A list of each data message displayed on the Scan tool will be explained in two groups: Engine or Transmission. This information will assist in emission or driveability problems. The displays can be viewed while the vehicle is being driven. Always perform the Engine Controls Diagnostic System Check first. The Diagnostic System Check will confirm proper system operation.

A/C Compressor--Range Engaged/Disengaged: Indicates whether or not the air conditioning (A/C) compressor is engaged. The output test function in the scan tool can only be activated with the key ON, and the engine OFF.

A/C Relay--Range Disabled/Enabled: Represents the commanded state of the air conditioning (A/C) clutch control relay. The A/C clutch should be engaged with ON displayed.

A/C Request--Range ON/OFF: Represents the state of the air conditioning (A/C) request input from the control head.

Act. Inj. Timing--Range 0-25.0 Degrees: Current actual injection timing.

APP Angle--Range 0-100 Percent: Computed by the powertrain control module (PCM) from accelerator pedal position (APP) module voltage, or the throttle position, and should display 0 percent at idle and 100 percent at wide open throttle.

APP 1--Range 0-5 Volts: The powertrain control module (PCM) uses the accelerator pedal position (APP) sensors to control fuel delivery as requested by the driver. Three APP sensors are located in a module at the base of the accelerator pedal. The PCM only requires information from one sensor, the other two serve as fail-safes. APP 1 should read approximately 0.35-0.95 volts at idle to above 4 volts at wide open throttle (WOT).

APP 2--Range 0-5 Volts: The powertrain control module (PCM) uses the accelerator pedal position (APP) sensors to control fuel delivery as requested by the driver. Three APP sensors are located in a module at the base of the accelerator pedal. The PCM only requires information from one sensor, the other two serve as fail safes. APP 2 should read approximately 4.5 volts at idle and should steadily decrease to approximately 1 volt at wide open throttle.

APP 3--Range 0-5 Volts: The powertrain control module (PCM) uses the accelerator pedal position (APP) sensors in order to control the fuel delivery as requested by the driver. Three APP sensors are located in a module at the base of the accelerator pedal. The PCM only requires information from one sensor. The other two sensors serve as fail safes. APP 3 should read approximately 4 volts at idle and should steadily decrease to approximately 2.5 volts at wide open throttle.

BARO--Range 10-105 kPa: The barometric pressure (BARO) reading is determined from the boost sensor at ignition ON, engine OFF. The BARO reading display represents barometric pressure and is used to compensate for altitude differences.

Boost Pressure--Range 10-200 kPa, 0-5 Volts: The amount of turbo boost pressure in the intake manifold. This is measured in kPa and volts. True boost pressure is determined by subtracting the barometric pressure (BARO) from the actual reading.

Brake Switch--Range Open/Closed: Is used for stop lamps and a redundant cruise control disengagement switch.

Calc. A/C Load--Range: The amount of load the air conditioning (A/C) is putting on the engine.

Crank Reference Missed--Range 0-8: The scan tool will display the number of crank pulses missed. At idle, the crank reference missed range should read 0.

Cruise Active--Range ON/OFF: Indicates if the vehicle is in cruise control.

Cruise Brake Switch--Range Open/Closed: When the brake pedal is applied, the switch sends a signal to the powertrain control module (PCM) to disengage the cruise control.

Cruise Switch--Range ON/OFF: Indicates if the cruise switch on the turn signal lever is in the ON position.

Desired Idle--Range 0-3187 RPM: The idle speed that is requested by the powertrain control module (PCM). The PCM will compensate for various engine loads based on engine coolant temperature (ECT) to keep the engine at the desired speed.

Des. Inj. Timing--Range 0-25.5 Degrees: The amount of injection timing requested by the powertrain control module (PCM).

DTC Set This Ignition--Range #: Indicates the total number of current DTCs set this ignition cycle.

ECT--Range -40 to +151°C (-40 to +304°F): The engine coolant temperature (ECT) sensor sends a signal to the powertrain control module (PCM) relative to the engine coolant temperature. The sensor is a thermistor which changes the internal resistance as the temperature changes. When the sensor is cold and the internal resistance is high, the PCM monitors and interprets a high signal voltage as a cold engine. As the sensor warms and the internal resistance decreases, the voltage signal will decrease and the PCM will interpret the lower voltage as a warm engine.

ECT Sensor--Range 0-5 Volts: The engine coolant temperature (ECT) sensor sends a signal to the powertrain control module (PCM) relative to the engine coolant temperature. The sensor is a thermistor which changes internal resistance as temperature changes. When the sensor is cold and the internal resistance is high, the PCM monitors and interprets a high signal voltage as a cold engine. As the sensor warms and the internal resistance decreases, the voltage signal will decrease and the PCM will interpret the lower voltage as a warm engine.

Engine Load--Range 0-100 Percent: The amount of load on the engine.

Engine Run Time--Range 00:00:00 (HRS/MIN/SEC): A measure of how long the engine has been operating. When the ignition is cycled to OFF, the value is reset to zero.

Engine Shut-off Sol.--Range ON/OFF: The engine shut-off solenoid (ESO) is located on the fuel injection pump. When the ignition switch is OFF, the ESO is in the NO FUEL position. The ESO prevents fuel from entering the fuel injection pump.

Engine Speed--Range 0-9999 RPM: The engine speed is computed by the powertrain control module (PCM) from the crankshaft position sensor. If the crankshaft position (CKP) sensor is inoperative, an RPM reading is taken from the injection pump cam signal. The RPM reading should remain close to the desired idle during various engine loads with engine idling. The engine speed value is very accurate.

Engine Torque--Range 0-999 ft/lb: The amount of engine torque.

