GM Service Manual Online
For 1990-2009 cars only

The Engine Scan Tool Data Definitions contains a brief description of all engine related parameters available on the scan tool. The list is arranged in alphabetical order. A given parameter may appear in any one of the data lists. In some cases, the parameter may appear more than once or in more than one data list in order to group certain related parameters together.

5-Volt Reference 1: This parameter displays the voltage sensed on the 5-volt reference 1 circuit at the control module. The scan tool will display a higher value at higher voltage. The scan tool will display a lower value at lower voltage.

5-Volt Reference 1 Circuit Status: This parameter will display OK if the circuit is good or Fault if a short to ground, short to B+, or open circuit is present.

5-Volt Reference 2: This parameter displays the voltage sensed on the 5-volt reference 2 circuit at the control module. The scan tool will display a higher value at higher voltage. The scan tool will display a lower value at lower voltage.

5-Volt Reference 2 Circuit Status: This parameter will display OK if the circuit is good or Fault if a short to ground, short to B+, or open circuit is present.

A/C Relay Command: This parameter displays the commanded state of the A/C clutch relay control circuit. The scan tool will display ON or OFF. ON indicates the A/C clutch relay control circuit is being grounded by the control module, allowing voltage to the A/C compressor clutch. OFF indicates the A/C clutch relay is not being commanded on by the control module.

Air Flow Calculated: This parameter displays the air flow of the engine as calculated by the control module using information from the manifold absolute pressure (MAP) sensor. The scan tool will display a range of values indicating a high air flow when MAP pressure is high and a low air flow when MAP pressure is low. This value is listed in grams per second (g/s).

Ambient Air Temperature: Outside temperature at any given altitude expressed in degrees.

APP Indicated Angle: This parameter displays the angle of the accelerator pedal as calculated by the control module using the signals from the accelerator pedal position (APP) sensors. The accelerator pedal position indicated angle is a range of values indicating a low percentage when the accelerator pedal is not depressed to a high percentage when the accelerator pedal is fully depressed.

APP Sensor 1: This parameter displays the voltage signal sent to the control module from APP sensor 1 of the APP sensor assembly. APP sensor 1 is a range of values indicating a low voltage when the accelerator pedal is not depressed to a high voltage when the accelerator pedal is fully depressed.

APP Sensor 1 Indicated Position: This parameter displays the angle of the APP sensor 1 as calculated by the control module using the signal from the APP sensor 1. APP sensor 1 is a range of values indicating a low percentage when the accelerator pedal is not depressed to a high percentage when the accelerator pedal is fully depressed.

APP Sensor 1 and 2: This parameter displays the results of a control module test that compares the signals from the APP sensors 1 and 2 . The scan tool will display Agree or Disagree. Agree indicates that APP sensor 1 and APP sensor 2 voltages correspond to the same accelerator pedal position. Disagree indicates that APP sensor 1 and APP sensor 2 voltages correspond to different accelerator pedal positions.

APP Sensor 2: This parameter displays the voltage signal sent to the control module from APP sensor 2 of the APP sensor assembly. APP sensor 2 is a range of values indicating a low voltage when the accelerator pedal is not depressed to a high voltage when the accelerator pedal is fully depressed.

APP Sensor 2 Indicated Position: This parameter displays the angle of the APP sensor 2 as calculated by the control module using the signal from the APP sensor 2. APP sensor 2 is a range of values indicating a low percentage when the accelerator pedal is not depressed to a high percentage when the accelerator pedal is fully depressed.

BARO: This parameter displays the barometric pressure as calculated by the control module using the signal from the MAP sensor measured when the ignition is turned on with the engine not running. The control module will update the barometric pressure during wide-open throttle (WOT) conditions.

BPP Signal: This parameter displays the state of the brake pedal position switch as determined by the brake pedal switch. The scan tool will display Applied when the brake pedal is depressed, and Released when the brake pedal is not depressed.

Calc. TWC Temp: Calculated catalytic converter temperature.

Catalytic Converter Protection Active: This parameter displays the state of the Catalytic Converter Protection mode.

CKP Active Counter: This parameter displays an incrementing counter when the control module receives a signal from the crankshaft position sensor (CKP).

CKP Resync Counter: This parameter displays the number of times the control module has to resynchronize the CKP sensor.

CKP Sensor:  This parameter displays the RPM that the control module is using for crankshaft position sensing.

CMP Sensor: This parameter displays the speed of the engine as calculated by the signal from the camshaft position (CMP) sensor, shown in RPM.

