For 1990-2009 cars only
A/C High Side Pressure: The scan tool displays 0.00 to 5.00 volts. This represents
the A/C refrigerant pressure sensor signal. The amount of pressure indicates
the amount of load that the A/C compressor is placing on the engine. The
powertrain control module (PCM) uses this information to adjust idle and
to control the cooling fans.
A/C Pressure Out Of Range: The scan tool displays YES or NO. YES displayed indicates that the PCM is monitoring an A/C refrigerant pressure signal voltage which is too high or too low to allow the A/C compressor clutch to engage.
A/C Request: The scan tool displays YES or NO. YES displayed indicates that the HVAC system has requested A/C compressor operation. The HVAC system sends the A/C request information to the PCM via the Class 2 serial data circuit.
Actual EGR Position: The scan tool range is 0% to 100%. This represents the actual position of the EGR pintle in percent. 0% displayed indicates a fully extended pintle (EGR valve closed).
Air Fuel Ratio: The scan tool range is 0.0 to 25.5. Air Fuel Ratio indicates the PCM commanded value. In closed loop, the air fuel ratio should normally be around 14.2 - 14.7. A lower air fuel ratio indicates a richer commanded mixture, which may be seen during Power Enrichment or TWC Protection modes. A higher air fuel ratio indicates a leaner commanded mixture. This may be seen during Decel Fuel Mode.
BARO: The scan tool range is 10 to 105 kPa / 0.00 to 5.00 volts. The barometric pressure reading is determined from the MAP sensor signal that is monitored during key up and wide-open throttle (WOT) conditions. The barometric pressure is used to adjust fuel delivery and spark advance in order to compensate for altitude changes.
Commanded A/C: The scan tool displays ON or OFF. This represents the PCM commanded state of the A/C compressor clutch relay driver circuit. The A/C compressor clutch should be engaged when Commanded A/C displays ON.
Commanded Fan 1 / Commanded Fan 2: The scan tool displays ON or OFF. This represents the PCM commanded state of the fan 1 (low speed) and fan 2 (high speed) control circuits.
Commanded Gen: The scan tool displays ON or OFF. OFF displayed indicates that the PCM has commanded the generator control circuit off.
Commanded Starter: The scan tool displays ENABLED or DISABLED. Disabled displayed indicates that the PCM has inhibited the starter relay operation. The PCM inhibits the starter relay operation if the engine is running, a correct vehicle theft deterrent (VTD) password is not received from the PASS-Key® III module, or if the starter is engaged for an extended period of time.
Cruise: The scan tool displays ENGAGED or DISENGAGED. This represents the state of the Cruise Status Input from the stepper motor cruise control (SMCC) module. Cruise should not display ENGAGED unless the vehicle is operating in cruise control.
Cruise Inhibited: The scan tool displays YES or NO. YES displayed indicates that the PCM is commanding the SMCC module to inhibit cruise control operation. YES should display with park, neutral, reverse or low gear selected.
Current Gear: The scan tool displays numbers 1, 2, 3, or 4. The PCM looks at the transaxle range position and the gear commanded by the PCM. The actual forward gear that the transaxle is in is the lower of the two because the manual valve may override the PCM commanded gear.
Decel Fuel Mode: The scan tool displays ACTIVE or INACTIVE. ACTIVE displayed indicates that the PCM has detected conditions appropriate to operate in Deceleration Fuel mode. The PCM commands Deceleration Fuel mode when a sudden decrease in throttle position is detected while the vehicle is traveling over 10 mph. While in Deceleration Fuel mode, the PCM decreases the amount of fuel delivered by entering Open Loop and decreasing the injector pulse width.
Desired EGR Position: The scan tool range is 0% to 100%. This represents the EGR pintle position that the PCM is commanding. The Desired EGR Position should stay close to the Actual EGR Position.
Desired Idle Speed: The scan tool range is 0 to 3187 RPM. This is the idle speed that is commanded by the PCM. The PCM compensates for various engine loads based upon the engine coolant temperature in order to keep the engine at the desired idle speed.
ECT: The scan tool range is -40°C to 151°C (-40°F to 304°F). The engine coolant temperature (ECT) sensor is mounted in the coolant stream. The PCM applies 5 volts to the ECT 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 signal voltage and interprets it as a cold engine. As the sensor warms (internal resistance decreases), the voltage signal decreases and the PCM interprets the lower voltage as a warm engine.
EGR Closed Valve Pintle Position: The scan tool range is 0.0 to 5.0 volts. This represents the learned voltage that the PCM uses to determine whether or not the EGR valve is fully closed (0% pintle position). If the Desired EGR Position is 0% and a difference of more than 0.4 volt between EGR Feedback and EGR Closed Valve Pintle Position is detected, DTC P1406 is set.
EGR Duty Cycle: The scan tool range is 0% to 100%. This represents the EGR valve driver pulse width modulated (PWM) signal from the PCM. A duty cycle of 0 percent indicates that no EGR flow is being commanded; a 100 percent duty cycle indicates a maximum EGR flow commanded.
EGR Feedback: The scan tool range is 0.00 to 5.00 volts. This indicates the EGR pintle position sensor signal voltage being monitored by the PCM. A low voltage indicates a fully extended pintle (closed valve). A voltage near 5 volts indicates a fully retracted pintle (open valve).
