The following information will assist in diagnosing emission or driveability problems. The technician can view the displays while the vehicle is being driven. Refer to Powertrain On Board Diagnostic (OBD) System Check for additional information.

The data messages displayed on the scan tool are divided into Engine, Specific Engine, and DTC lists as follows:

Engine Data

Specific Engine Data

DTC Data

Engine 1 Data Definitions

Engine Speed - Range 0-16384 RPM: Engine Speed is computed by the PCM from the fuel control reference input.

Desired Idle Speed - 0-3187 RPM: The PCM commands the idle speed. The PCM compensates for various engine loads in order to maintain the desired idle speed. The actual RPM's should remain close to the desired idle under the various engine loads with the engine idling.

ECT - Range -40° C-215° C (-40° F-419° F): The Engine Coolant Temperature (ECT) sensor sends a signal to the PCM relative to the engine coolant temperature. The PCM then converts this signal to degrees Celsius. The PCM uses the engine coolant temperature in order to adjust the fuel delivery and the spark timing.

IAT - Range -40° C-215° C (-40° F-419° F): The Intake Air Temperature (IAT) sensor sends a signal to the PCM relative to the intake incoming air. The PCM converts the signal of the IAT sensor to degrees Celsius. The PCM uses the intake air temperature in order to adjust the fuel delivery and the spark timing.

MAP - Range 11-105 kPa, 0-5.0 Volts: The Manifold Absolute Pressure (MAP) sensor measures the intake manifold pressure. The manifold pressure changes with the engine speed changes and engine load changes. The PCM uses the manifold absolute pressure in order to adjust the fuel delivery and the spark timing.

BARO - Range 11-105 kPa, 0-5.0: The Barometric (BARO) pressure is read from the MAP sensor when the ignition is ON and the engine is off and at wide open throttle. The PCM uses the BARO in order to adjust the fuel delivery and the spark control due to the altitude changes.

TP Sensor - Range 0.0-0.5 Volts: The PCM uses the Throttle Position (TP) sensor to determine the amount of the throttle demanded by the operator of the vehicle. The TP sensor reads between 0.36-0.96 volt at idle to above 4.0 volts at Wide Open Throttle (WOT).

TP Angle - Range 0-100 %: The PCM computes the Throttle Position (TP) from the TP sensor voltage input. The TP angle will auto zero to 0 % at idle when the TP voltage is below 0.90 volt. The TP angle will read 100 % at Wide Open Throttle (WOT).

O2S 1 - Range 0-1132 mV: The reading represents the exhaust oxygen sensor output voltage. This voltage will fluctuate constantly between 100 mV (lean exhaust) to 900 mV (rich exhaust) when operating in a Closed Loop.

HO2S Sensor 2 - Range 0-1132 mV: The Rear Heated Oxygen Sensor (HO2S 2) represents the exhaust oxygen output voltage past the catalytic converter. This voltage remains inactive, or the voltage will appear lazy within a range of 100 mV (lean exhaust) and 900 mV (rich exhaust) when the system is operating in a Closed Loop.

Fuel Trim Cell - Range 0-22: A Fuel Trim Cell depends upon the engine speed and the MAP sensor readings. RPM vs. MAP is broken down into 22 fuel trim cells. The Fuel Trim Cell indicates which cell is currently active.

Fuel Trim Index - Range 0-255 (-100 % to 100 %): The Fuel Trim (FT) Index represents the average Long Term Fuel Trim for certain cells which are used in determining DTC P0171 and P0172.

Short Term FT - Range 0-255 (-100 % to 100 %): The Short Term Fuel Trim represents a short term correction of the fuel delivery. The correction is in response to the amount of time the oxygen sensor voltage is above or below 450 mV. An oxygen sensor voltage below 450 mV indicates a lean air to fuel mixture. If the oxygen sensor has mainly read below 450 mV, the short term fuel trim will increase in order to command the PCM to add fuel. If the oxygen sensor voltage stays mainly above the threshold, the PCM will reduce the fuel delivery in order to compensate for the indicated rich condition.

Long Term FT - Range 0-255 (-100 % to 100 %): The Long Term Fuel Trim (FT) is derived from the short term fuel trim value. The Long Term Fuel Trim (FT) is used for the long term correction of the fuel delivery. A value of the 128 counts (0 %) indicates that the fuel delivery requires no compensation in order to maintain a 14.7:1 air to fuel ratio. A value below 128 counts means that the fuel system is too rich and the fuel delivery is being reduced. The PCM is decreasing the injector pulse width. A value above 128 counts indicates that a lean condition exists for which the PCM is compensating.

Short Term FT Average - Range 0-255 (-100 % to 100 %): The Short Term Fuel Trim (FT) Average is derived from the short term fuel trim from all of the cells. The PCM takes all of the values. The PCM then creates one average value.

