Scan Tool Data Definitions Part 2
Part 2HO2S SEN. 1: Scan Tool Range 0 to 1132 mV. Represents the fuel control exhaust oxygen sensor output voltage. Should fluctuate constantly within a range between 10 mV (lean exhaust) and 1000 Mv (rich exhaust) while operating in Closed Loop.
HO2S SEN. 1: Scan Tool Displays NOT READY or READY.
Indicates the status of the fuel control exhaust oxygen sensor. The scan tool will indicate that the exhaust oxygen sensors are ready when the PCM detects a fluctuating HO2S voltage sufficient to allow closed loop operation. This will not occur unless the exhaust oxygen sensors are warmed up.
HO2S SEN. 2: Scan Tool Range 0 to 1132 mV. Represents the catalyst monitor exhaust oxygen sensor output voltage. If the catalyst is operating efficiently, the HO2S 1 signal will be 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 will be set.
HO2S WARM-UP SENSOR 1 / HO2S WARM-UP SENSOR 2: Scan Tool Range 00:00 to 99:99 MIN:SEC.
Indicates time to warm-up for each HO2S. The HO2S warm up time is used for the HO2S heater test. The PCM will run 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 will monitor 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 will set. If the engine was warm when started, HO2S Warm-Up will display the value that was stored last time the test ran. If info has been cleared, HO2S Warm-Up will display 00:00.
HO2S XCOUNTS: Scan Tool Range 0 to 255. 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: Range 0 to 255.
Displays 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 to maintain desired idle RPM.
IAT: Scan Tool Range -40°°C to 151°C (-40°F to 304°F)
The PCM converts the resistance of the intake air temperature sensor to degrees. Intake Air Temperature (IAT) is used by the PCM to adjust fuel delivery and spark timing according to incoming air density.
IDLE SPEED ERROR: Range 0 to 12800 RPM. The displayed value is the difference between the PCM commanded idle speed (Desired Idle) and the actual Engine Speed.
IGNITION 1: Scan Tool Range 0 to 25.5 Volts. This represents the system voltage measured by the PCM at its ignition feed.
Ignition Mode: Scan Tool Displays BYPASS or IC. Indicates the commanded state of the Bypass signal output from the PCM. When BYPASS is displayed, the ignition control module is keeping the spark advance at a fixed 10 BTDC. IC displayed indicates that the PCM has signaled the ignition module that the PCM is going to control the spark advance (IC mode). The ignition control module determines the correct operating mode based on the level of voltage that the PCM sends to the ignition control module on the Bypass circuit. The PCM provides 5 volts to the ignition control module Bypass circuit if the PCM is going to control spark timing (IC mode). If the PCM does not turn ON the 5 volts, or if the ignition control module does not receive it, the module will control of spark timing (Bypass mode).
INJECTOR PULSE WIDTH: Scan Tool Range 0 to 1000 msec.
Indicates the amount of time the PCM is commanding each injector ON during each engine cycle. A longer injector pulse width will cause more fuel to be delivered. Injector Pulse Width should increase with increased engine load.
KNOCK RETARD: Scan Tool Range 0.0°, to 25.5°. 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 EBTCM may cause Knock Retard to display a value greater than 0.0° if Traction Control is active.
KS ACTIVE COUNTER: Scan Tool Range 0255. An incrementing counter indicates that detonation is currently being detected.
KS MINIMUM LEARNED NOISE: Scan Tool Range 0.0 to 5.0 Volts.
Indicates the minimum level that the PCM has detected on the noise channel while the noise level was being learned. If a noise channel voltage is detected below the minimum acceptable learned noise, a problem is indicated.
KS NOISE CHANNEL: Scan Tool Range 0.0 to 5.0 Volts.
Indicates the current voltage level being monitored on the KS noise channel. The PCM determines whether knock is occurring by monitoring the signal level on the KS circuit. The noise channel allows the PCM to diagnose the KS module and the knock sensor(s) by indicating the amount of normal engine mechanical noise present. Normal engine noise varies depending on engine speed and load.
LONG TERM FUEL TRIM: Scan Tool Range -23% to 16%.
Long Term Fuel Trim 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 greater 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 PCMs maximum authority to control long term fuel trim allows a range between -23% and +16%. Fuel trim values at maximum authority may indicate an excessively rich or lean system.
LOOP STATUS: 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 on TP sensor, engine coolant, and MAF sensor inputs only.
LOW OIL LAMP: Scan Tool Displays ON or OFF. Indicates the PCM commanded state of the low engine oil level lamp.
MAF: Scan Tool Range 0.0-512 gm/s. MAF (Mass Air Flow) is the MAF Input Frequency converted to grams of air per second. This indicates the amount of air entering the engine.
MAF INPUT FREQUENCY: Scan Tool Range 0 to 32000 Hz.
The Mass Air Flow 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 as Mass Air Flow.
MAP: Scan Tool Range 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, intake vacuum decreases resulting in a higher MAP sensor voltage and kPa reading. The MAP sensor signal is used to monitor intake manifold pressure changes during the EGR flow test, to update the BARO reading, and as an enabling factor for several of the diagnostics.
MIL: Scan Tool Displays ON or OFF. Indicates the PCM commanded state of the Malfunction Indicator Lamp.
MISFIRE CURRENT CYL #1 - #6: Scan Tool Range 0 to 196 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 - #6: Scan Tool Range 0 to 65535 Counts.
The Misfire History counters indicate the total level of misfire that has been detected on each cylinder. The number that the counters display are twice the actual number of misfire events detected. The Misfire History counters will not update or show any activity until a misfire DTC (P0300) has become active. The Misfire History counters will be updated every time a 200 crankshaft revolution misfire test failure is detected.
