Part 2

Scan Tool Data Definitions

HO2S 1 Heater
- This parameter displays the current through the control module when the HO2S 1 heater is commanded ON by the control module. HO2S 1 Heater Current is a range of values indicating a low current when the heater circuit resistance is high to a high current when the heater circuit resistance is low.

HO2S 2 Heater
- This parameter displays the current through the control module when the HO2S 2 heater is commanded ON by the control module. HO2S 2 Heater Current is a range of values indicating a low current when the heater circuit resistance is high to a high current when the heater circuit resistance is low.

IAT Sensor
- The powertrain control module (PCM) converts the resistance of the intake air temperature (IAT) sensor to degrees. The PCM uses the IAT in order to adjust fuel delivery and spark timing according to incoming air density.

Initial Brake Apply Signal
- This parameter displays the state of the brake pedal that is transmitted over the serial data circuit from the electronic brake control module (EBCM).

Ignition 1 Signal
- This parameter displays the voltage measured at the ignition 1 circuit of the control module. Voltage is applied to the control module when the ignition switch is in the ignition 1 position.

Injector PWM
- Indicates the base pulse width modulation (PWM) or ON time of the fuel injectors in milliseconds. When the engine load is increased, the injector pulse width will increase.

Knock Retard
- Knock retard indicates the amount of spark the powertrain control module (PCM) removes from the spark advance in response to the signal from the knock sensors.

Long Term FT
- The scan tool displays percentage. The powertrain control module (PCM) derives the long term fuel trim from the short term fuel trim value. The long term fuel trim represents a long term correction of fuel delivery. A value of 0 percent indicates that fuel delivery requires no compensation in order to maintain the PCM commanded air/fuel ratio. A negative value significantly below 0 percent indicates that the fuel system is rich and the PCM is reducing the fuel delivery. A positive value significantly more than 0 percent indicates that a lean condition exists and the PCM compensates by adding fuel. Fuel trim values at maximum authority indicates an excessively rich or lean system.

Long Term FT Avg.
- This parameter is the average long term fuel trim for this bank as calculated by the control module. The scan tool will display a value more than 0 percent indicating that time is being added to the injector pulse width, increasing the amount of fuel to this bank of the engine. The scan tool will display a value of less than 0, indicating time is being subtracted from the injector pulse width, reducing the amount of fuel to this bank of the engine. A value of 0 percent indicates no compensation is required to operate the engine at the desired air/fuel ratio.

Loop Status
- The scan tool displays Open or Closed. Closed Loop indicates that the powertrain control module (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 throttle position (TP) sensor, engine coolant temperature (ECT) sensor inputs only.

MAF Sensor
- Mass air flow (MAF) is the MAF input frequency converted to grams of air per second. This indicates the amount of air entering the engine.

MAF Sensor
- The mass air flow sensor input signal to the PCM is a frequency which varies from around 3,000 Hz at idle to above 7,000 Hz at wide open throttle (WOT). The PCM converts this frequency signal to grams per second to be displayed on the scan tool as MAF.

MAP Sensor
- The manifold absolute pressure (MAP) sensor measures the absolute pressure in the intake manifold.

Medium Resolution Resync Counter
- The medium resolution resync counter displays the number of times the PCM had to resync the crankshaft position (CKP) sensor.

MIL Command
- This parameter displays the commanded state of the malfunction indicator lamp (MIL) control circuit. The malfunction indicator lamp should be on when the scan tool indicates the MIL Command is On. The malfunction indicator lamp should be off when the scan tool indicates the MIL Command is Off. The control module will command the MIL On when the ignition is ON with the engine OFF in order to perform a bulb check.

Mileage Since DTC Cleared
- This parameter displays the mileage that has elapsed since any diagnostic trouble code (DTC) has been cleared from the control modules memory.

Misfire Current Cyl. #1 - #4
- The misfire current counters increment at a rate according to the number of possible misfires the powertrain control module (PCM) detects on each cylinder during the last 200 cylinder firing events. The counters may normally display some activity, but the activity should be nearly equal for all the cylinders.

Misfire History Cyl. #1 - #4
- The misfire history counters display the total level of misfire that has been detected on each cylinder. The misfire history counters will not update or show any activity until a misfire DTC P0300 has become active. The misfire history counters will update every 200 cylinder firing events.

PCM Reset
- The scan tool displays Yes or No. This parameter indicates when the internal PCM resets. The scan tool displays YES when an internal PCM reset occurred. The scan tool displays NO under the normal operating conditions.

Power Enrichment
- The scan tool displays Active/Inactive. The scan tool indicates when power enrichment mode is active (moderate to heavy acceleration). Helpful in diagnosing DTC P1171.

Reduced Engine Power
- The scan tool displays Active or Inactive. The scan tool displays Active when the PCM receives a signal from the TAC module that a throttle actuator control system fault is occurring. The PCM limits the engine power.

Short Term FT
- The scan tool displays percentage. The short term fuel trim represents a short term correction to fuel delivery by the powertrain control module (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 mainly remains less than 450 mV, indicating a lean air/fuel mixture, short term fuel trim increases into the positive range above 0 percent. The PCM adds fuel. If the oxygen sensor voltage stays mainly above the threshold, the short term fuel trim decreases below 0 percent into the negative range. The PCM reduces the fuel delivery in order to compensate for the indicated rich condition. Under certain conditions such as an extended idle and a high ambient temperature, the canister purge may cause the short term fuel trim to read in the negative range during normal operation. The fuel trim values at maximum authority may indicate an excessively rich or lean system.