Long Term FT Average - Range 0-255 (-100 % to 100 %): The Long Term Fuel Trim (FT) Average is derived from the long term fuel trim from all of the cells. The PCM takes all of the values. The PCM then creates one average value.

Low Octane Spark Modifier - Range 0-90 degrees: The Low Octane Fuel Spark Modifier indicates the long term amount of the spark advance the PCM removes from the ignition control. The PCM responds to the Knock Sensor (KS) signal.

Spark - Range 64 to -64 degrees: Spark is the amount of spark the PCM programs in the ignition system. The PCM computes the desired spark advance. The PCM uses the engine coolant temperature, he engine RPM, the engine load, the vehicle speed, the operating mode.

Knock Retard - 0-90 degrees: The Knock Sensor (KS) retard is the amount spark advance the PCM removes from the IC.

KS Noise Channel - Range Yes/No: The KS Noise Channel indicates when the PCM detects the Knock Sensor (KS) signal. The PCM should display No at idle.

KS Active Counter - Range 0-255 Counts: The Knock Sensor (KS) activity counter indicates if the PCM is receiving the varying frequency output of the KS. The KS counter increases with the engine speed.

Med. Resolution Resync Counter - Range 0-255 Counts: The medium resolution resync counter displays the number of times the PCM had to resync the Crankshaft Position (CKP) sensor. The Med. Resolution Resync Counter is helpful in diagnosing the DTC P0335.

CKP Active Counter - Range 0-255 Counts: The Crankshaft Position (CKP) activity counter displays the number of 7x resync pulses from the ignition module.

CMP Active Counter - Range 0-255 Counts: The Camshaft Position (CMP) activity counter displays the activity sent to the PCM from the CMP sensor. The counter will continually increment while the engine is running. The CMP Act. Counter is helpful in diagnosing the DTC P0342.

Med. Resolution Engine Sync. - Range YES/NO: The medium resolution engine sync. displays if the PCM is receiving the 7x sync pulse. The Med. Resolution Engine Sync. is helpful in diagnosing the DTC P0300 and P0301-P0304.

CMP Resync Counter - Range 0-255 Counts: The Camshaft Position (CMP) resync counter displays the number of times the PCM had to resync with the CMP sensor. The CMP Resync Counter is helpful in diagnosing the DTC P0341.

Purge Lrn. Mem. - Range 0.00-1.00: The purge learn memory is a display of the PCM adding or subtracting the fuel. The purge learn memory is based on the EVAP Purge. This number is added to the fuel trim calculations. The fuel is added or subtracted there. A number near 1 indicates that the fuel is being added to the fuel trim. A number near 0 indicates that fuel is being taken away from the fuel trim.

EVAP Canister Purge- Range 0-100 %: The Evaporative Emission (EVAP) purge valve solenoid is a proportional signal used in order to control the evaporative emission canister purge function. At 0 % the valve is commanded fully closed. 100 % implies that the valve is fully open.

IAC Position - Range 0-255 Counts: The Idle Air Control (IAC) pintle position command from the PCM is displayed in counts. The higher the counts read, the greater the commanded idle speed is. The idle air control responds fairly quickly to changes in the engine load in order to maintain the desired idle RPM.

Transmission Range - Range Valid/Invalid: Trans Range represents the decoded status of the four inputs from the Transaxle Range Switch Assembly. The combination of Transaxle range inputs the position of the Transaxle manual valve.

Vehicle Speed km/h - 0-255 MPH, 0-255 km/h : The PCM converts the vehicle speed sensor into MPH (km/h) for the display. From the PCM, the vehicle speed output is 4000 pulses per mile. The scan tool uses the class 2 serial data from the PCM in order to obtain the vehicle speed. The instrument panel cluster, the cruise control module, and the multi-function alarm module use the 4000 ppm output.

Ignition 1 - Range 0-25.5 volts: The ignition volts represents the system voltage measured by the PCM at the ignition feed circuit.

Loop Status - Range Open/Closed: A Closed Loop displayed indicates that the PCM is controlling the fuel delivery according to the Oxygen Sensor voltage. The PCM controls the fuel delivery air to fuel ratio as close to 14.7:1 as possible.

Power Enrichment - Active/Inactive: Active displayed indicates that the PCM has detected conditions appropriate to operate in power enrichment mode. The PCM will command Power Enrichment mode when a large increase in throttle position and load is detected. While in Power Enrichment, the PCM will increase the amount of fuel delivered by entering Open Loop and increasing the injector pulse width. This is done to prevent a possible sag or hesitation from occuring during acceleration.

Calc. Air Flow- Range 0-512 g/s:: The calculated air flow is a calculation based on the manifold absolute pressure. Several diagnostics use the Air Flow Calculation in order to determine when to run.

Engine Load - Range 0-100%:: The load indicates the engine load based on the manifold absolute pressure. The higher the percentage, the greater the load the engine is under.

Engine Run Time - Range 0:00:00-18:12:15 hours:minutes:seconds: The engine run time is a measure of how long the engine has been running. When the engine stops running, the timer resets to zero.

