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 Diagnostic System Check-Engine Controls first. The Diagnostic System Check will confirm proper system operation.

A/C Relay Command-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 F Signal-Range ON/OFF: Represents the state of the A/C request input from the control head.

APP Indicated Angle-Range 0-100 Percent: Computed by the PCM from APP module voltage, throttle position (TP), 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 about 0.35-0.95 volts at idle to above 4.0 volts at wide open throttle (WOT).

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 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 Sensor-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.

Boost Solenoid-Range 0-100 Percent: 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.

CKP Sensor Missed-Range 0-8: The scan tool will display the number of crank pulses missed. At idle the scan tool should read 0.

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

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

Cruise Resume Accel 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.

Cruise Set Coast 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.

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

Desired Idle-Range 0-3,187 RPM: The idle speed that is requested by the 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 PCM.

Device Control-Range YES/NO: Indicates if the scan tool has taken control of a system under output tests.

DTC Set This Ign.-Range #: Indicates the total number of current diagnostic trouble codes (DTCs) set this ignition cycle.

ECT Sensor-Range -40 to +151°C (-40 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 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 Shutoff Solenoid-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. The ESO prevents fuel from entering the fuel injection pump.

Engine Speed-Range 0-9,999 RPM: Engine speed is computed by the PCM from the crankshaft position sensor (CKP). If the crankshaft position sensor is inoperative, an RPM reading is taken from the injection pump cam signal. The engine speed should remain close to desired idle under various engine loads with the engine idling. Engine speed value is very accurate.

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

Fuel Pump Relay Feedback-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.

Fuel Pump Relay Command-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.

Fuel Temp.-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 (internal resistance high) the PCM monitors a high signal voltage which the PCM 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 Feedback Signal-Range 0-25.5 Volts: The amount of voltage the glow plug system is drawing. 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 Relay Command-Range ON/OFF: Glow Plug System-Range ON/OFF Indicates whether or not the PCM has requested the glow plugs to be turned ON.

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

Ignition 1 Signal-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 Sole. 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.

Injection Pump Timing Signal-Range 0-25.0 Degrees: Current actual injection timing.

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

# of Curr. 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 display is Yes or No. This will indicate that the PCM received a good password from the Passlock module and the vehicle has started and a failure has occurred. The PCM will continue to enable fuel.

PC Solenoid-On/Off: This value is the commanded state of the pressure control solenoid. Refer to Scan Tool Data Definitions in Automatic Transmission-4L80-E.

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

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

Stop Lamp Pedal Switch-Range Open/Closed: When the brake pedal is applied, the switch sends a signal to the PCM to disengage the cruise control.

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

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.

TFT-Range- -40 to +151°C (-40 to +304°F): This value represents the input signal of the transmission fluid temperature (TFT) sensor. Refer to Scan Tool Data Definitions in Automatic Transmission-4L80-E.

TR Switch-Range Park/Neutral, Reverse, Drive 4, Drive 3, Drive 2, Low and Invalid: These values represent the decoded sequence of the transmission range pressure switch assembly circuits and are to determine manual valve position.

VTD Auto Learn Timer: The scan tool display is Active or Inactive. The auto learn timer will indicate if the vehicle theft deterrent (VTD) system is in learn mode and has not timed out (10 minutes.)

VTD Fuel Disable: The scan tool display is Active or Inactive. If the PCM has not received the correct password from the Passlock module the PCM will disable fuel to the fuel system, and Active will be displayed on the scan tool.

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

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

Freeze Frame and Failure Record Data Definitions: A Freeze Frame/Failure Record data list consist of as many of the same parameters as in an engine data list. The list below defines the parameters not found in an engine data list.

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

First Odometer-Range Miles (x16): The amount of miles (in 16 mile increments) that the vehicle has traveled since the Freeze Frame/Failure Record has been stored.

Last Odometer-Range Miles (x16): Every time a failure occurs, last odometer will reset to zero. The amount miles since the last failure (in 16 mile increments).

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 ran and passed (at least once).