Short Term FT Avg.
- The scan tool displays %. This parameter indicates the average short term fuel trim for this bank. The scan tool will display a value more than 0 if the time is being added to the injector pulse width, increasing the amount of fuel to that bank of the engine to compensate for a lean condition sensed by the oxygen sensors on that bank. The scan tool will display a value less than 0 if time is being subtracted from the injector pulse width, reducing the amount of fuel to the engine to compensate for a rich condition sensed by the oxygen sensors on that bank. A value of 0 percent indicates no compensation is required to operate the engine at the desired air/fuel ratio.

Spark
- The scan tool displays the amount of degrees the powertrain control module (PCM) commands the spark advance. The PCM computes the desired spark advance using the following:

1. Engine coolant temperature (ECT)
2. Engine speed (RPM),
3. Load
4. Vehicle speed

The PCM adjusts the timing.

Start Up ECT
- The scan tool displays the engine coolant temperature (ECT) at the time the engine was started. The powertrain control module (PCM) uses start-up ECT for certain diagnostic trouble codes (DTCs).

Start Up IAT
- Indicated the intake air temperature (IAT) at the time that the vehicle was started. Used to determine if the last start-up was a cold start. This parameter indicates the ambient air temperature at start-up.

Starter Relay Command
- This parameter displays the status of the output driver for the starter relay control circuit. The scan tool will display ON/OFF.

Stoplamp Pedal Switch
- This parameter displays the position of the stoplamp pedal switch input to the control module.

Torque Delivered Signal
- 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.

Torque Request Signal
- Represents the PWM signal from the electronic brake and traction control module (EBTCM). 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.

Total Misfire Count
- This parameter indicates the total level of misfire that has been detected on each cylinder. The misfire history counters will not update or show any activity until a misfire or DTC P0300 has become active. The misfire history counter will update every 200 cylinder firing events.

TP 1 Learned Min
- This parameter displays the learned minimum value of TP sensor 1 as recorded by the control module on start-up for the ignition cycle.

TP 2 Learned Min
- This parameter displays the learned minimum value of TP sensor 2 as recorded by the control module on start-up for the ignition cycle.

TP Desired Angle
- The powertrain control module (PCM) indicates the desired throttle angle commanded by the vehicle operator.

TP Indicated Angle
- This parameter displays the angle of the throttle position (TP) in percent. This information is calculated by the control module using the signals from the throttle position sensors. The scan tool will display a low percentage when the throttle plate is closed. The scan tool will display a high percentage when the throttle plate is fully open.

TP Sensor 1
- This parameter displays the voltage signal sent to the control module from the sensor used to monitor the position of the throttle plate. This parameter is for sensor 1 of the throttle position (TP) sensor assembly. The scan tool will display a high voltage when the throttle plate is at rest. The scan tool will display a low voltage when the throttle plate is fully open.

TP Sensor 1
- This parameter displays the angle of the throttle position (TP) sensor 1 in percent. This information is calculated by the control module using the signal from the throttle position sensor 1. The scan tool will display a low percentage when the throttle plate is closed. The scan tool will display a high percentage when the throttle plate is fully open.

TP Sensors 1 and 2
- This parameter displays the results of a control module test that compares the signals from the throttle position (TP) sensors 1 and 2. The scan tool will display Agree when the signal from TP sensor 1 corresponds with the signal from TP sensor 2. The scan tool will display Disagree when the signal from TP sensor 1 conflicts with the signal from TP sensor 2.

TP Sensor 2
- This parameter displays the voltage signal sent to the control module from the sensor used to monitor the position of the throttle plate. This parameter is for sensor 2 of the throttle position (TP) sensor assembly. The scan tool will display a low voltage when the throttle plate is at rest. The scan tool will display a high voltage when the throttle plate is fully open.

TP Sensor 2
- This parameter displays the angle of the throttle position (TP) sensor 2 in percent. This information is calculated by the control module using the signal from the throttle position sensor 2. The scan tool will display a low percentage when the throttle plate is closed. The scan tool will display a high percentage when the throttle plate is fully open.

Traction Control Status
- This parameter displays the status of the traction control circuit. The scan tool displays active if the PCM receives a signal from the electronic brake and traction control module (EBTCM) requesting torque reduction during a traction control event.

TWC Temperature Calculated
- Represents the calculated temperature of the catalytic converter. Useful for determining if the Catalyst Monitor Test has run.

Vehicle Security Status
- This parameter displays the status of the vehicle theft deterrent system. The scan tool will display fuel enabled or fuel disabled.

Vehicle Speed Sensor
- The scan tool displays km/h and mph. The vehicle speed sensor signal is converted into km/h and mph for display on the scan tool.

Warm-ups w/o Emission Faults
- This parameter counts the number of warm-up cycles without an emission fault present. The counter increments to 255 and rolls back to 0 unless a fault occurs. If a fault occurs, the counter reverts back to 0 until the fault is corrected. Clearing the information with a scan tool or a loss of power to the PCM also resets the counter to 0. The scan tool displays counts. This display indicates the number of warm-up cycles without a emission failure.

Warm-ups w/o Non-Emission Faults
- This parameter counts the number of warm-up cycles without a non-emission fault present. The counter increments to 255 and rolls back to 0 unless a fault occurs. If a fault occurs, the counter reverts back to 0 until the fault is corrected. Clearing the information with a scan tool or a loss of power to the PCM also resets the counter to 0.