# of Curr. DTCs - Range 0-255: The # of Curr. DTCs 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.

Engine 2 Data Definitions

Engine Speed - Range 0-16384 RPM: From the fuel control reference input, the PCM computes the Engine Speed. The engine speed should remain close to the desired idle under the various engine loads with the engine idling.

Desired Idle Speed- Range 0-3187 RPM: The PCM commands the idle speed. The PCM compensates for the various engine loads in order to keep the engine at the desired idle speed.

ECT - Range -40° C to 215° C (-40° F to 419° F): The Engine Coolant Temperature (ECT) sensor sends the engine temperature information to the PCM. The PCM supplies 5 volts to the engine coolant temperature sensor circuit. The sensor is a thermistor which changes the internal resistance as the temperature changes. When the sensor is cold meaning the internal resistance is high, the PCM monitors a high voltage which the PCM interprets as a cold engine. As the sensor warms meaning the internal resistance decreases, the voltage signal decreases. The PCM interprets the lower voltage as a warm engine.

IAT - Range -40° C to 215° C(-40° F to 419° F): The PCM converts the resistance of the Intake Air Temperature (IAT) sensor to degrees in the same manner as the ECT sensor. The PCM uses the intake air temperature in order to adjust the fuel delivery and the spark timing according to the incoming air density.

MAP - Range 11-105 kPa, 0-5.0 Volts: The Manifold Absolute Pressure (MAP) sensor measures the change in the intake manifold pressure which results from the engine load changes and the engine speed changes. As the intake manifold pressure increases, the air density in the intake also increases.

BARO - Range 11-105 kPa: The Barometric Pressure (BARO) sensor measures the change in the intake manifold pressure which results from the altitude changes. This value is updated when the ignition is turned ON and at a Wide Open Throttle (WOT).

TP Sensor - Range 0-5.0 Volts: The PCM uses the Throttle Position (TP) sensor in order to determine the amount of the throttle demanded by the vehicle's operator. The TP sensor reads between 0.36-0.96 volt at idle to above 4 volts at Wide Open Throttle (WOT).

TP Angle - Range 0-100 %: From the TP sensor voltage input, the PCM computes the Throttle Position. The TP angle will auto zero to 0 % at idle (TP voltage below 0.90 volt). The TP angle will read 100 % at Wide Open Throttle.

Total Misfire Current Counter - Range 0-255 Counts: Indicates the total number of misfires that have been detected in all the cylinders after the 100 engine cycles. One cycle equals one complete 4 stroke cycle. The total misfire only increments during the steady state cruise conditions.

Air Fuel Ratio - Range 0:1-25.5:1: The Air Fuel Ratio indicates the air to fuel ratio based on the Oxygen Sensor (O2S 1) inputs. The PCM uses the fuel trims to adjust fueling in order to attempt to maintain an air fuel ratio of 14.7:1.

Base PWM Cyl. 1 - Range 0-999.9 mS: The base PWM Cyl. 1 indicates the base Pulse Width Modulation (PWM) or the ON time of the cylinder 1 injector in milliseconds. When the engine load increases, the injector pulse width increases.

Base PWM Cyl. 2 - Range 0-999.9 mS: The base PWM Cyl. 2 indicates the base Pulse Width Modulation (PWM) or the ON time of the cylinder 2 injector in milliseconds. When the engine load increases, the injector pulse width increases.

Base PWM Cyl. 3 - Range 0-999.9 mS: The base PWM Cyl. 3 indicates the base Pulse Width Modulation (PWM) or the ON time of the cylinder 3 injector in milliseconds. When the engine load increases, the injector pulse width increases.

Base PWM Cyl. 4 - Range 0-999.9 mS: The base PWM Cyl. 4 indicates the base Pulse Width Modulation (PWM) or the ON time of the cylinder 4 injector in milliseconds. When the engine load increases, the injector pulse width increases.

A/C Request - Range Yes/No: The A/C Request Represents whether the HVAC selector is requesting the Air Conditioning (A/C) system. The PCM receives the input. Finally the scan tool receives the input over the class 2 serial data.

A/C High Side Pressure - Range 0.0-5.0 Volts, 0.0-3165 kPa: The A/C High Side displays the pressure value of the A/C refrigerant pressure sensor. The A/C High Side helps diagnose the DTC P0530.

A/C Relay - Range Off/On: The A/C Relay represents the commanded state of the A/C clutch control relay. The A/C clutch should be engaged when the scan tool displays ON.

Stepper Cruise Motor- Range Disable/Enabled: The Stepper Cruise display indicates if the PCM is allowing the cruise operation. The PCM has the ability to disable the cruise control under certain conditions.

Cruise - Range Yes/No: The cruise engaged is an input from the cruise control module to the PCM. The cruise engaged indicates if the cruise control is in control of the vehicle. The PCM uses this information to change the transmission shift calibrations and to turn ON an indicator lamp on the Instrument Panel Cluster (IPC). The cruise engaged helps diagnose the Cruise Control Diagnosis.

