Engine Scan Tool Data Definitions. Chevrolet Corsica 1996

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1996 🢒 Corsica 🢒 Engine 🢒 Engine Controls - 2.2L 🢒 Engine Scan Tool Data Definitions

PCM Data Description

The following information will assist in diagnosing emission or driveability problems. The technician can view the displays while driving the vehicle. Refer to Powertrain OBD System Check for additional information.

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

Engine Data

•	Engine 1 -- Contains general information regarding the fuel delivery, the Ignition Control (IC), the Knock Sensor (KS), the Evaporative Emission (EVAP) and the basic engine operating conditions.

•	Engine 2 -- Contains general information regarding the fuel delivery Output Controls, the Ignition Control (IC), the Air Conditioning (A/C), the cruise control, and the basic engine operating conditions.

Specific Engine Data

•	EGR EVAP -- Contains the information that is specific to the Exhaust Gas Recirculation System (EGR), the Evaporative Emissions (EVAP) System diagnosis and the data that is required in order to verify the proper operation of the system.

•	Misfire -- Contains the information that is specific to the diagnosis of the misfire and the data that is required in order to verify the proper operation with regard to the misfire.

•	O2S -- Contains the information that is specific to the Oxygen Sensor (O2S 1) and the Rear Heated Oxygen Sensor (HO2S 2) diagnosis and the data that is required in order to verify the proper operation of the sensors.

DTC Data

•	Freeze Frame -- Contains the information that was collected during the time that a MIL requesting DTC was set. This allows the technician to re-create the conditions when a fault occurred and to verify the proper operation within these conditions.

•	Failure Records -- Contains the information at the time a diagnostic test failed and set a DTC. The failure records data is not necessarily associated with the MIL.

Engine 1 Data

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

Desired Idle - 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'sengine speed should remain close to the desired idle under the various engine loads with the engine idling.

ECT - Range -40°C-151°C (-40°F-304°F): The Engine Coolant Temperature (ECT) sensor sends 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 internal resistance as temperature changes. When the sensor is cold (internal resistance high), the PCM monitors a high voltage which it interprets 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.

IAT - Range -40°C-151°C (-40°F-304°F): The PCM converts the resistance of the Intake Air Temperature (IAT) sensor to degrees in the same manner as the ECT sensor. Intake air temp is used by the PCM to adjust fuel delivery and spark timing according to 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 engine load and speed changes. As the intake manifold pressure increases, the air density in the intake also increases and additional fuel is required.

BARO - Range 11-105 kPa, 0-5.0 Volts: The Barometric Pressure (BARO) sensor measures the change in the intake manifold pressure which results from altitude changes. This value is updated at ignition ON and also at Wide Open Throttle (WOT).

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 Oxygen Sensor (O2S 1) 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 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.

FT Index - Range 0-255 (-100% to 100%): 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%): Short Term Fuel Trim (FT) represents a short term correction to fuel delivery by the PCM in response to the amount of time the oxygen sensor voltage spends above or below the 450 mV threshold. If the oxygen sensor has mainly been below 450 mV, indicating a lean air/fuel mixture, short term fuel trim will increase to tell the PCM to add fuel. If the oxygen sensor voltage stays mainly above the threshold, the PCM will reduce fuel delivery 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. 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 Fuel 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 (IC). The PCM responds to the Knock Sensor (KS) signal.

Spark - Range 64 to -64 degrees: This is a display of the spark advance (IC) calculation which the PCM is programming in the ignition system. It computes the desired spark advance using data such as engine temperature, RPM, engine load, vehicle speed and operating mode.

KS Retard - 0-90 degrees: The Knock Sensor (KS) retard indicates the amount of spark advance (IC) the PCM is removing from in response to the Knock Sensor (KS) signal.

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 - 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 Act. Counter - Range 0-255 Counts: The Crankshaft Position (CKP) activity counter displays whether the PCM is receiving the 7X sync pulses from the ignition module. Helpful in diagnosing DTC P0335 and Cranks But Will Not Run conditions.