Cold Startup: This parameter displays whether the engine meets the conditions for a cold startup during the present ignition cycle. The scan tool displays Yes when the conditions for a cold startup are met during this ignition cycle. The scan tool displays No when the conditions for a cold startup are not met during the present ignition cycle. Conditions for a cold startup require the coolant temperature and the intake air temperature to be below a predetermined temperature and within a certain range of each other. These conditions must occur after the engine was warmed up to a specific temperature during the previous ignition cycle.

Cruise Control Active: This parameter displays the status of the cruise control system as determined by the control module. The scan tool will display Yes when the cruise control system is in control of vehicle speed. The scan tool will display No when the cruise control system is not operating.

Cycles Of Misfire Data: This parameter displays the number of cylinder firing events that were recorded as misfires as determined by the control module.

Cylinder 1 IC Circuit Status: This parameter displays the current diagnostic state of the output driver for the injector control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground, or a short to voltage on the circuit.

Cylinder 2 IC Circuit Status: This parameter displays the current diagnostic state of the output driver for the injector control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground, or a short to voltage on the circuit.

Cylinder 3 IC Circuit Status: This parameter displays the current diagnostic state of the output driver for the injector control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground, or a short to voltage on the circuit.

Cylinder 4 IC Circuit Status: This parameter displays the current diagnostic state of the output driver for the injector control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground, or a short to voltage on the circuit.

Cylinder 1 Injector Circuit Status: This parameter displays the current diagnostic state of the output driver for the injector control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground, or a short to voltage on the circuit.

Cylinder 2 Injector Circuit Status: This parameter displays the current diagnostic state of the output driver for the injector control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground, or a short to voltage on the circuit.

Cylinder 3 Injector Circuit Status: This parameter displays the current diagnostic state of the output driver for the injector control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground, or a short to voltage on the circuit.

Cylinder 4 Injector Circuit Status: This parameter displays the current diagnostic state of the output driver for the injector control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground, or a short to voltage on the circuit.

Decel. Fuel Cutoff: This parameter displays the status of the operating mode used to turn off the fuel injectors during certain deceleration conditions. When the scan tool displays Active, the control module has turned off the fuel injectors. When the scan tool displays Inactive, the fuel system is operating normally.

Desired Exh. CMP: This parameter displays the desired exhaust camshaft position, as determined by the control module. The scan tool will display a higher value for more advanced exhaust valve timing, such as at high load or speed conditions. The scan tool will display a lower value for a less advanced exhaust valve timing, such as at idle.

Desired Idle Speed: This parameter displays the engine idle speed in RPM commanded by the control module. The control module compensates for various engine loads in order to maintain the desired engine RPM at idle. This parameter is not valid unless the engine is running.

Desired Int. CMP: This parameter displays the desired exhaust camshaft position, as determined by the control module. The scan tool will display a higher value for more advanced intake valve timing, such as at high load or speed conditions. The scan tool will display a lower value for a less advanced intake valve timing, such as at idle.

EC Ignition Relay Circuit Status: This parameter displays the status of the output driver for the EC ignition relay control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground or a short to voltage on the circuit.

EC Ignition Relay Command: This parameter displays the commanded state of the EC ignition relay control circuit. The scan tool will display ON or OFF. ON indicates the EC ignition relay control circuit is being grounded by the control module, allowing voltage to the ignition system. OFF indicates the EC ignition relay is not being commanded on by the control module.

EC Ignition Relay Feedback Signal: This parameter displays the voltage signal sent to the control module from the engine control ignition relay. The scan tool will display battery voltage when the engine is running. The scan tool will display no voltage when the relay is OFF.

ECT Sensor: This parameter displays the temperature of the engine coolant based on the input from the engine coolant temperature (ECT) sensor. When the coolant temperature is low, the scan tool will display a low temperature. When the coolant temperature is high, the scan tool will display a high temperature.

Engine Load: This parameter displays the engine load in percent based on inputs to the control module from various engine sensors. The scan tool will display a low percentage when the engine is at idle with little or no load. The scan tool will display a high percentage when the engine is running at a high RPM under a heavy load.

Engine Off Time: This parameter displays the time elapsed since the engine was shut off.

Engine Oil Life Remaining: This parameter displays the amount engine oil life remaining before requiring an oil change based on calculations by the control module. The scan tool will display lower values as the engine oil life approaches 0 miles.