TR Switch - P, A, B, C - Scan Tool Displays High or Low: The TR switch P, A, B, C display represents the states of the four inputs from the Transaxle Range Pressure Switch Assembly. "High" indicates a B+ voltage signal being monitored at the PCM, "Low" indicates a grounded input signal. The combinationof Transaxle range inputs indicates the position of the Transaxle manual valve.

Transmission Range - Range Valid/Invalid: Trans Range represents the decoded status of the four inputs from the Transaxle Range Switch Assembly. The combination of Transaxle range inputs the position of the Transaxle manual valve.

Vehicle Speed km/h - 0-255 MPH, 0-255 km/h : The PCM converts the vehicle speed sensor into MPH (km/h) for the display. From the PCM, the vehicle speed output is 4000 pulses per mile. The scan tool uses the class 2 serial data from the PCM in order to obtain the vehicle speed. The instrument panel cluster, the cruise control module, and the multi-function alarm module use the 4000 ppm output.

Output Driver 1 - Range SHRT00000000 Open00000000 (binary display): The PCM uses the Ouput Driver Modules in order to allow the various systems to function by providing a ground circuit. The scan tool displays 0s in each of the 8 positions when the circuitry is OK. If a 1 appears in any of the positions, then PCM detects either a short circuit or an open circuit. Refer to Powertrain Control Module Outputs Diagnosis .

Output Driver 2 - Range SHRT00000000 Open00000000 (binary display): The PCM uses the Ouput Driver Modules in order to allow the various systems to function by providing a ground circuit. The scan tool displays 0s in each of the 8 positions when the circuitry is OK. If a 1 appears in any of the positions, then PCM detects either a short circuit or an open circuit. Refer to Powertrain Control Module Outputs Diagnosis .

Engine Run Time - Range 0:00:00-18:12:15 hours:minutes:seconds: The engine run time is a measure of how long the engine has been running. When the engine stops running, the timer resets to zero.

# of Curr. DTCs - Range 0-255: The # of Curr. DTCs 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.

Specific Eng. Misfire Data Definitions

Engine Speed - Range 0-16384: From the fuel control reference input, the PCM computes the Engine Speed. The engine speed should remain close to the desired idle under the various engine loads with the engine idling.

Desired Idle Speed- Range 0-3187 RPM: The PCM commands the idle speed. The PCM compensates for the various engine loads in order to keep the engine at the desired idle speed.

ECT - Range -40° C to 215° C (-40° F to 419° F): The Engine Coolant Temperature (ECT) sensor sends the engine temperature information to the PCM. The PCM supplies 5 volts to the engine coolant temperature sensor circuit. The sensor is a thermistor. The thermistor the internal resistance as the temperature changes. When the sensor is cold indicating the internal resistance is high, the PCM monitors a high voltage. The PCM interprets as a cold engine. As the sensor warms indicating that the internal resistance is decreasing, the voltage signal decreases. The PCM interprets the lower voltage as a warm engine.

IAT - Range -40° C to 215° C (-40° F to 419° F): The PCM converts the resistance of the Intake Air Temperature (IAT) sensor to degrees in the same mode as the ECT sensor. The PCM uses the intake air temperature in order to adjust the fuel delivery and the spark timing according to the incoming air density.

MAP - Range 11-105 kPa, 0.0-5.0 Volts: The Manifold Absolute Pressure (MAP) sensor measures the change in the intake manifold pressure. The change in the intake manifold pressure results from engine load changes and speed changes. As the intake manifold pressure increases, the air density in the intake also increases. Additional fuel is required.

BARO - Range 11-105 kPa: The Barometric Pressure (BARO) sensor measures the change in the intake manifold pressure which results from the altitude changes. The BARO updates when the ignition is turned ON and at Wide Open Throttle (WOT).

TP Sensor - Range 0.0-5.0 Volts: The PCM uses the Throttle Position (TP) sensor in order to determine the amount of the throttle demanded by the vehicle's operator. The TP sensor reads between 0.36-0.96 volt at idle to above 4 volts at Wide Open Throttle (WOT).

TP Angle - Range 0-100 %: The PCM computes the Throttle Position (TP) angle from the TP sensor voltage input. The TP angle will auto zero to 0 % at idle. The TP voltage will read below 0.90 volt. The TP angle will read 100 % at Wide Open Throttle (WOT).

Misfire Current Cyl. 1 Range 0-255 Counts: The misfire cur. #1 indicates the number of current misfires that are present in cylinder #1. The misfire cur. 1 increments only when the misfire is current.

Misfire History Cyl. 1 - Range 0-255 Counts: The Misfire Hist. #1 indicates the number of misfires that have occurred after the PCM has counted 195 current misfires. After 195 total misfires, the current misfire counter adds the misfires to the history misfire counter. If 1 cylinder is misfiring, the misfire current counter will count 195 misfires before adding the misfires to the history counter. If 2 cylinders are misfiring, the misfiring current counters add to the history counters after 97 misfires.

