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 Powertrain On-Board Diagnostic (OBD) System Check first. The OBD System Check will confirm proper system operation.

A/C Compressor--Range engaged/disengaged: Indicates whether or not the 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 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 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%: Computed by the PCM from APP module voltage (throttle position) and should display 0% at idle and 100% at wide open throttle.

APP 1--Range 0-5 Volts: The PCM uses the 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 about 0.35-0.95 volts at idle to above 4.0 volts at wide open throttle.

APP 2--Range 0-5 Volts: The PCM uses the 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 about 4.5 volts at idle and steadily decrease to about 1.0 volt at wide open throttle.

APP 3--Range 0-5 Volts: The PCM uses the 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 3 should read about 4.0 volts at idle and steadily decrease to about 2.5 volts at wide open throttle.

BARO--Range 10-105 kPa, 0-5 Volts: The 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, 0-5.0 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 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 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 it should read 0.

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

Cruise Brake Switch--Range open/closed: When the brake pedal is applied, the switch sends a signal to the PCM to disengage the cruise control.

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

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

Des. Inj. Timing--Range 0-25.5 Degrees: The amount of injection timing requested by the PCM.

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

ECT--Range -40°C to 151°C, -40°F to 304°F: The Engine Coolant Temperature (ECT) sensor sends a signal to the PCM relative to engine coolant temperature. 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.

ECT Sensor--Range 0-5 Volts: The Engine Coolant Temperature (ECT) sensor sends a signal to the PCM relative to engine coolant temperature. 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.

Engine Load--Range 0-100%: 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 Shutoff Sol.--Range ON/OFF: The ESO is located on the fuel injection pump. When the ignition switch is OFF, the ESO is in the NO FUEL position. It prevents fuel from entering the fuel injection pump.

Engine Speed--Range 0-9999 RPM: Engine speed is computed by the PCM from the crankshaft position sensor. If the crankshaft position sensor is inoperative, an rpm reading is taken from the injection pump cam signal. It should remain close to desired idle under various engine loads with engine idling. Engine speed value is very accurate.

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

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

Fuel Temperaure--Range -28°C to 140°C, -18°F to 285°F: There is a thermistor located in the optical sensor that determines fuel temperature. When the sensor is cold (internal resistance high) the PCM monitors a high signal voltage which it interprets as low fuel temperature. As the sensor warms (internal resistance 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 PCM has requested the glow plugs to be turned ON.

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

Ignition Volts--Range 0-25.5 volts: This represents the system voltage measured by the 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 it 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, closure time will fluctuate.

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 oil pressure switch.

Lift Pump System--Range disabled/enabled: Indicates whether or not the 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 (MIL) lamp.

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

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

Resume Switch--Range ON/OFF: Indicates if the cruise control resume switch is activated. The scan tool may be used 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°C to 151°C, -40°F to 304°F: A reading of the vehicles coolant temperature at startup. This will change every key cycle.

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

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

Vehicle Speed--Range 0-98: Vehicle speed is a PCM internal parameter. It is computed by timing pulses coming from the Vehicle Speed Sensor (VSS). Vehicle speed is used in checking TCC lock-up speed or speedometer accuracy. Speed is displayed in both Miles Per Hour (mph) and Kilometers Per Hour (km/h).

VTD Auto Learn Timer: The scan tool will display active or inactive. The Auto Learn Timer wil indicate if the 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 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 igntion On and a VTD code stored, the scan tool will display yes.

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

Freeze Frame and Failure Record Data Definitions: A freeze frame and failure record data list consists of as many of the same parameters as in an Engine data list. The list below defines the parameters not found in a Engine data list.

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 or failure record has been stored.

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

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

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