Engine Oil Pressure Switch: This parameter displays the state of the engine oil pressure as determined by the control module. The control module monitors the engine oil pressure switch to determine if the engine oil pressure is sufficient. The scan tool will display low when the engine oil pressure is below a predetermined value. The scan tool displays OK or Low. This parameter displays whether or not sufficient engine oil pressure is present.

Engine Oil Temperature Calculated: This parameter displays the temperature of the engine oil as calculated by the control module using a signal from the engine oil temperature sensor. The engine oil temperature sensor has a range of values indicating a low value when the oil temperature is low to a high value when the oil temperature is high.

Engine Run Time: This parameter displays the time elapsed since the engine was started. The scan tool will display the time in hours, minutes and seconds. The engine run time will reset to zero when the engine stops running.

Engine Speed: This parameter displays the speed of the crankshaft as determined by the control module using an input from the CKP sensor. The scan tool will display a high value at high engine speeds and a low value at low engine speeds.

EVAP Fault History: This parameter displays the result of the evaporative emission (EVAP) system diagnostic. Scan tool displays NO FAULT, EXCESS VACUUM, PURGE VALVE LEAK, SMALL LEAK, or WEAK VACUUM. The EVAP Fault History indicates the status of EVAP system diagnostics performed by the ECM.

EVAP Purge Solenoid Circuit Status: This parameter displays the status of the output driver for the evaporative emission purge solenoid control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground or a short to voltage on the circuit.

EVAP Purge Solenoid Command: This parameter displays the on-time or duty cycle of the EVAP purge solenoid commanded by the control module expressed as a percent. The scan tool will display a high percentage when the control module is commanding the EVAP purge solenoid to be open a large amount . The scan tool will display a low percentage when the control module is commanding the EVAP purge solenoid to be open a small amount. The scan tool will display 0 when the control module is commanding the EVAP purge solenoid closed.

EVAP Vent Solenoid Circuit Status: This parameter displays the status of the output driver for the evaporative emission vent solenoid control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground or a short to voltage on the circuit.

EVAP Vent Solenoid Command: This parameter displays the state of the EVAP vent solenoid commanded by the control module expressed as a Venting or Not Venting. The scan tool will display a venting when the control module is commanding the EVAP vent solenoid to be open . The scan tool will display a not venting when the control module is commanding the EVAP vent solenoid to be closed.

Exh. CMP Active Counter: This parameter displays an incrementing counter when the control module receives a signal from the camshaft position (CMP) sensor.

Exh. CMP Angle: This parameter displays the degrees of advanced exhaust camshaft angle related to crankshaft position as determined by the control module based on input from the exhaust CMP sensors. The scan tool will display a higher value for a more advanced exhaust camshaft position. The scan tool will display a lower value when the exhaust camshaft is not being advanced, such as at idle.

Exh. CMP Command: This parameter displays the exhaust camshaft position in percent of range as commanded by the control module.

Exh. CMP Solenoid Circuit Status: This parameter displays the state of the exhaust camshaft actuator solenoid control circuit. The parameter displays Fault if the camshaft actuator solenoid control circuit is open, shorted to ground, or shorted to voltage. The parameter displays Indeterminate until the circuit has been commanded ON.

Exh. CMP Variance: This parameter displays in degrees, the difference between the desired exhaust camshaft position and he actual exhaust camshaft position.

Fuel Level Sensor: This parameter displays the approximate fuel level in the fuel tank as a voltage. The control module calculates this level using the signal from the sensor used to monitor the fuel level in the fuel tank. The scan tool will display a low reading when the fuel level in the tank is low or near empty. The scan tool will display a high reading when the fuel level in the tank is high or near full.

Fuel Pump Relay Circuit Status: This parameter displays the status of the output driver for the fuel pump relay control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground or a short to voltage on the circuit.

Fuel Pump Relay Command: This parameter displays the commanded state of the fuel pump relay control circuit. The fuel pump relay should be ON when the scan tool indicates the Fuel Pump Relay Command is On. The fuel pump relay should be OFF when the scan tool indicates the Fuel Pump Relay Command is Off.

Fuel Tank Level Remaining: This parameter displays the amount of fuel remaining in the fuel tank as a percentage. The control module calculates this level using the signal from the sensor used to monitor the fuel level in the fuel tank. The scan tool will display a low reading when the fuel level in the tank is low or near empty. The scan tool will display a high reading when the fuel level in the tank is high or near full.

