. The control module uses this information to turn on the low engine oil lamp if the engine oil level remains below approximately 1 quart for a sufficient amount of time. The scan tool will display Low when the engine oil level is low. The scan tool will display OK when the engine oil level is correct.

Engine Oil Life Remaining: This parameter displays the amount of engine oil life remaining before requiring an oil change. This number is calculated by the control module based on many inputs and is displayed as a percent. The lower the percentage, the sooner the next oil change will be required.

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 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.

Engine Torque:  This display indicates the amount of available engine torque.

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 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.

Fan Speed: The scan tool displays the fan speed in RPM.

Fuel Level Sensor: This parameter displays the approximate fuel level 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 percentage when the fuel level in the tank is low or near empty. The scan tool will display a high percentage when the fuel level in the tank is high or near full.

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 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 in H2O).

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.

Generator F-Terminal Signal: The scan tool displays percentage.

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 powertrain control module (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.

Injector 1-6 Command: The scan tool displays 0-999.9 mS. Indicates the PCM command on the fuel injectors. The higher the number the longer the PCM is commanding the fuel injectors ON.

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 spark advance in response to the signal from the knock sensors.

Long Term FT: 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 throttle position (TP) sensor, engine coolant temperature (ECT) sensor inputs only.

MAP Sensor: The scan tool displays a range of 10-105 kPa and 0.00-5.0 volts. The manifold absolute pressure (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 crankshaft position (CKP) sensor.

MIL Command: This parameter displays the commanded state of the malfunction indicator lamp (MIL) control circuit. The malfunction indicator lamp should be on when the scan tool indicates the MIL Command is On. The malfunction indicator lamp 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 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 - #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.

Number Of DTC(s): This parameter indicates the total number of current diagnostic trouble codes (DTCs) set. These current DTCs set does not necessarily mean that the malfunction indicator lamp (MIL) is illuminated.

PCM/VCM in VTD Fail Enable: The PCM displays Yes or No. The scan tool displays Yes if the body control module (BCM) and the powertrain control module (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.

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 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 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 degrees to +64 degrees. The scan tool displays the amount of degrees the powertrain control module (PCM) commands the spark advance. 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 -40 to +151°C (-40 to +303°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).

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

TCC Enable Solenoid Command: This parameter displays the commanded state of the torque converter clutch (TCC) solenoid control circuit. The scan tool will display ON or OFF. ON indicates the TCC solenoid control circuit is being grounded by the control module, operating the torque converter. OFF indicates the TCC solenoid is not being commanded on by the control module.

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: This parameter displays the angle of the throttle position (TP) in percent. This information is calculated by the control module using the signals from the throttle position 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 throttle position (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 throttle position (TP) sensor 1 in percent. This information is calculated by the control module using the signal from the throttle position 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 throttle position (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 throttle position (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 throttle position (TP) sensor 2 in percent. This information is calculated by the control module using the signal from the throttle position 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.

TR Sw: The scan tool displays High/Low. A transaxle mounted switch is used as an input to let the PCM know what position the gear select lever is in. The scan tool status will switch from Park, Reverse, Neutral, Drive 4, Drive 3, Drive 2, Drive 1.

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.

VTD Fuel Disable: 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 Password: The scan tool displays OK, or Incorrect. This parameter indicates the validity of the vehicle theft deterrent password.

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 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.