EGR Flow Test Count: The scan tool range is 0 to 255. This indicates the number of EGR flow test samples collected during the current ignition cycle. The maximum number of samples allowed is 1 during normal operation. If the PCM battery feed is disconnected or DTC P0401 is cleared, several EGR flow test samples are allowed during the next ignition cycle. This allows repair verification during a single ignition cycle.
EGR Position Error: The scan tool range is -100% to 100%. This indicates the difference between the desired EGR position and the actual EGR position currently being monitored by the PCM. If the EGR Position Error reaches an unacceptable level, DTC P0404 or P1404 is set.
Engine Load: The scan tool range is 0% to 100%. The engine load is calculated by the PCM from the engine speed and the mass air flow (MAF) sensor readings. Engine Load should increase with an increase in RPM or air flow.
Engine Oil Level: The scan tool displays OK or LOW. This indicates the oil level as determined by the engine oil level switch.
Engine Oil Pressure Switch: The scan tool displays OK or LOW. This indicates the oil pressure as determined by the engine oil pressure switch input to the PCM.
Engine Run Time: The scan tool range is 00:00:00 to 99:99:99 Hrs:Min:Sec. This indicates the time elapsed since the engine was started. If the engine is stopped, the engine run time is reset to 00:00:00.
Engine Speed: The scan tool range is 0 to 9999 RPM. Engine Speed is computed by the PCM from the 3X reference input. It should remain close to desired idle under various engine loads with the engine idling.
EVAP Canister Purge: The scan tool range is 0% to 100%. This represents the PCM commanded PWM duty cycle of the EVAP purge valve. 0% displayed indicates no purge; 100% displayed indicates full purge.
EVAP Vent Sol: The scan tool displays OPEN or CLOSED. This represents the state of the EVAP canister fresh air vent solenoid. The solenoid should be open during normal operation.
Fuel Pump: The scan tool displays ON or OFF. This indicates the PCM commanded state of the fuel pump relay control circuit.
Fuel Tank Pressure: The scan tool displays 0 to 64 in. H2O/ 0 to 5 volts. The signal from the fuel tank pressure sensor is monitored by the PCM to verify that the evaporative emissions control system is operating correctly and leaks are not present. The fuel tank pressure level is used extensively for EVAP purge control and EVAP system diagnostics.
Fuel Trim Cell: The scan tool range is 0 to 9. The fuel trim cell is dependent upon the engine speed and MAF sensor readings. A plot of RPM vs. MAF is divided into 10 cells. Fuel Trim Cell indicates which cell is currently active.
Fuel Trim Learn: The scan tool displays DISABLED or ENABLED. When conditions are appropriate for enabling long term fuel trim corrections, the scan tool displays ENABLED. This indicates that the long term fuel trim is responding to short term fuel trim. If the Fuel Trim Learn displays DISABLED, long term fuel trim does not respond to changes in short term fuel trim.
Generator PWM: The scan tool range is 0% to 100%. This represents the field terminal input from the generator. The field PWM duty cycle indicates generator output level. A higher duty cycle indicates a higher generator output. The PCM uses the generator F terminal signal to adjust the spark and the idle air control (IAC) in order to compensate for variances in engine load caused by the generator.
HO2S Sensor 1: The scan tool displays NOT READY or READY. This indicates the status of the fuel control exhaust oxygen sensor. The scan tool indicates that the exhaust oxygen sensors are ready when the PCM detects a fluctuating HO2S voltage sufficient to allow closed loop operation. This does not occur unless the exhaust oxygen sensors are warmed up.
HO2S Sensor 1: The scan tool range is 0 to 1132 mV. This represents the fuel control exhaust oxygen sensor output voltage. The reading should fluctuate constantly within a range of 10 mV (lean exhaust) to 1000 mV (rich exhaust) while operating in Closed Loop.
HO2S Sensor 2: The scan tool range is 0 to 1132 mV. This represents the output voltage of the exhaust oxygen sensor . If the catalyst is operating efficiently, the HO2S 1 signal is far more active than that produced by the HO2S 2 sensor. If the PCM detects a level of HO2S 2 activity that indicates the catalyst is no longer operating efficiently, DTC P0420 is set.
HO2S Warm-Up Sensor 1 / HO2S Warm-Up Sensor 2: The scan tool range is 00:00 to 99:99 MIN:SEC. This indicates the time to warm-up for each HO2S. The HO2S warm up time is used for the HO2S heater test. The PCM runs the heater test only after a cold start (determined by engine coolant and intake air temperature at the time of startup) and only once during an ignition cycle. When the engine is started the PCM monitors the HO2S voltage. When the HO2S voltage indicates a sufficiently active sensor, the PCM looks at how much time has elapsed since startup. If the PCM determines that too much time was required for the HO2S to become active, a DTC is set. If the engine was warm when started, HO2S Warm-Up displays the value that was stored the last time the test ran. If the information is cleared, HO2S Warm-Up displays 00:00.
HO2S XCounts: The scan tool range is 0 to 255. This indicates the number of times the HO2S 1 signal has crossed the 450 mV bias voltage during a 1 second interval. A HO2S 1 signal that almost never crosses the bias voltage could indicate a fuel trim problem, a faulty HO2S 1 circuit, or a faulty HO2S 1.