CMP Act. 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 Sol. - 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.

EVAP Vent Solenoid - Range Off/On: The normally open EVAP vent solenoid allows fresh outside air to the EVAP canister during purge modes. The EVAP vent solenoid also allows the PCM to pull a vacuum on the fuel tank by closing the vent solenoid.

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.

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

ECT - Range -40°C- 151°C (-40°F- 304°F): The Engine Coolant Temperature (ECT) sensor sends 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 internal resistance as temperature changes. When the sensor is cold (internal resistance high), the PCM monitors a high voltage which it interprets 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.

FC Relay - Range Off/On: The Fan Control (FC) relay is commanded by the PCM. FC relay displays the command as On or OFF.

Ignition Volts - 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 (O2S 1) voltage. The PCM controls the fuel delivery air to fuel ratio as close to 14.7:1 as possible.

GEN F Terminal - Range 0-100%: The generator F terminal is the duty cycle or load input to the PCM from the generator. As the generator load increases, the PCM will adjust idle speed accordingly.

GEN L Terminal - Range Inactive/Active: The generator L terminal indicates whether the PCM is allowing the generator to operate. The PCM can disable the generator under certain conditions to ease starting. Inactive indicates that the PCM is allowing generator operation, while active indicates that the PCM is not allowing generator operation.

TCC Brake Switch - Range Off/On: 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.

Power Enrichment - Range Off/On: The scan tool indicates when power enrichment mode is active (moderate to heavy acceleration). Helpful in diagnosing DTC P1171.

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

LOAD - Range 0-100%: Indicates engine load based on manifold absolute pressure. The higher the percentage, the more 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

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 - 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-151°C (-40°F-304°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-151°C(-40°F-304°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 engine load and speed changes. As the intake manifold pressure increases, the air density in the intake also increases and additional fuel is required.

BARO - Range 11-105 kPa, 0-5.0 Volts: 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 - 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. 1-4 - Range 0-999.9 mS: Indicates the base Pulse Width Modulation (PWM) or ON time of the indicated cylinder injector in milliseconds. When the engine load is increased, the injector pulse width will increase.

Engine Oil Level - Range Low/OK: Indicates whether the engine oil level is Low or OK. Helpful in diagnosing Table C16, Oil Level Input.

ECL - Range Low/OK: The Engine Coolant Level (ECL) is displayed as Low or OK. Indicates whether the coolant in the radiator coolant surge tank is Low or OK.

Engine Oil Pres. - Range Low/OK: The fuel pump and the engine oil pressure switch sends an input to the PCM in order to indicate whether the engine oil pressure is Low or OK.

A/C Request - Range Yes/No: Represents whether Air Conditioning (A/C) is being requested from the HVAC selector. The input is received by the Instrument Panel Cluster (IPC) and then sent over UART serial data to the PCM and finally to the scan tool over class 2 serial data.

A/C High Side - Range 0-5.0 Volts, 0-459 PSI: 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 - 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 Engaged - Range Yes/No: Cruise engaged is an input from the cruise control module to the PCM and indicates if the cruise control system is in control of vehicle speed. The PCM uses this information to change transmission shift calibrations and to turn ON an indicator lamp on the Instrument Panel Cluster (IPC) (when equipped). Helpful with diagnosing Table C17 Cruise Control Diagnosis.

Output Driver 1 - Range SHRT00000000 Open00000000 (binary display): Output driver modules are used to allow various systems to function by providing a ground circuit. The scan tool will display "0s" in each of the 8 positions when the circuitry is OK. If a 1 appears in any of the positions, then either a short or open circuit is being detected. Refer to Section C20, PCM Outputs, for further information.

Output Driver 2 - Range SHRT00000000 Open00000000 (binary display): Output driver modules are used to allow various systems to function by providing a ground circuit. The scan tool will display 0s in each of the 8 positions when the circuitry is OK. If a 1 appears in any of the positions, then either a short or open circuit is being detected. Refer to Section C20, PCM Outputs for further information.