Calc. Air Flow - Range 0-512 g/s: The calculated air flow is a calculation based on the manifold absolute pressure. The calculation is used in several diagnostics in order to determine when to run.

Engine Load- Range 0-100 %: The LOAD indicates the engine load based on the manifold absolute pressure. The higher the percentage, the more load the engine is under.

Base PWM Cyl. 1 - Range 0-999.9 mS: The base PWM Cyl. 1 indicates the base Pulse Width Modulation (PWM) or the ON time of the cylinder 1 injector in milliseconds. When the engine load increases, the injector pulse width increases.

Total Misfire Current Count - Range 0-255 Counts: The Total Misfire indicates the total number of misfires that have been detected in all cylinders after 100 engine cycles. One cycle equals the completion of a 4 stroke cycle. The total misfire only increments during a steady state cruise conditions.

Engine Run Time - Range 0:00:00-18:12:15 hours:minutes:seconds: The engine run time is a measure of how long the engine has been running. When the engine stops running, the engine resets to 0.

Number of Current DTCs - Range 0-255: The # of Curr. DTCs 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.

Specific Eng. O2S Data Definitions

O2S 1 - Range 0-1132 mV: The Oxygen Sensor (O2S 1) represents the exhaust oxygen sensor output voltage. This voltage fluctuates constantly within a range of 100 mV (lean exhaust) to 900 mV (rich exhaust) when operating in a Closed Loop.

HO2S Sensor 2 - Range 0-1132 mV: The Rear Heated Oxygen Senor (HO2S 2) represents the exhaust oxygen output voltage after the catalytic converter. When this system is operating in a Closed Loop, this voltage remains inactive, or this voltage appears lazy within a range of 100 mV and 900 mV. A lean exhaust reads at 100 mV. A rich exhaust reads at 900 mV.

Engine Speed - Range 0-16384 RPM: The PCM computes the engine speed from the fuel control reference input. The engine speed should remain close to the desired idle under various engine loads with the engine idling.

Desired Idle Speed - Range 0-3187 RPM: The PCM commands the idle speed. The PCM compensates for various engine loads in order to keep the engine at the desired idle speed.

ECT - Range -40° C to 215° C (-40° F to 419° F): The Engine Coolant Temperature (ECT) sensor sends the engine temperature information to the PCM. The PCM supplies 5 volts to the engine coolant temperature sensor circuit. The sensor is a thermistor which changes the internal resistance as the temperature changes. When the sensor is cold, the internal resistance is high. The PCM monitors a high voltage which the PCM interprets as a cold engine. As the sensor warms, the internal resistance decreases, and the voltage signal decreases. The PCM interprets the lower voltage as a warm engine.

IAT - Range -40° C to 215° C (-40° F to 419° F): The PCM converts the resistance of the Intake Air Temperature (IAT) sensor to degrees in the same mode as the ECT sensor. The PCM uses the intake air temperature in order to adjust the fuel delivery and the spark timing according to the incoming air density.

MAP - Range 11-105 kPa, 0.0-5.0 Volts: The Manifold Absolute Pressure (MAP) sensor measures the change in the intake manifold pressure. These changes result from engine load changes and speed changes. As the intake manifold pressure increases, the air density in the intake increases. Additional fuel is then required.

BARO - Range 11-105 kPa: The Barometric Pressure (BARO) sensor measures the change in the intake manifold pressure. This change results from altitude changes. The value is updated when the ignition is turned ON and at Wide Open Throttle (WOT).

TP Sensor - Range 0.0-5.0 Volts: The PCM uses the Throttle Position (TP) sensor in order to determine the amount of throttle demanded by the vehicle's operator. The TP sensor reads between 0.36-0.96 volt at idle to above 4 volts at WOT.

TP Angle - Range 0-100 %: The PCM computes the Throttle Position (TP) angle from the TP sensor voltage input. The TP angle will auto zero to 0 % at idle. The TP voltage will read below 0.90 volt. The TP angle will read 100 % at Wide Open Throttle (WOT).

Short Term FT - Range 0-255 (-100 % to 100 %): The Short Term Fuel Trim represents a short term correction of the fuel delivery. The correction is in response to the amount of time the oxygen sensor voltage is above or below 450 mV. An oxygen sensor voltage below 450 mV indicates a lean air to fuel mixture. If the oxygen sensor has mainly read below 450 mV, the short term fuel trim will increase in order to tell the PCM to add fuel. If the oxygen sensor voltage stays mainly above the threshold, the PCM will reduce the fuel delivery in order to compensate for the indicated rich condition.