IAC Position: The scan tool range is 0 to 255. This is the commanded position of the idle air control pintle in counts. A larger number of counts means that more air is being commanded through the idle air passage. IAC Position should respond fairly quickly to changes in engine load in order to maintain the desired idle RPM.
IAT: The scan tool range is -40°C to 151°C (-40°F to 304°F). The PCM converts the resistance of the intake air temperature sensor to degrees. The PCM uses the intake air temperature (IAT) to adjust fuel delivery and spark timing according to incoming air density. The IAT is also compared to the engine coolant temperature (ECT) at startup in order to identify cold starts for the HO2S heater and the EVAP diagnostics.
Ignition 1: The scan tool range is 0 to 25.5 volts. This represents the system voltage measured by the PCM at the PCM ignition feed.
Ignition Mode: The scan tool displays BYPASS or IC. This indicates the commanded state of the Bypass signal output from the PCM. When BYPASS is displayed, the ignition control module is controlling the spark advance at a fixed 10° BTDC (Bypass mode). IC displayed indicates that the PCM has requested control of the spark advance (IC mode). The ignition control module determines the correct operating mode based on the level of voltage that the PCM applies to the ignition control module bypass circuit. The PCM provides 5 volts to the ignition control module bypass circuit when conditions are appropriate for PCM control of spark timing (IC mode). If the PCM does not apply 5 volts to the bypass circuit, or if the ignition control module does not receive the voltage, the module controls spark timing.
Injector Pulse Width: The scan tool range is 0 to 1000 msec. This indicates the amount of time the PCM is commanding each injector ON during each engine cycle. A longer injector pulse width causes more fuel to be delivered. The injector pulse width should increase with increased engine load.
Knock Retard: The scan tool range is 0.0 degrees to 25.5 degrees. This indicates the amount of spark the PCM is removing from IC spark advance in response to the signal from the knock sensors. The traction control system Desired Torque signal from the electronic brake control module (EBCM) may cause Knock Retard to display a value more than 0.0 degrees if the traction control is active.
Long Term FT: The scan tool range is -23% to 16%. Long Term FT is derived from the short term fuel trim value and represents a long-term correction of fuel delivery. A value of 0% indicates that fuel delivery requires no compensation to maintain the PCM commanded air/fuel ratio. A negative value significantly below 0% indicates that the fuel system is rich and fuel delivery is being reduced (decreased injector pulse width). A positive value significantly more than 0% indicates that a lean condition exists and the PCM is compensating by adding fuel (increased injector pulse width). Because long term fuel trim tends to follow short term fuel trim, a value in the negative range due to canister purge at idle should not be considered unusual. The PCM's maximum authority to control long term fuel trim allows a range between -23% and +16%. Fuel trim values at or near maximum authority may indicate an excessively rich or lean system.
Loop Status: The scan tool displays OPEN or CLOSED. Closed Loop indicates that the PCM is controlling fuel delivery according to oxygen sensor voltage. In Open Loop, the PCM ignores the oxygen sensor voltage and bases the amount of fuel to be delivered upon throttle position (TP) sensor, engine coolant, and MAF sensor inputs only.
MAF: The scan tool range is 0.0-512 g/s. MAF is the mass air flow input frequency converted to grams of air per second. This indicates the amount of air entering the engine.
MAF Frequency: The scan tool range is 0 to 32000 Hz. The MAF sensor input signal to the PCM is a frequency which varies from around 3000 Hz at idle to above 7000 Hz at wide-open throttle. The PCM converts this frequency signal to grams per second to be displayed on the scan tool as MAF.
MAP: The scan tool range is 10-105 kPa/ 0.00 to 4.97 Volts. The manifold absolute pressure (MAP) sensor measures the change in the intake manifold pressure from engine load, EGR flow, and speed changes. As intake manifold pressure increases, the intake vacuum decreases resulting in a higher MAP sensor voltage and kPa readings. The MAP sensor signal is used to monitor the intake manifold pressure changes during the EGR flow test, to update the BARO reading, and as an enabling factor for many of the diagnostics.
MIL: The scan tool displays ON or OFF. This indicates the PCM commanded state of the malfunction indicator lamp (MIL).
Misfire Current Cyl #1 / Misfire Current Cyl #2 / Misfire Current Cyl #3 / Misfire Current Cyl #4 / Misfire Current Cyl #5 / Misfire Current Cyl #6: The scan tool range is 0 to 198 counts. The Misfire Current counters indicate the number of cylinder firing events detected as possible misfires on each cylinder during the last 200 crankshaft revolutions. The number that the counters display are twice the actual number of misfire events detected. The counters may normally display some activity, but the activity should be very low and nearly equal for all the cylinders.
Misfire History Cyl #1 / Misfire History Cyl #2 / Misfire History Cyl #3 / Misfire History Cyl #4 / Misfire History Cyl #5 / Misfire History Cyl #6: The scan tool range is 0 to 65535 counts. The Misfire History counters indicate the total level of misfire detected on each cylinder. The number that the counters display are twice the actual number of misfire events detected. The Misfire History counters do not update or show any activity until a misfire DTC (P0300) has become active. The Misfire History counters are updated every time a 200 crankshaft revolution misfire test failure is detected.