PRNDL P, A, B, C - Range High or 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 High to Low as different combinations are met. In Park, PRNDL P and A will be Low and B and C will be High.

Trans. Range - Range Park/Reverse/Neutral/Overdrive/Drive 3/Drive 2/Low/Invalid: The scan tool displays the decoded position of the transmission range switch PRNDL inputs. This information is then sent by UART serial data to the Instrument Panel Cluster (IPC) to be displayed to the operator on the IPC. If a valid combination of inputs is not seen by the PCM, Invalid will be displayed.

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

Specific Engine EGR/EVAP Data

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 - 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-151°C (-40°F-304°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-151°C (-40°F-304°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, 0-5.0 Volts: 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 2 - Range 0-1132 mV: The Rear Heated Oxygen Sensor (HO2S 2) represents the exhaust oxygen output voltage beyond the catalytic converter. This voltage will remain inactive or appear lazy within a range of 100 mV (lean exhaust) and 900 mV (rich exhaust) when the system is operating in Closed Loop.

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 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. 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 MAP kPa change the PCM expected to see when the diagnostic ran and the actual MAP kPa change that was seen. The EGR EWMA value should always be near -3. Whenever the EGR EWMA value becomes more positive (towards 0), then the EGR system is becoming 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.

EGR Actual - 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.

Delta MAP Change - Range -20 to 20 kPa: The amount of MAP change the PCM sensed from the beginning of the diagnostic until the end. Used to calculate the difference in the actual MAP change and the expected MAP change to determine the Decel EWMA value.

EGR Decel Trip Sample Counter - Range 0 to 255 Counts: Displays the number of test that have been run for DTC P0401. Once the counter reaches 255, the number will stop until a battery disconnect or an EGR DTC has been cleared.

EVAP Solenoid - 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 Solenoid - Range ON/OFF: 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 Sensor 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.

Output Driver 1 - Range SHRT00000000 OPEN00000000 (binary display): Output driver modules are used to allow various systems to function by providing a ground circuit. The scan tool will display 0s in each of the 8 positions when the circuitry is OK. If a 1 appears in any of the positions, then either a short or open circuit is being detected. Refer to PCM Outputs for further information.

Output Driver 2 - Range SHRT00000000 OPEN00000000 (binary display): Output driver modules are used to allow various systems to function by providing a ground circuit. The scan tool will display 0s in each of the 8 positions when the circuitry is OK. If a 1 appears in any of the positions, then either a short or open circuit is being detected. Refer to PCM Outputs for further information.

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: Indicates the total number of current Diagnostic Trouble Codes (DTCs) set. Does not necessarily mean the Malfunction Indicator Lamp (MIL) is illuminated.

Specific Eng., Misfire Data

Specific Eng., O2S Data

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

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

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

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

ECT - Range -40°C- 151°C (-40°F- 304°F): The Engine Coolant Temperature (ECT) sensor sends 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 internal resistance as temperature changes. When the sensor is cold (internal resistance high), the PCM monitors a high voltage which it interprets 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.

IAT - Range -40°C- 151°C (-40°F- 304°F): The PCM converts the resistance of the Intake Air Temperature (IAT) sensor to degrees in the same manner as the ECT sensor. Intake air temp is used by the PCM to adjust fuel delivery and spark timing according to 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 engine load and speed changes. As the intake manifold pressure increases, the air density in the intake also increases and additional fuel is required.

BARO - Range 11-105 kPa, 0-5.0 Volts: The Barometric Pressure (BARO) sensor measures the change in the intake manifold pressure which results from altitude changes. This value is updated at ignition ON and also at Wide Open Throttle (WOT).

TP Sensor - Range 0-5.0 Volts: The Throttle Position (TP) sensor is used by the PCM to determine the amount of throttle demanded by the operator of the vehicle. The TP sensor will read between .36-.96 volt at idle to above 4 volts at Wide Open Throttle (WOT).