Long Term - Range 0-255 (-100 % to 100 %): The Long Term Fuel Trim (FT) is derived from the short term fuel trim value. The Long Term Fuel Trim (FT) is used for the long term correction of the fuel delivery. A value of the 128 counts (0 %) indicates that the fuel delivery requires no compensation in order to maintain a 14.7:1 air to fuel ratio. A value below 128 counts means that the fuel system is too rich and the fuel delivery is being reduced. A value above 128 counts indicates that a lean condition exists for which the PCM is compensating.

Short Term FT Average - Range 0-255 (-100 % to 100 %): The Short Term Fuel Trim (FT) Average is derived from the short term fuel trim from all of the cells. The PCM takes all of the values. The PCM then creates one average value.

Long Term FT Average - Range 0-255 (-100 % to 100 %): The Long Term Fuel Trim (FT) Average is derived from the long term fuel trim from all of the cells. The PCM takes all of the values. The PCM then creates one average value.

Lean/Rich Transition - Range 0-255 Counts: The PCM counts the number of times the Oxygen Sensor (O2S1 goes from a low voltage to a high voltage within a 100 seconds. A low voltage reading indicates a lean exhaust. A high voltage reading indicates a rich exhaust.

Rich/Lean Transition - Range 0-255 Counts: The PCM counts the number of times the Oxygen Sensor (O2S1 goes from a high voltage to a low voltage within a 100 seconds. A low voltage reading indicates a lean exhaust. A high voltage reading indicates a rich exhaust.

Lean/Rich Avg. - Range 0-249 mS Counts: Following the completion of the data collection period, the PCM takes the Lean/Rich transition times. The PCM averages the transition time from the total transition times.

Rich/Lean Avg. - Range 0-249 mS: Following the completion of the data collection period, the PCM takes the Rich/Lean transition times. The PCM divides the value with the 100 second period.

Rich/Lean to Lean/Rich Ratio Bn 1 Sen. 1 - Range 0:1-15.93:1: The Rich/Lean Average is divided by the Lean/Rich average in order to find the Oxygen Sensor (O2S 1) ratio.

Calc. Air Flow - Range 0-512 g/s: The calculated air flow is a calculation based on the manifold absolute pressure. Several diagnostics use the Air Flow Calculation in order to determine when to run.

Engine Load - Range 0-100%: The LOAD indicates the engine load based on the manifold absolute pressure. The higher the percentage, the greater the load the engine is under.

Loop Status - Range Open/Closed: A Closed Loop displayed indicates that the PCM is controlling the fuel delivery according to the Oxygen Sensor voltage. The PCM controls the air to fuel ratio as close to 14.7:1 as possible.

Number of Current DTCs - Range 0-255: The # of Curr. DTCs 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.

Engine Run Time - Range 0:00:00-18:12:15 hours:minutes:seconds: The engine run time is a measure of how long the engine has been running. When the engine stops running, the timer resets to zero.

DTC Freeze Frame Data Definitions

DTC Freeze Frame - Range 0-100 %: The DTC Freeze Frame Indicates which DTC this freeze frame information is. Clearing the DTCs erases the freeze frame information. Record the information before clearing any DTCs.

Air Fuel Ratio - Range 0:1-25.5:1: The Air Fuel Ratio indicates the air to fuel ratio based on the Oxygen Sensor (O2S 1) inputs. The PCM uses the fuel trims to adjust fueling in order to attempt to maintain an air fuel ratio of 14.7:1.

Calc. Air Flow - Range 0-512 g/s: The calculated air flow is a calculation based on the manifold absolute pressure. Several diagnostics use the Air Flow Calculation in order to determine when to run.

ECT - Range -40° C-215° C (-40° F-419° F): The Engine Coolant Temperature (ECT) sensor sends the engine temperature information to the PCM. The PCM supplies 5 volts to the engine coolant temperature sensor circuit. The sensor is a thermistor. The thermistor changes the internal resistance as the temperature changes. When the sensor is cold indicating the internal resistance is high, the PCM monitors a high voltage. The PCM interprets as a cold engine. As the sensor warms indicating that the internal resistance is decreasing, the voltage signal decreases. The PCM interprets the lower voltage as a warm engine.

BARO - Range 11-105 kPa: The Barometric Pressure (BARO) sensor measures the change in the intake manifold pressure. This change results from altitude changes. The value is updated when the ignition is turned ON and at Wide Open Throttle (WOT).

Base PWM Cyl. 1 - Range 0-999.9 mS: The base PWM Cyl. 1 indicates the base Pulse Width Modulation (PWM) or the ON time of the cylinder 1 injector in milliseconds. When the engine load increases, the injector pulse width increases.

Short Term FT - Range (-100 % to 100 %): The Short Term Fuel Trim represents a short term correction of the fuel delivery. The correction is in response to the amount of time the oxygen sensor voltage is above or below 450 mV. An oxygen sensor voltage below 450 mV indicates a lean air to fuel mixture. If the oxygen sensor has mainly read below 450 mV, the short term fuel trim will increase in order to tell the PCM to add fuel. If the oxygen sensor voltage stays mainly above the threshold, the PCM will reduce the fuel delivery in order to compensate for the indicated rich condition.