Misfiring Cylinder (Primary) / Misfiring Cylinder (Secondary): The scan tool displays 0 or Cylinder #. If a misfire is being detected, Misfiring Cylinder displays the misfiring cylinder number(s).
Power Enrichment: The scan tool displays ACTIVE or INACTIVE. ACTIVE displayed indicates that the PCM has detected the conditions appropriate to operate in Power Enrichment mode. The PCM commands Power Enrichment mode when a large increase in throttle position and load is detected. While in Power Enrichment, the PCM increases 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 occurring during acceleration.
Rich/Lean: The scan tool displays RICH or LEAN. This indicates whether the oxygen sensor voltage is more than a 600 mV threshold voltage (rich) or less than a 300 mV threshold voltage (lean). This should change constantly while in closed loop, indicating that the PCM is controlling the air/fuel mixture properly.
Short Term FT: The scan tool range is -11% to 20%. The short term fuel trim represents a short-term correction to the fuel delivery by the PCM in response to the amount of time the fuel control oxygen sensor voltage spends above or below the 450 mV threshold. If the oxygen sensor voltage has mainly remained less than 450 mV, indicating a lean air/fuel mixture, short term fuel trim increases into the positive range above 0% and the PCM adds fuel. If the oxygen sensor voltage stays mainly above the threshold, short term fuel trim decreases below 0% into the negative range while the PCM reduces fuel delivery in order to compensate for the indicated rich condition. Under certain conditions, such as extended idle and high ambient temperatures, canister purge may cause Short Term Fuel Trim to read in the negative range during normal operation. The PCM's maximum authority to control fuel trim allows a range between -11% and +20%. Fuel trim values at maximum authority may indicate an excessively rich or lean system.
Spark: The scan tool range is -64 degrees to 64 degrees. This displays the spark timing being commanded by the PCM on the IC circuit. A negative (-) value indicates degrees before top dead center (BTDC) or spark advance. A positive value indicates degrees after top dead center (ATDC) or spark retard. Because the ignition control module sets spark advance at a fixed value of 10° BTDC while operating in Bypass mode, the displayed Spark advance only reflects the true spark timing when the PCM has commanded IC mode.
Start-Up ECT: The scan tool range is -40°C to 151°C (-40°F to 304°F). This indicates the engine coolant temperature (ECT) at the time that the vehicle was started. This is used by the HO2S diagnostic to determine if the last startup was a cold start.
Start-Up IAT: The scan tool range is -40°C to 151°C, (-40°F to 304°F) . This indicates the intake air temperature at the time that the vehicle was started. This is used by the HO2S diagnostic to determine if the last startup was a cold start.
Throttle At Idle: The scan tool displays YES or NO. This indicates whether the TP angle being monitored by the PCM is at 0%.
Total Misfire Current Count: The scan tool range is 0 to 99. This indicates the total number of cylinder firing events that were detected as being misfires during the last 200 crankshaft revolution sample period.
Total Misfire Failures Since First Fail: The scan tool range is 0 to 65535 counts. This indicates the number of 200 crankshaft revolution sample periods during which the level of misfire was sufficiently high to report a failure.
Total Misfire Passes Since First Fail: The scan tool range is 0 to 65535 Counts. Indicates the number of 200 crankshaft revolution sample periods during which the level of misfire was sufficiently low to report a pass.
TP Angle: The scan tool range is 0% to 100%. TP Angle is computed by the PCM from the TP sensor voltage. TP Angle should display 0% at idle and 100% at wide open throttle.
TP Sensor: The scan tool range is 0.00 to 5.00 volts. The voltage being monitored by the PCM on the TP sensor signal circuit.
Transmission Range: The scan tool displays INVALID, PARK/NEUTRAL, REVERSE, DRIVE 4, DRIVE 3, DRIVE 2, or LOW. Transmission Range represents the decoded status of the 4 inputs from the transaxle range switch assembly. The combination of transaxle range inputs indicates the position of the transaxle manual valve.
TR Switch P / A / B / C: The scan tool displays HIGH or LOW. The TR Switch P / A / B / C display represents the states of the 4 inputs from the transaxle range switch. HIGH displayed indicates a B+ voltage signal being monitored at the PCM, LOW displayed indicates a grounded input signal. The combination of transaxle range inputs indicates the position of the transaxle manual valve.
TWC Diagnostic: The scan tool displays ENABLED or DISABLED. ENABLED displayed indicates that MAF, HO2S, ECT, or VSS DTCs that would disable the TWC diagnostic are not present.
TWC Monitor Test Counter: The scan tool range is 0-49. The TWC monitor test counter increments while the TWC system diagnostic test is running and taking samples. When the TWC Monitor Test Counter reaches 49, the PCM updates the TWC diagnostic statistical filter. At this point, the TWC Monitor Test Counter resets to 0 and begins incrementing again. The TWC Monitor Test Counter is most useful when verifying a 3-way catalytic converter replacement or any repair associated with the DTC P0420 diagnostic table.
TWC Protection: The scan tool displays ACTIVE or INACTIVE. ACTIVE displayed indicates that the PCM has detected the conditions appropriate to operate in TWC Protection mode. This determination is based upon the engine load and the engine coolant temperature. While in TWC Protection, the PCM decreases the air/fuel ratio to a value that depends upon the MAF (higher MAF = lower air/fuel ratio).
