Part 2

Scan Tool Data Definitions - Continued

HO2S 1
- Scan tool range 0-1,132 mV. Represents the fuel control exhaust oxygen sensor (O2S) output voltage. Should fluctuate constantly within a range between 10 mV, lean exhaust, and 1,000 mV, rich exhaust, while operating in Closed Loop.

HO2S 2
- Scan tool range 0-1,132 mV. Represents the catalyst monitor exhaust O2S output voltage. If the catalyst is operating efficiently, the heated oxygen sensor (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 1 and 2 Heater Circuit Status
- The HO2S Heater Circuit Status indicates the diagnostic state of the output driver for the heater control circuit. The scan tool displays Fault, OK, or Invalid State.

HO2S 1 and 2 Heater Command
- The HO2S 1 and 2 Heater Command displays the commanded state of the HO2S heater. The scan tool displays ON or OFF.

HO2S 1 and 2 Heater Current
- The HO2S 1 and 2 Heater Current displays the current through the control module when the HO2S Heater is commanded ON. The scan tool displays the current in amperage.

IAT Sensor
- Scan tool range -40 to +151°C (-40 to +304°F). The PCM converts the resistance of the intake air temperature (IAT) sensor to degrees. The PCM uses 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 Signal
- Scan tool range 0-25.5 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 (ICM) is controlling the spark advance at a fixed 10 degrees before top dead center (BTDC), bypass mode. IC displayed indicates that the PCM has requested control of the spark advance, IC mode. The ICM determines the correct operating mode based on the level of voltage that the PCM applies to the ICM bypass circuit. The PCM provides 5 volts to the ICM 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 ICM does not receive the voltage, the module will control spark timing.

IMS
- The Internal Mode Switch (IMS) displays active position of the transmission shift position. The scan tool displays P, R, N, D4, D3, D2, D1.

Initial Brake Apply Signal
- The Initial Brake Apply Signal displays the active position of the brake switch. The scan tool displays Applied/Released.

Injector PWM
- Injector PWM indicates the commanded PWM of the fuel injectors. The scan tool displays milliseconds.

Knock Retard
- Scan tool range 0.0-25.5 degrees. Indicates the amount of spark the PCM is removing from the IC spark advance in response to the signal from the knock sensors (KS). The traction control system Desired Torque signal from the electronic brake and traction control (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 to +16 percent. Long term FT is derived from the short term FT 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 FT, 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 FT allows a range between -23 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 O2S voltage. In Open Loop, the PCM ignores the O2S voltage and bases the amount of fuel to be delivered on TP, ECT, and MAF sensor inputs only.

MAF Sensor
- Scan tool range 0.0-512 gm/s. 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
- Scan tool range 0-32,000 Hz. The MAF sensor input signal to the PCM is a frequency which varies from around 3,000 Hz at idle to above 7,000 Hz at WOT. The PCM converts this frequency signal to grams per second to be displayed on the scan tool as MAF.

MAP Sensor
- Scan tool range 10-105 kPa/0.00- 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 Command
- Scan tool displays ON or OFF. Indicates the PCM commanded state of the malfunction indicator lamp (MIL).

MIL Circuit Status
- MIL Circuit Status indicates the diagnostic state of the output driver for the MIL circuit. The scan tool displays Fault, OK or Invalid State.

Misfire Current Cyl. 1-6
- Scan tool range 0-198 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. 1-6
- Scan tool range 0-65535 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.

Number of DTC(s)
- Scan Tool Displays- number

This parameter displays the quantity of active DTCs.

PCM/VCM in VTD Fail Enable
- Scan Tool Displays-ACTIVE or INACTIVE.

If applicable. The theft deterrent fuel enable is an input from the vehicle theft deterrent (VTD) system that signals the PCM to enable the injectors and the crank relay if the proper signal is received. The scan tool will normally display INACTIVE. If the VTD system does not send the correct theft deterrent fuel enable signal to the PCM, the display will switch to ACTIVE and the fuel system and starter control may be disabled. Refer to VTD diagnosis for further information.

Power Enrichment
- Scan tool displays ACTIVE or INACTIVE. ACTIVE displayed indicates that the PCM has detected conditions appropriate to operate in power enrichment (PE) mode. The PCM will command PE mode when a large increase in TP and load is detected. While in PE, 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.

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

Short Term FT
- Scan tool range -11 to +20 percent. Short term FT represents a short-term correction to fuel delivery by the PCM in response to the amount of time the fuel control O2S voltage spends above or below the 450 mV threshold. If the O2S voltage has mainly remained less than 450 mV, indicating a lean air/fuel mixture, short term FT will increase into the positive range above 0 percent and the PCM will add fuel. If the O2S 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 FT to read in the negative range during normal operation. The PCMs maximum authority to control fuel trim allows a range between -11 to +20 percent. Fuel trim values at maximum authority may indicate an excessively rich or lean system.