Long Term FT - Range (-100 % to 100 %): The Long Term Fuel Trim (FT) is derived from the short term fuel trim value. The Long Term Fuel Trim (FT) is used for the long term correction of the fuel delivery. A value of the 128 counts (0 %) indicates that the fuel delivery requires no compensation in order to maintain a 14.7:1 air to fuel ratio. A value below 128 counts means that the fuel system is too rich and the fuel delivery is being reduced. A value above 128 counts indicates that a lean condition exists for which the PCM is compensating.

MAP - Range 11-105 kPa, 0-5.0 Volts: The Manifold Absolute Pressure (MAP) sensor measures the intake manifold pressure. The manifold pressure changes with the engine speed changes and engine load changes. The PCM uses the manifold absolute pressure in order to adjust the fuel delivery and the spark timing.

Engine Speed - Range 0-16384 RPM: The PCM computes the engine speed from the fuel control reference input. The engine speed should remain close to the desired idle under various engine loads with the engine idling.

Loop Status - Range Open/Closed: A Closed Loop displayed indicates that the PCM is controlling the fuel delivery according to the Oxygen Sensor voltage. The PCM controls the air to fuel ratio as close to 14.7:1 as possible.

Vehicle Speed km/h - 0-255 MPH, 0-255 km/h : The PCM converts the vehicle speed sensor into MPH (km/h) for the display. From the PCM, the vehicle speed output is 4000 pulses per mile. The scan tool uses the scan tool uses the class 2 serial data from the PCM in order to obtain the vehicle speed. The instrument panel cluster, the cruise control module, and the multi-function alarm module use the 4000 ppm output.

LOAD - Range 0-100%: The LOAD indicates the engine load based on the manifold absolute pressure. The higher the percentage, the greater the load the engine is under.

TP Angle - Range 0-100 %: The PCM computes the Throttle Position (TP) angle from the TP sensor voltage input. The TP angle will auto zero to 0 % at idle. The TP voltage will read below 0.90 volt. The TP angle will read 100 % at Wide Open Throttle (WOT).

EGR/EVAP Data Definitions

Engine Speed - Range 0-16384: From the fuel control reference input, the PCM computes the Engine Speed. The engine speed should remain close to the desired idle under the various engine loads with the engine idling.

Desired Idle Speed - Range 0-3187 RPM: The PCM commands the idle speed. The PCM compensates for the various engine loads in order to keep the engine at the desired idle speed.

ECT - Range -40° C to 215° C (-40° F to 419° F): The Engine Coolant Temperature (ECT) sensor sends the engine temperature information to the PCM. The PCM supplies 5 volts to the engine coolant temperature sensor circuit. The sensor is a thermistor. The thermistor changes the internal resistance as the temperature changes. When the sensor is cold indicating the internal resistance is high, the PCM monitors a high voltage. The PCM interprets as a cold engine. As the sensor warms indicating that the internal resistance is decreasing, the voltage signal decreases. The PCM interprets the lower voltage as a warm engine.

IAT - Range -40° C to 215° C (-40° F to 419° F): The PCM converts the resistance of the Intake Air Temperature (IAT) sensor to degrees in the same mode as the ECT sensor. The PCM muses the intake air temperature in order to adjust the fuel delivery and the spark timing according to the incoming air density.

MAP - Range 11-105 kPa, 0.0-5.0 Volts: The Manifold Absolute Pressure (MAP) sensor measures the change in the intake manifold pressure. The change in the intake manifold pressure results from engine load changes and speed changes. As the intake manifold pressure increases, the air density in the intake also increases. Additional fuel is required.

BARO - Range 11-105 kPa: The Barometric Pressure (BARO) sensor measures the change in the intake manifold pressure which results from the altitude changes. This value updates when the ignition is turned ON and at Wide Open Throttle (WOT).

TP Sensor - Range 0.0-5.0 Volts: The PCM uses the Throttle Position (TP) sensor in order to determine the amount of the throttle demanded by the vehicle's operator. The TP sensor reads between 0.36-0.96 volt at idle to above 4 volts at Wide Open Throttle (WOT).

TP Angle - Range 0-100 %: The PCM computes the Throttle Position (TP) angle from the TP sensor voltage input. The TP angle will auto zero to 0 % at idle. The TP voltage will read below 0.90 volt. The TP angle will read 100 % at Wide Open Throttle (WOT).

O2S 1 - Range 0-1132 mV: The Oxygen Sensor (O2S 1) represents the exhaust oxygen sensor output voltage. This voltage fluctuates constantly within a range of 100 mV (lean exhaust) to 900 mV (rich exhaust) when operating in a Closed Loop.