TP Angle - Range 0-100%: Throttle Position (TP) angle is computed by the PCM from the TP sensor voltage input. TP angle will auto zero to 0% at idle (TP voltage below .90volt) and read 100% at Wide Open throttle (WOT).

Fuel Trim Cell - Range 0-22: Fuel Trim Cell is dependent upon engine speed and MAP sensor readings. A plot of RPM vs. MAP is broken down into 22 cells. Fuel Trim Cell indicates which cell is currently active.

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

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

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

Lean/Rich Transition - Range 0-255 counts: The PCM counts the number of times the Oxygen Sensor (O2S 1) goes from a low voltage (lean exhaust) to a high voltage (rich exhaust) within a 100 second period.

Rich/Lean Transition - Range 0-255 counts: The PCM counts the number of times the Oxygen Sensor (O2S 1) goes from a high voltage (rich exhaust) to a low voltage (lean exhaust) within a 100 second period.

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

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

Rich/Lean to Lean/Rich Ratio 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 grams/second: The calculated air flow is a calculation based on manifold absolute pressure. The calculation is used in several diagnostics to determine when to run.

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

Loop Status - Range Open/Closed: Closed Loop is displayed indicating that the PCM is controlling fuel delivery according to the Oxygen Sensor (O2S 1) voltage as close to an air/fuel ratio of 14.7 to 1 as possible.

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

DTC, Freeze Frame Data

DTC Freeze Frame - Range #: Indicates which DTC this freeze frame information is for. Clearing out the DTCs will erase the freeze frame information. This information should be recorded or printed before clearing out any of the DTCs.

Air Fuel Ratio - Range 0:1- 25.5:1: Indicates the air fuel ratio based on Oxygen Sensor (O2S 1) inputs. The PCM uses 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 grams/second: The calculated air flow is a calculation based on the manifold absolute pressure. The calculation is used in several diagnostics to determine when to run.

ECT - Range -40°C- 151°C (-40°F- 304°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 internal resistance as the temperature changes. When the sensor is cold (internal resistance high), the PCM monitors a high voltage which it interprets as a cold engine. As the sensor warms (the internal resistance decreases), the voltage signal will decrease and the PCM will interpret the lower voltage as a warm engine.

BARO - Range 11-105 kPa, 0-5.0 Volts: The Barometric Pressure (BARO) sensor measures the change in the intake manifold pressure which results from altitude changes. This value is updated at ignition ON and also at Wide Open Throttle (WOT).

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

Short Term FT - Range 0-255 (-100% to 100%): The Short Term Fuel Trim (FT) represents a short term correction to the fuel delivery by the PCM in response to the amount of time the oxygen sensor voltage spends above or below the 450 mV threshold. If the oxygen sensor has mainly been below 450 mV, indicating a lean air/fuel mixture, 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 0-255 (-100% to 100%): The Long Term Fuel Trim (FT) is derived from the short term fuel trim value and is used for the long term correction ofthe fuel delivery. A value of 128 counts (0%) indicates that the fuel delivery requires no compensation in order to maintain a 14.7:1 air/fuel ratio. A value below 128 counts means that the fuel system is too rich and the fuel delivery is being reduced (decreased injector pulse width). A value above 128 counts indicates that a lean condition exists and the PCM is compensating.

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 engine load and speed changes. As the intake manifold pressure increases, the air density in the intake also increases and additional fuel is required.

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

Loop Status - Range Open/Closed: The Closed Loop is displayed indicating that the PCM is controlling the fuel delivery according to the Oxygen Sensor (O2S 1) voltage as close to an air/fuel ratio of 14.7 to 1 as possible.

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

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

TP Angle - Range 0-100%: Te Throttle Position (TP) angle is computed by the PCM from the TP sensor voltage input. The TP angle will auto zero to 0% at idle (TP voltage below .90 volt) and read 100% at Wide Open throttle (WOT).