Vehicle Speed: The scan tool range is 0-255 km/h, 0-155 mph. The vehicle speed sensor (VSS) signal is converted into mph and km/h for display.
A/C Pressure Out Of Range: The scan tool displays YES or NO. YES displayed indicates that the PCM is monitoring an A/C refrigerant pressure signal voltage which is too high or too low to allow the A/C compressor clutch to engage.
A/C Request: The scan tool displays YES or NO. YES displayed indicates that the HVAC system has requested A/C compressor operation. The HVAC system sends the A/C request information to the PCM via the Class 2 serial data circuit.
Actual EGR Position: The scan tool range is 0% to 100%. This represents the actual position of the EGR pintle in percent. 0% displayed indicates a fully extended pintle (EGR valve closed).
Air Fuel Ratio: The scan tool range is 0.0 to 25.5. Air Fuel Ratio indicates the PCM commanded value. In closed loop, the air fuel ratio should normally be around 14.2 - 14.7. A lower air fuel ratio indicates a richer commanded mixture, which may be seen during Power Enrichment or TWC Protection modes. A higher air fuel ratio indicates a leaner commanded mixture. This may be seen during Decel Fuel Mode.
BARO: The scan tool range is 10 to 105 kPa / 0.00 to 5.00 volts. The barometric pressure reading is determined from the MAP sensor signal that is monitored during key up and wide-open throttle (WOT) conditions. The barometric pressure is used to adjust fuel delivery and spark advance in order to compensate for altitude changes.
Commanded A/C: The scan tool displays ON or OFF. This represents the PCM commanded state of the A/C compressor clutch relay driver circuit. The A/C compressor clutch should be engaged when Commanded A/C displays ON.
Commanded Fan 1 / Commanded Fan 2: The scan tool displays ON or OFF. This represents the PCM commanded state of the fan 1 (low speed) and fan 2 (high speed) control circuits.
Commanded Gen: The scan tool displays ON or OFF. OFF displayed indicates that the PCM has commanded the generator control circuit off.
Commanded Starter: The scan tool displays ENABLED or DISABLED. Disabled displayed indicates that the PCM has inhibited the starter relay operation. The PCM inhibits the starter relay operation if the engine is running, a correct vehicle theft deterrent (VTD) password is not received from the PASS-Key® III module, or if the starter is engaged for an extended period of time.
Cruise: The scan tool displays ENGAGED or DISENGAGED. This represents the state of the Cruise Status Input from the stepper motor cruise control (SMCC) module. Cruise should not display ENGAGED unless the vehicle is operating in cruise control.
Cruise Inhibited: The scan tool displays YES or NO. YES displayed indicates that the PCM is commanding the SMCC module to inhibit cruise control operation. YES should display with park, neutral, reverse or low gear selected.
Current Gear: The scan tool displays numbers 1, 2, 3, or 4. The PCM looks at the transaxle range position and the gear commanded by the PCM. The actual forward gear that the transaxle is in is the lower of the two because the manual valve may override the PCM commanded gear.
Decel Fuel Mode: The scan tool displays ACTIVE or INACTIVE. ACTIVE displayed indicates that the PCM has detected conditions appropriate to operate in Deceleration Fuel mode. The PCM commands Deceleration Fuel mode when a sudden decrease in throttle position is detected while the vehicle is traveling over 10 mph. While in Deceleration Fuel mode, the PCM decreases the amount of fuel delivered by entering Open Loop and decreasing the injector pulse width.
Desired EGR Position: The scan tool range is 0% to 100%. This represents the EGR pintle position that the PCM is commanding. The Desired EGR Position should stay close to the Actual EGR Position.
Desired Idle Speed: The scan tool range is 0 to 3187 RPM. This is the idle speed that is commanded by the PCM. The PCM compensates for various engine loads based upon the engine coolant temperature in order to keep the engine at the desired idle speed.
ECT: The scan tool range is -40°C to 151°C (-40°F to 304°F). The engine coolant temperature (ECT) sensor is mounted in the coolant stream. The PCM applies 5 volts to the ECT 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 signal voltage and interprets it as a cold engine. As the sensor warms (internal resistance decreases), the voltage signal decreases and the PCM interprets the lower voltage as a warm engine.
EGR Closed Valve Pintle Position: The scan tool range is 0.0 to 5.0 volts. This represents the learned voltage that the PCM uses to determine whether or not the EGR valve is fully closed (0% pintle position). If the Desired EGR Position is 0% and a difference of more than 0.4 volt between EGR Feedback and EGR Closed Valve Pintle Position is detected, DTC P1406 is set.
EGR Duty Cycle: The scan tool range is 0% to 100%. This represents the EGR valve driver pulse width modulated (PWM) signal from the PCM. A duty cycle of 0 percent indicates that no EGR flow is being commanded; a 100 percent duty cycle indicates a maximum EGR flow commanded.
EGR Feedback: The scan tool range is 0.00 to 5.00 volts. This indicates the EGR pintle position sensor signal voltage being monitored by the PCM. A low voltage indicates a fully extended pintle (closed valve). A voltage near 5 volts indicates a fully retracted pintle (open valve).