Fail Counter--Range (Decimal): The number of ignition cycles that a test has run and failed at least once.

First Odometer--Range Miles: The amount of miles in 3 mile increments that the vehicle has traveled since the Freeze Frame/Failure Record has been stored.

Freeze Frame and Failure Record Data Definitions: The Freeze Frame/Failure Record data list consists of as many of the same parameters as in an Engine data list. The list below defines the parameters that are not found in an Engine data list.

Fuel Rate--Range 0-80 mm3: This reading is displayed in millimeters cubed (mm3). This is the amount of fuel the powertrain control module (PCM) is requesting.

Fuel Temperature--Range -28 to +140°C (-18 to +285°F): There is a thermistor located in the optical sensor that determines fuel temperature. When the sensor is cold and the internal resistance is high, the powertrain control module (PCM) monitors and interprets a high signal voltage as low fuel temperature. As the sensor warms and the internal resistance is low, the voltage signal will decrease and the PCM will interpret the low voltage as warm fuel.

Glow Plug--Range 0-25.5 Volts: The amount of voltage applied to the glow plug system. The scan tool can be used to indicate if the glow plugs actually turned ON by monitoring the voltage drop. Also, a good functional check of the glow plug relay.

Glow Plug System--Range Enabled/Disabled: Glow Plug System-Range ON/OFF Indicates whether or not the powertrain control module (PCM) has requested the glow plugs to be turned ON.

IAT--Range -40 to +151°C (-40 to +304°F): The intake air temperature (IAT) sensor sends a signal to the powertrain control module (PCM) relative to the incoming air. The IAT is used by the PCM to adjust the fuel delivery.

Ignition Volts--Range 0-25.5 Volts: This represents the system voltage measured by the powertrain control module (PCM) at its ignition feed circuit. Ignition voltage is only present when the vehicle is running.

Inj. Pump Cam Reference Missed--Range 0-8: The scan tool will display the number of cam pulses missed. At idle, the Inj. Pump Cam Reference Missed range should read 0.

Inj. Pump Sol. Closure Time--Range 0.0-4.0 milliseconds: Indicates the amount of time the fuel solenoid takes to close. When engine load is increased, the closure time will fluctuate.

Last Odometer--Range Miles:  The amount of miles since the last failure in 3 mile increments. Every time a failure occurs, the last odometer will reset to zero.

Lift Pump--Range 0-25.5 Volts: The amount of voltage the lift pump system is drawing. Also, a good functional check of the lift pump relay and the oil pressure switch.

Lift Pump System--Range Disabled/Enabled: Indicates whether or not the powertrain control module (PCM) has requested the lift pump to be turned ON. This display can not be used to determine if the lift pump is actually ON.

MIL--Range ON/OFF: Represents the commanded state of the Service Engine Soon malfunction indicator lamp (MIL).

No Results Counter: The number of ignition cycles without a pass or fail result.

Number of DTCs--Range #: Indicates the total number of current DTCs set, but does not necessarily mean that the MIL is illuminated.

Pass Counter--Range (Decimal): The number of ignition cycles that a test has run and passed at least once.

PCM in VTD Fail Enable: The scan tool will display Yes or No. This will indicate that the powertrain control module (PCM) has received the correct password from the Passlock® module and then a failure has occurred. The PCM will continue to enable fuel.

Resume Switch--Range ON/OFF: Indicates if the cruise control resume switch is activated. The scan tool may be used in order to determine if the cruise control resume set switch is functioning properly.

Service Throttle Soon Lamp--Range ON/OFF: Represents the commanded state of the Service Throttle Soon lamp.

Set Switch--Range ON/OFF: Indicates if the cruise control set switch is activated. The scan tool may be used to determine if the cruise control set switch is functioning properly.

Startup Coolant--Range -40 to +151°C (-40 to +304°F): A reading of the vehicles coolant temperature at start-up. This will change with every key cycle.

TDC OFFSET--Range -2.50 to +2.50 Degrees: The powertrain control module (PCM) has the ability to determine the amount of offset that is needed to bring the engine to top dead center (TDC). This is used by the PCM in order to determine the proper injection timing and the fuel delivery. This value may be displayed as a positive or negative number.

Trans. Fluid Temp.--Range -40 to +151°C (-40 to +304°F): This value represents the input signal of the transmission fluid temperature sensor.

Vehicle Speed--Range 0-98: Vehicle speed is a powertrain control module (PCM) internal parameter. The vehicle speed is computed by timing pulses coming from the vehicle speed sensor (VSS). Vehicle speed is used to check the torque converter clutch (TCC) lock-up speed or speedometer accuracy. The speed is displayed in both kilometers per hour (km/h) and miles per hour (mph).

VTD Auto Learn Timer: The scan tool will display active or inactive. The Auto Learn Timer will indicate if the vehicle theft deterrent (VTD) system is in the learn mode and has not timed out.

VTD Fuel Disable: The scan tool will display Active or Inactive. If the powertrain control module (PCM) has not received the correct password from the Passlock® module the PCM will disable fuel, and Active will be displayed on the scan tool.

VTD Fuel Disable Until Ign. Off: The scan tool will display Yes or No. With the ignition ON and a vehicle theft deterrent (VTD) code stored, the scan tool will display Yes.

Wastegate Solenoid--Range 0-100 Percent: The powertrain control module (PCM) cycles the boost solenoid pulse-width-modulated (PWM) ON and OFF. The ON time, or duty cycle, of the solenoid valve is expressed as a percent. The boost PWM solenoid meters the vacuum level at the wastegate valve actuator as commanded by the PCM.