Part 2 - G to Z

SCAN TOOL DATA DEFINITIONS

Generator Lamp: Scan tool displays ON or OFF. Represents the commanded state of the generator lamp control circuit.

Generator PWM: Scan tool range 0 percent to 100 percent. 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 spark and IAC to compensate for variances in engine load caused by the generator.

HO2S Sensor 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 Sensor 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 Sensor 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 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. An 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: Scan tool 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. The PCM uses Intake Air Temperature (IAT) to adjust fuel delivery and spark timing according to incoming air density. IAT is also compared to ECT at startup to identify cold starts for the HO2S heater and the EVAP diagnostics.

Ignition 1: Scan tool range 0 to 25.5 Volts. 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 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 it, the module will control spark timing.

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 degrees to 25.5 degrees. 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 more than 0.0 degrees if Traction Control is active.

Long Term FT: Scan tool range -23 percent to 16 percent. 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 percent indicates that fuel delivery requires no compensation to maintain the PCM commanded air/fuel ratio. A negative value significantly below 0 percent indicates that the fuel system is rich and fuel delivery is being reduced (decreased injector pulse width). A positive value significantly more than 0 percent 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 percent and +16 percent. Fuel trim values at or near 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. Represents the commanded state of the Low Oil Lamp indicator control circuit.

MAF: Scan tool range 0.0-512 g/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 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 on the scan tool as MAF.

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 many of the diagnostics.

MIL: Scan tool displays ON or OFF. Indicates the PCM commanded state of the Malfunction Indicator Lamp.

Misfire Current Cyl #1 / Misfire Current Cyl #2 / Misfire Current Cyl #3 / Misfire Current Cyl #4 / Misfire Current Cyl #5 / Misfire Current Cyl #6: Scan tool range 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: Scan tool range 0 to 65,535 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).

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 Status: Scan tool displays RICH or LEAN. Indicates whether oxygen sensor voltage is more 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 FT: Scan tool range -11 percent to 20 percent. 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 percent and the PCM will add fuel. If the oxygen sensor voltage stays mainly above the threshold, short term fuel trim will decrease below 0 percent 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 percent and +20 percent. Fuel trim values at maximum authority may indicate an excessively rich or lean system.

Spark: Scan tool range -64 degrees to 64 degrees. 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.

TCC Solenoid: Scan tool indicates Fault or OK. Represents the diagnostic state of the driver module for the TCC Solenoid control circuit.

Throttle At Idle: Scan tool displays YES or NO. Indicates whether the TP Angle being monitored by the PCM is at 0 percent.

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 percent to 100 percent. TP Angle is computed by the PCM from the TP Sensor voltage. TP Angle should display 0 percent at idle and 100 percent 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 percent to 100 percent. 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 percent to 100 percent. 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.

TWC Protection: Scan tool displays ACTIVE or INACTIVE. ACTIVE displayed indicates that the PCM has detected conditions appropriate to operate in TWC Protection mode. This is determined based on Engine Load and Engine Coolant Temperature. While in TWC 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.

VTD Fuel Disable: Scan tool displays Active of Inactive. Represents whether VTD is disabling fuel.

1 - 2 Solenoid: Scan tool indicates Fault or OK. Represents the diagnostic state of the driver module for the 1 - 2 Solenoid control circuit.

2 - 3 Solenoid: Scan tool indicates Fault or OK. Represents the diagnostic state of the driver module for the 2 - 3 Solenoid control circuit.

3X Crank Sensor: Scan tool displays RPM. Represents engine speed as calculated from the 3X reference signal.

18X Crank Sensor: Scan tool displays RPM. Represents engine speed as calculated from the 18X reference signal.