EGR Flow Test Count: The scan tool range is 0 to 255. This indicates the number of EGR flow test samples collected during the current ignition cycle. The maximum number of samples allowed is 1 during normal operation. If the PCM battery feed is disconnected or DTC P0401 is cleared, several EGR flow test samples are allowed during the next ignition cycle. This allows repair verification during a single ignition cycle.
EGR Position Error: The scan tool range is -100% to 100%. This indicates the difference between the desired EGR position and the actual EGR position currently being monitored by the PCM. If the EGR Position Error reaches an unacceptable level, DTC P0404 or P1404 is set.
Engine Load: The scan tool range is 0% to 100%. The engine load is calculated by the PCM from the engine speed and the mass air flow (MAF) sensor readings. Engine Load should increase with an increase in RPM or air flow.
Engine Oil Level: The scan tool displays OK or LOW. This indicates the oil level as determined by the engine oil level switch.
Engine Oil Pressure Switch: The scan tool displays OK or LOW. This indicates the oil pressure as determined by the engine oil pressure switch input to the PCM.
Engine Run Time: The scan tool range is 00:00:00 to 99:99:99 Hrs:Min:Sec. This indicates the time elapsed since the engine was started. If the engine is stopped, the engine run time is reset to 00:00:00.
Engine Speed: The scan tool range is 0 to 9999 RPM. Engine Speed is computed by the PCM from the 3X reference input. It should remain close to desired idle under various engine loads with the engine idling.
EVAP Canister Purge: The scan tool range is 0% to 100%. This represents the PCM commanded PWM duty cycle of the EVAP purge valve. 0% displayed indicates no purge; 100% displayed indicates full purge.
EVAP Vent Sol: The scan tool displays OPEN or CLOSED. This represents the state of the EVAP canister fresh air vent solenoid. The solenoid should be open during normal operation.
Fuel Pump: The scan tool displays ON or OFF. This indicates the PCM commanded state of the fuel pump relay control circuit.
Fuel Tank Pressure: The scan tool displays 0 to 64 in. H2O/ 0 to 5 volts. The signal from the fuel tank pressure sensor is monitored by the PCM to verify that the evaporative emissions control system is operating correctly and leaks are not present. The fuel tank pressure level is used extensively for EVAP purge control and EVAP system diagnostics.
Fuel Trim Cell: The scan tool range is 0 to 9. The fuel trim cell is dependent upon the engine speed and MAF sensor readings. A plot of RPM vs. MAF is divided into 10 cells. Fuel Trim Cell indicates which cell is currently active.
Fuel Trim Learn: The scan tool displays DISABLED or ENABLED. When conditions are appropriate for enabling long term fuel trim corrections, the scan tool displays ENABLED. This indicates that the long term fuel trim is responding to short term fuel trim. If the Fuel Trim Learn displays DISABLED, long term fuel trim does not respond to changes in short term fuel trim.
Generator PWM: The scan tool range is 0% to 100%. This represents the field terminal input from the generator. The field PWM duty cycle indicates generator output level. A higher duty cycle indicates a higher generator output. The PCM uses the generator F terminal signal to adjust the spark and the idle air control (IAC) in order to compensate for variances in engine load caused by the generator.
HO2S Sensor 1: The scan tool displays NOT READY or READY. This indicates the status of the fuel control exhaust oxygen sensor. The scan tool indicates that the exhaust oxygen sensors are ready when the PCM detects a fluctuating HO2S voltage sufficient to allow closed loop operation. This does not occur unless the exhaust oxygen sensors are warmed up.
HO2S Sensor 1: The scan tool range is 0 to 1132 mV. This represents the fuel control exhaust oxygen sensor output voltage. The reading should fluctuate constantly within a range of 10 mV (lean exhaust) to 1000 mV (rich exhaust) while operating in Closed Loop.
HO2S Sensor 2: The scan tool range is 0 to 1132 mV. This represents the output voltage of the exhaust oxygen sensor . If the catalyst is operating efficiently, the HO2S 1 signal is far more active than that produced by the HO2S 2 sensor. If the PCM detects a level of HO2S 2 activity that indicates the catalyst is no longer operating efficiently, DTC P0420 is set.
HO2S Warm-Up Sensor 1 / HO2S Warm-Up Sensor 2: The scan tool range is 00:00 to 99:99 MIN:SEC. This indicates the time to warm-up for each HO2S. The HO2S warm up time is used for the HO2S heater test. The PCM runs the heater test only after a cold start (determined by engine coolant and intake air temperature at the time of startup) and only once during an ignition cycle. When the engine is started the PCM monitors the HO2S voltage. When the HO2S voltage indicates a sufficiently active sensor, the PCM looks at how much time has elapsed since startup. If the PCM determines that too much time was required for the HO2S to become active, a DTC is set. If the engine was warm when started, HO2S Warm-Up displays the value that was stored the last time the test ran. If the information is cleared, HO2S Warm-Up displays 00:00.
HO2S XCounts: The scan tool range is 0 to 255. This indicates the number of times the HO2S 1 signal has crossed the 450 mV bias voltage during a 1 second interval. A HO2S 1 signal that almost never crosses the bias voltage could indicate a fuel trim problem, a faulty HO2S 1 circuit, or a faulty HO2S 1.
IAC Position: The scan tool range is 0 to 255. This is the commanded position of the idle air control pintle in counts. A larger number of counts means that more air is being commanded through the idle air passage. IAC Position should respond fairly quickly to changes in engine load in order to maintain the desired idle RPM.