Spark
- Scan tool range -64 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 ICM sets spark advance at a fixed value of 10 degrees BTDC while operating in bypass mode, the displayed Spark advance only reflects true spark timing when the PCM has commanded IC mode.

Starter Enable Relay Circuit Status
- Starter Enable Relay Circuit Status indicates the diagnostic state of the output driver for the starter enable relay control circuit. The scan tool displays Fault, OK or Invalid State.

Starter Relay Command
- Scan tool displays ON or OFF. A Disabled display indicates that the PCM has inhibited starter relay operation. The PCM will inhibit starter relay operation if the engine is running, a correct VTD password has not been received from the VTD module or if the starter is engaged for an extended period of time.

Start-Up ECT
- Scan tool range -40 to +151°C (40 to +304°F). Indicates the ECT 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 to +151°C (-40 to +304°F). Indicates the IAT at the time that the vehicle was started. Used by the HO2S diagnostic to determine if the last startup was a cold start.

Stop Lamp Signal
- The Stop Lamp Signal displays the active position of the Stop Lamp Switch. The scan tool displays ON or OFF.

TAC/PCM Communication Signal
- This parameter indicates the status of the communication between the TAC module and the control module. The scan tool will display OK if the circuits are operating normally. The scan tool will display Fault if there is an interruption in the communication.

TCC Brake Pedal Switch
- Torque control converter (TCC) brake pedal switch indicates the state of the switch. The scan tool displays Applied or Released.

TCC PWM Solenoid Circuit
- The TCC PWM Solenoid Circuit indicates the diagnostic state of the output driver for the TCC PWM solenoid control circuit.

TCC PWM Solenoid Command
- TCC PWM Solenoid Command indicates the commanded PWM signal to the solenoid. The scan tool displays Hz.

TCS Circuit Status
- Traction control system (TCS) Circuit Status indicates the diagnostic state of the output driver for the TCS circuit. The scan tool displays Fault, OK or Invalid State.

TP Desired Angle
- This parameter indicates the TP angle commanded by the control module. The scan tool will display a low value at idle, and a high value at wide open throttle (WOT).

TP Indicated Angle
- This parameter displays the angel 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 plates are closed. The scan tool will display a high percentage when the throttle plates are 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 plates. This parameter is for sensor 1 of the throttle position (TP) sensor assembly. The scan tool will display a low voltage when the throttle plates are at rest. The scan tool will display a high voltage when the throttle plates are 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 plates are closed. The scan tool will display a high percentage when the throttle plates are fully open.

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 plates. This parameter is for sensor 2 of the throttle position (TP) sensor assembly. The scan tool will display a high voltage when the throttle plates are at rest. The scan tool will display a low voltage when the throttle plates are 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 plates are closed. The scan tool will display a high percentage when the throttle plates are fully open.

TP Sensor
- Scan tool range 0.00-5.00 Volts. The voltage being monitored by the PCM on the TP sensor signal circuit.

Traction Control Status (If Equipped)
- Scan tool displays ACTIVE or INACTIVE. ACTIVE displayed indicates that the traction control system is taking action to reduce drive wheel slippage.

Torque Request Signal (If Equipped)
- Scan tool range 0-100 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 solenoid PWM, or increasing air/fuel ratio. The PCM can also turn OFF up to 3 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.

Torque Delivered Signal (If Equipped)
- Scan tool range 0-100 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.

Vehicle Speed Sensor
- Scan tool range 0-255 km/h, 0-155 mph. The vehicle speed sensor (VSS) signal is converted into km/h and mph for display.

VTD Auto. Learn Timer
- Scan Tool Displays-ACTIVE or INACTIVE.

The auto learn timer is the indication if the VTD system is in the learn mode and has not timed out.

VTD Fuel Disable
- Scan Tool Displays-ACTIVE or INACTIVE.

If applicable. The theft deterrent fuel enable is an input from the VTD system that signals the PCM to enable the injectors and the crank relay if the proper signal is received. The scan tool will normally display INACTIVE. If the VTD system does not send the correct theft deterrent fuel enable signal to the PCM, the display will switch to ACTIVE and the fuel system and starter control may be disabled. Refer to VTD diagnosis for further information.

VTD Fuel Disable Until Ign. OFF
- Scan Tool Displays-Yes or NO

With the ignition ON and a VTD code present, the scan tool displays Yes.