HO2S Sensor 2 - Range 0-1132 mV: The Rear Heated Oxygen Senor (HO2S 2) represents the exhaust oxygen output voltage past the catalytic converter. When the system is operating in a Closed Loop, the voltage remains inactive. This voltage will appear lazy within a range of 100 mV to 900 mV. A lean exhaust reads close to 100 mV. A rich exhaust reads at 900 mV.

IAC Position - Range 0-255 Counts: The scan tool displays the PCM command for the Idle Air Control (IAC) pintle position in counts. The higher the number of counts, the greater the commanded idle speed reads. The Idle Air Control responds to changes in the engine load in order to maintain the desired idle RPM.

Fuel Trim Cell - Range 0-22: A Fuel Trim Cell depends upon the engine speed and the MAP sensor readings. RPM vs. MAP is broken down into 22 fuel trim cells. The Fuel Trim Cell indicates which cell is currently active.

Short Term FT - Range (-100 % to 100 %): The Short Term Fuel Trim represents a short term correction of the fuel delivery. The correction is in response to the amount of time the oxygen sensor voltage is above or below 450 mV. An oxygen sensor voltage below 450 mV indicates a lean air to fuel mixture. If the oxygen sensor has mainly read below 450 mV, the short term fuel trim will increase in order to tell the PCM to add fuel. If the oxygen sensor voltage stays mainly above the threshold, the PCM will reduce the fuel delivery in order to compensate for the indicated rich condition.

Long Term FT - Range (-100 % to 100 %): The Long Term Fuel Trim (FT) is derived from the short term fuel trim value. The Long Term Fuel Trim (FT) is used for the long term correction of the fuel delivery. A value of the 128 counts (0 %) indicates that the fuel delivery requires no compensation in order to maintain a 14.7:1 air to fuel ratio. A value below 128 counts means that the fuel system is too rich and the fuel delivery is being reduced. The PCM is decreasing the injector pulse width. A value above 128 counts indicates that a lean condition exists for which the PCM is compensating.

Decel EWMA - Range -10 to 10 kPa: The Exponentially Weighted Moving Average (EWMA) is an average kPa difference between the expected and the actual MAP kPA change. The EGR EWMA value should always measure near -3. Whenever the EGR EWMA becomes more positive, the EGR system is possibly restricted.

Desired EGR Position - Range 0 to 100 %: The desired EGR position is the commanded EGR position. The PCM calculates the desired EGR position. The higher the percentage, the longer the PCM is commanding the EGR valve ON.

Actual EGR Position - Range 0 to 100 %: The PCM monitors the results of its commands through a feedback signal. The EGR valve sends a voltage signal back to the PCM. The signal represents the actual EGR pintle position. The EGR pintle position should remain close to the desired EGR position.

EGR Flow Test Count - Range 0 to 255 Counts: The EGR Decel Trip Sample Counter is the total number of decel test samples this ignition cycle. The EGR Decel Trip Sample Counter should never indicate greater than 1 unless the technician has cleared an EGR DTC or the technician has disconnected the battery.

Loop Status - Range Open/Closed: A Closed Loop displayed indicates that the PCM is controlling the fuel delivery according to the Oxygen Sensor voltage. The PCM controls the fuel delivery air to fuel ratio as close to 14.7:1 as possible.

Purge Lrn. Mem. - Range 0.00-1.00: The purge learn memory is a display of the PCM adding or subtracting the fuel. The purge learn memory is based on the EVAP Purge. This number is added to the fuel trim calculations. The fuel is added or subtracted there. A number near 1 indicates that the fuel delivery is being added. A number near 0 indicates that fuel delivery is being reduced.

EVAP Canister Purge - Range 0 %-100 %: When energized, the EVAP Solenoid allows the fuel vapor to flow from the EVAP canister to the engine. The EVAP Solenoid is normally closed. The EVAP solenoid is pulse width modulated by the PCM. The EVAP Solenoid reads 0 % when closed to 100 % when fully opened.

EVAP Vent Sol. - Range Open/Closed: The EVAP Vent Solenoid allows fresh outside air to the EVAP canister during purge mode. The EVAP vent Solenoid allows the diagnostic to pull a vacuum on the fuel tank by closing the vent solenoid.

Fuel Level Range - 0 %--100 %: The Fuel Level Sensor monitors the fuel level in the tank. The fuel level sensor monitors the rate of change of the air pressure in the EVAP System. Several of the Enhanced EVAP System diagnostics are dependent upon the correct fuel level.

Fuel Tank Pressure - Range 0.0-5.0 Volts: The fuel tank pressure sensor measures the difference between the pressure or the vacuum in the fuel tank and the outside air pressure. When the air pressure in the fuel tank equals the outside air pressure, the output voltage of the sensor is 1.3 to 1.7 volts.

Engine Run Time - Range 0:00:00-18:12:15 hours:minutes:seconds: The engine run time is a measure of how long the engine has been running. When the engine stops running, the timer resets to zero.

Number of Current DTCs - Range 0-255: The # of Curr. DTCs 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.