IAT: The scan tool range is -40°C to 151°C (-40°F to 304°F). The PCM converts the resistance of the intake air temperature sensor to degrees. The PCM uses the intake air temperature (IAT) to adjust fuel delivery and spark timing according to incoming air density. The IAT is also compared to the engine coolant temperature (ECT) at startup in order to identify cold starts for the HO2S heater and the EVAP diagnostics.
Ignition 1: The scan tool range is 0 to 25.5 volts. This represents the system voltage measured by the PCM at the PCM ignition feed.
Ignition Mode: The scan tool displays BYPASS or IC. This indicates the commanded state of the Bypass signal output from the PCM. When BYPASS is displayed, the ignition control module is controlling the spark advance at a fixed 10° BTDC (Bypass mode). IC displayed indicates that the PCM has requested control of the spark advance (IC mode). The ignition control module determines the correct operating mode based on the level of voltage that the PCM applies to the ignition control module bypass circuit. The PCM provides 5 volts to the ignition control module bypass circuit when conditions are appropriate for PCM control of spark timing (IC mode). If the PCM does not apply 5 volts to the bypass circuit, or if the ignition control module does not receive the voltage, the module controls spark timing.
Injector Pulse Width: The scan tool range is 0 to 1000 msec. This indicates the amount of time the PCM is commanding each injector ON during each engine cycle. A longer injector pulse width causes more fuel to be delivered. The injector pulse width should increase with increased engine load.
Knock Retard: The scan tool range is 0.0 degrees to 25.5 degrees. This indicates the amount of spark the PCM is removing from IC spark advance in response to the signal from the knock sensors. The traction control system Desired Torque signal from the electronic brake control module (EBCM) may cause Knock Retard to display a value more than 0.0 degrees if the traction control is active.
Long Term FT: The scan tool range is -23% to 16%. Long Term FT is derived from the short term fuel trim value and represents a long-term correction of fuel delivery. A value of 0% indicates that fuel delivery requires no compensation to maintain the PCM commanded air/fuel ratio. A negative value significantly below 0% indicates that the fuel system is rich and fuel delivery is being reduced (decreased injector pulse width). A positive value significantly more than 0% indicates that a lean condition exists and the PCM is compensating by adding fuel (increased injector pulse width). Because long term fuel trim tends to follow short term fuel trim, a value in the negative range due to canister purge at idle should not be considered unusual. The PCM's maximum authority to control long term fuel trim allows a range between -23% and +16%. Fuel trim values at or near maximum authority may indicate an excessively rich or lean system.
Loop Status: The scan tool displays OPEN or CLOSED. Closed Loop indicates that the PCM is controlling fuel delivery according to oxygen sensor voltage. In Open Loop, the PCM ignores the oxygen sensor voltage and bases the amount of fuel to be delivered upon throttle position (TP) sensor, engine coolant, and MAF sensor inputs only.
MAF: The scan tool range is 0.0-512 g/s. MAF is the mass air flow input frequency converted to grams of air per second. This indicates the amount of air entering the engine.
MAF Frequency: The scan tool range is 0 to 32000 Hz. The MAF sensor input signal to the PCM is a frequency which varies from around 3000 Hz at idle to above 7000 Hz at wide-open throttle. The PCM converts this frequency signal to grams per second to be displayed on the scan tool as MAF.
MAP: The scan tool range is 10-105 kPa/ 0.00 to 4.97 Volts. The manifold absolute pressure (MAP) sensor measures the change in the intake manifold pressure from engine load, EGR flow, and speed changes. As intake manifold pressure increases, the intake vacuum decreases resulting in a higher MAP sensor voltage and kPa readings. The MAP sensor signal is used to monitor the intake manifold pressure changes during the EGR flow test, to update the BARO reading, and as an enabling factor for many of the diagnostics.
MIL: The scan tool displays ON or OFF. This indicates the PCM commanded state of the malfunction indicator lamp (MIL).
Misfire Current Cyl #1 / Misfire Current Cyl #2 / Misfire Current Cyl #3 / Misfire Current Cyl #4 / Misfire Current Cyl #5 / Misfire Current Cyl #6: The scan tool range is 0 to 198 counts. The Misfire Current counters indicate the number of cylinder firing events detected as possible misfires on each cylinder during the last 200 crankshaft revolutions. The number that the counters display are twice the actual number of misfire events detected. The counters may normally display some activity, but the activity should be very low and nearly equal for all the cylinders.
Misfire History Cyl #1 / Misfire History Cyl #2 / Misfire History Cyl #3 / Misfire History Cyl #4 / Misfire History Cyl #5 / Misfire History Cyl #6: The scan tool range is 0 to 65535 counts. The Misfire History counters indicate the total level of misfire detected on each cylinder. The number that the counters display are twice the actual number of misfire events detected. The Misfire History counters do not update or show any activity until a misfire DTC (P0300) has become active. The Misfire History counters are updated every time a 200 crankshaft revolution misfire test failure is detected.
Misfiring Cylinder (Primary) / Misfiring Cylinder (Secondary): The scan tool displays 0 or Cylinder #. If a misfire is being detected, Misfiring Cylinder displays the misfiring cylinder number(s).