MISFIRING CYLINDER (PRIMARY) / MISFIRING CYLINDER (SECONDARY) SCAN TOOL DISPLAYS 0 OR CYLINDER #.
If a misfire is being detected, Misfiring Cylinder displays the misfiring cylinder number(s).
OIL LIFE RESET: Scan Tool Displays Released or Pressed
Indicates the state of the Oil Life Monitor Reset switch. Engine Oil Life will be reset to 100% when the Oil Life Monitor Reset switch is pressed.
PARK/NEUTRAL POS: Scan Tool Displays P-N or R-DL Indicates the status of the Park/Neutral Position switch PCM input.
POWER ENRICHMENT: Scan Tool Displays ACTIVE or 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 occurring during acceleration.
Rich/Lean: Scan Tool Displays RICH or LEAN. Indicates whether oxygen sensor voltage is greater than a 600 mV threshold voltage (rich) or less than a 300 mV threshold voltage (lean). Should change constantly while in closed loop, indicating that the PCM is controlling the air/fuel mixture properly.
SHORT TERM FUEL TRIM: Scan Tool Range -11% to 20%.
Short Term Fuel Trim represents a short-term correction to 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 will increase into the positive range above 0% and the PCM will add fuel. If the oxygen sensor voltage stays mainly above the threshold, short term fuel trim will decrease below 0% into the negative range while the PCM reduces fuel delivery 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 PCMs 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: Scan Tool Range -64°. to 64°: 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 true spark timing when the PCM has commanded IC mode.
START-UP ECT: Scan Tool Range -40°C to 151°C (-40°F to 304°F. Indicates the Engine Coolant Temperature at the time that the vehicle was started. Used by the HO2S diagnostic to determine if the last startup was a cold start.
START-UP IAT: Scan Tool Range -40°C to 151°C (-40°F to 304°F. Indicates the Intake Air Temperature at the time that the vehicle was started. Used by the HO2S diagnostic to determine if the last startup was a cold start.
SUPERCHARGER BOOST: Scan Tool Range 0% to 100%.
Represents the amount of manifold boost pressure commanded by the PCM. 100% displayed indicates full boost commanded.
THROTTLE AT IDLE: Scan Tool Displays YES or NO. Indicates whether the TP Angle being monitored by the PCM is at 0% when the throttle is closed. Refer to DTC P0121 if TP sensor angle is not 0% with the throttle closed.
TOTAL MISFIRE CURRENT COUNT:Scan Tool Range 0 to 99.
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: Scan Tool Range 0 to 65535 Counts.
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: Scan Tool Range 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: Scan Tool Range 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: Scan Tool Range 0.00 to 5.00 Volts. The voltage being monitored by the PCM on the TP sensor signal circuit.
TRACTION CONTROL: Scan Tool Displays ACTIVE or INACTIVE.
ACTIVE displayed indicates that the traction control system is taking action to reduce drive wheel slippage.
TRACTION CONTROL DESIRED TORQUE: Scan Tool Range 0% to 100%.
Represents the PWM signal from the Electronic Brake and Traction Control Module. The EBTCM reduces the Traction Control Desired Torque signal pulse width when a drive wheel slippage situation is detected. The PCM monitors the Traction Control Desired Torque signal and reduces drive wheel slippage as necessary by retarding spark timing, decreasing boost sol. PWM, or increasing air/fuel ratio. The PCM can also turn OFF up to three fuel injectors if the Traction Control Desired Torque signal indicates a large enough amount of drive wheel slippage. A problem with the Traction Control Desired Torque signal should cause DTC P1571 to set.
TRACTION CONTROL TORQUE: Scan Tool Range 0% to 100%.
Represents the PWM signal which indicates the percent of available torque the engine is delivering to the drive wheels. The EBTCM monitors the Traction Control Torque signal to ensure that the PCM is responding properly to the Traction Control Desired Torque signal.
TRANSMISSION RANGE: Scan Tool Displays INVALID,PARK / NEUTRAL, REVERSE, DRIVE 4, DRIVE 3, DRIVE 2, or LOW. Transmission Range represents the decoded status of the four 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: 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 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.
TRANS. HOT MODE: Scan Tool Displays ACTIVE or INACTIVE.
ACTIVE displayed indicates that the PCM has detected conditions appropriate for Transaxle hot mode operation. The PCM determines this base on Transaxle fluid temperature. While in Hot Mode, Transaxle shift points may be altered, 4th gear disabled, and the TCC forced ON in 2nd gear.
TWC DIAGNOSTIC: Scan Tool Displays ENABLED or DISABLED.
ENABLED displayed indicates that MAF, HO2S, ECT, or VSS DTCs that would disable the TWO diagnostic are not present.
TWC MONITOR TEST COUNTER: Scan Tool Range 0-49. The TWC monitor test counter increments while the TWO system diagnostic test is running and taking samples. When the TWO Monitor Test Counter reaches 49, the PCM will update the TWC diagnostic statistical filter. At this point, the TWO Monitor Test Counter will reset to 0 and begin incrementing again. The TWO Monitor Test Counter is most useful when verifying a Three-way catalytic converter replacement or any repair associated with the DTC P0420 diagnostic table.
TWC PROTECTION: Scan Tool Displays ACTIVE or INACTIVE.
ACTIVE displayed indicates that the PCM has detected conditions appropriate to operate in TWO Protection mode. This is determined based on Engine Load and Engine Coolant Temperature. While in TWO Protection, the PCM will decrease Air/Fuel Ratio to a value that depends on Mass Air Flow (higher Mass Airflow = lower Air/Fuel Ratio).
VEHICLE SPEED: Scan Tool Range 0-255 km/h, 0-155 mph.
The vehicle speed sensor signal is converted into mph and km/h for display.