Power Enrichment: The scan tool displays ACTIVE or INACTIVE. ACTIVE displayed indicates that the PCM has detected the conditions appropriate to operate in Power Enrichment mode. The PCM commands Power Enrichment mode when a large increase in throttle position and load is detected. While in Power Enrichment, the PCM increases 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 occurring during acceleration.
Rich/Lean: The scan tool displays RICH or LEAN. This indicates whether the oxygen sensor voltage is more than a 600 mV threshold voltage (rich) or less than a 300 mV threshold voltage (lean). This should change constantly while in closed loop, indicating that the PCM is controlling the air/fuel mixture properly.
Short Term FT: The scan tool range is -11% to 20%. The short term fuel trim represents a short-term correction to the fuel delivery by the PCM in response to the amount of time the fuel control oxygen sensor voltage spends above or below the 450 mV threshold. If the oxygen sensor voltage has mainly remained less than 450 mV, indicating a lean air/fuel mixture, short term fuel trim increases into the positive range above 0% and the PCM adds fuel. If the oxygen sensor voltage stays mainly above the threshold, short term fuel trim decreases below 0% into the negative range while the PCM reduces fuel delivery in order to compensate for the indicated rich condition. Under certain conditions, such as extended idle and high ambient temperatures, canister purge may cause Short Term Fuel Trim to read in the negative range during normal operation. The PCM's maximum authority to control fuel trim allows a range between -11% and +20%. Fuel trim values at maximum authority may indicate an excessively rich or lean system.
Spark: The scan tool range is -64 degrees to 64 degrees. This displays the spark timing being commanded by the PCM on the IC circuit. A negative (-) value indicates degrees before top dead center (BTDC) or spark advance. A positive value indicates degrees after top dead center (ATDC) or spark retard. Because the ignition control module sets spark advance at a fixed value of 10° BTDC while operating in Bypass mode, the displayed Spark advance only reflects the true spark timing when the PCM has commanded IC mode.
Start-Up ECT: The scan tool range is -40°C to 151°C (-40°F to 304°F). This indicates the engine coolant temperature (ECT) at the time that the vehicle was started. This is used by the HO2S diagnostic to determine if the last startup was a cold start.
Start-Up IAT: The scan tool range is -40°C to 151°C, (-40°F to 304°F) . This indicates the intake air temperature at the time that the vehicle was started. This is used by the HO2S diagnostic to determine if the last startup was a cold start.
Throttle At Idle: The scan tool displays YES or NO. This indicates whether the TP angle being monitored by the PCM is at 0%.
Total Misfire Current Count: The scan tool range is 0 to 99. This indicates the total number of cylinder firing events that were detected as being misfires during the last 200 crankshaft revolution sample period.
Total Misfire Failures Since First Fail: The scan tool range is 0 to 65535 counts. This indicates the number of 200 crankshaft revolution sample periods during which the level of misfire was sufficiently high to report a failure.
Total Misfire Passes Since First Fail: The scan tool range is 0 to 65535 Counts. Indicates the number of 200 crankshaft revolution sample periods during which the level of misfire was sufficiently low to report a pass.
TP Angle: The scan tool range is 0% to 100%. TP Angle is computed by the PCM from the TP sensor voltage. TP Angle should display 0% at idle and 100% at wide open throttle.
TP Sensor: The scan tool range is 0.00 to 5.00 volts. The voltage being monitored by the PCM on the TP sensor signal circuit.
Transmission Range: The scan tool displays INVALID, PARK/NEUTRAL, REVERSE, DRIVE 4, DRIVE 3, DRIVE 2, or LOW. Transmission Range represents the decoded status of the 4 inputs from the transaxle range switch assembly. The combination of transaxle range inputs indicates the position of the transaxle manual valve.
TR Switch P / A / B / C: The scan tool displays HIGH or LOW. The TR Switch P / A / B / C display represents the states of the 4 inputs from the transaxle range switch. HIGH displayed indicates a B+ voltage signal being monitored at the PCM, LOW displayed indicates a grounded input signal. The combination of transaxle range inputs indicates the position of the transaxle manual valve.
TWC Diagnostic: The scan tool displays ENABLED or DISABLED. ENABLED displayed indicates that MAF, HO2S, ECT, or VSS DTCs that would disable the TWC diagnostic are not present.
TWC Monitor Test Counter: The scan tool range is 0-49. The TWC monitor test counter increments while the TWC system diagnostic test is running and taking samples. When the TWC Monitor Test Counter reaches 49, the PCM updates the TWC diagnostic statistical filter. At this point, the TWC Monitor Test Counter resets to 0 and begins incrementing again. The TWC Monitor Test Counter is most useful when verifying a 3-way catalytic converter replacement or any repair associated with the DTC P0420 diagnostic table.
TWC Protection: The scan tool displays ACTIVE or INACTIVE. ACTIVE displayed indicates that the PCM has detected the conditions appropriate to operate in TWC Protection mode. This determination is based upon the engine load and the engine coolant temperature. While in TWC Protection, the PCM decreases the air/fuel ratio to a value that depends upon the MAF (higher MAF = lower air/fuel ratio).
Vehicle Speed: The scan tool range is 0-255 km/h, 0-155 mph. The vehicle speed sensor (VSS) signal is converted into mph and km/h for display.