Fuel Tank Pressure Sensor: This parameter displays the fuel tank pressure as calculated based on a signal sent to the control module from the fuel tank pressure (FTP) sensor. The scan tool will display a low value when the pressure in the fuel tank is low or a vacuum. The scan tool will display a high value when the pressure in the fuel tank is high.

Fuel Tank Rated Capacity: This parameter displays the rated maximum quantity of fuel the fuel tank will hold. This is calibrated in the control module to match the vehicle.

Fuel Trim Cell: This parameter displays the fuel trim cell number as calculated by the control module based on engine speed and load inputs. The scan tool will display a lower number as conditions are nearer to idle, and a higher value as conditions approach maximum engine speed and maximum load.

Fuel Trim Learn: This parameter indicates if the control module is adjusting long term fuel trim in response to the short term fuel trim. The scan tool displays Enabled or Disabled. When conditions are appropriate for enabling long term fuel trim corrections, the scan tool displays Enabled.

Fuel Trim System Test State: This parameter indicates the status of the Fuel Trim System Test. The scan tool will display Disabled, Enabled, Monitoring, or Run Purge Test.

Fuel Volatility:  This parameter indicates the rate the fuel can be vaporized in the cylinder as calculated by the control module. The scan tool will display HIGH when the fuel volatility is high. The scan tool will display LOW when the fuel volatility is low.

HO2S 1: The scan tool displays a range of 0-1,106 mV.

HO2S 1 Heater: This parameter displays the current through the control module when the heated oxygen sensor (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 1 Heater Circuit Status: This parameter displays the diagnostic state of the output driver for the heater control circuit of oxygen sensor 1. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground, or a short to voltage on the circuit.

HO2S 1 Heater Command: This parameter displays the commanded state of the heater control circuit for oxygen sensor 1. The oxygen sensor 1 heater should be on when the scan tool indicates the HO2S 1 Heater Command is On. The oxygen sensor 1 heater should be off when the scan tool indicates the HO2S 1 Heater Command is Off.

HO2S 2: The scan tool displays a range of 0-1,106 mV.

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.

HO2S 2 Heater Command: This parameter displays the commanded state of the heater control circuit for oxygen sensor 2. The oxygen sensor 1 heater should be on when the scan tool indicates the HO2S 2 Heater Command is ON. The oxygen sensor 2 heater should be OFF when the scan tool indicates the HO2S 2 Heater Command is OFF.

HO2S Sensor 2 Heater Circuit Status: This parameter displays the status of the output driver for the HO2S Heater Sen. 2. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground, or a short to voltage on the circuit.

Hot Open Loop: This parameter indicates the status of the fuel delivery system. The scan tool will display Active if the fuel system is running in open loop due to a temperature concern. The scan tool will display Inactive if the fuel system is operating normally.

IAT Sensor: The scan tool displays °C. The engine control module (ECM) converts the resistance of the intake air temperature (IAT) sensor to degrees in the same manner as the ECT sensor. Intake air temp is used by the ECM to adjust fuel delivery and spark timing according to incoming air density. The scan tool displays a range of -40 to +150°C (-40 to +302°F). The ECM converts the resistance of the intake air temperature sensor to degrees. The ECM uses the IAT in order to adjust fuel delivery and spark timing according to incoming air density.

Ignition Accessory Signal: This parameter displays the state of the ignition 0 input to the control module from the ignition switch. The scan tool will display ON when the ignition switch is in the ignition accessory position. The scan tool will display OFF when the ignition switch is in any other position.

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.

Inj. 1 Disabled Due to Misfire: This parameter displays the status of the fuel injector driver by the control module. The scan tool will display YES if the fuel injector is being disabled due to a misfire detection. The scan tool will display NO if the fuel injector is not being disabled by the control module due to a misfire.

Inj. 2 Disabled Due to Misfire: This parameter displays the status of the fuel injector driver by the control module. The scan tool will display YES if the fuel injector is being disabled due to a misfire detection. The scan tool will display NO if the fuel injector is not being disabled by the control module due to a misfire.

Inj. 3 Disabled Due to Misfire: This parameter displays the status of the fuel injector driver by the control module. The scan tool will display YES if the fuel injector is being disabled due to a misfire detection. The scan tool will display NO if the fuel injector is not being disabled by the control module due to a misfire.

Inj. 4 Disabled Due to Misfire: This parameter displays the status of the fuel injector driver by the control module. The scan tool will display YES if the fuel injector is being disabled due to a misfire detection. The scan tool will display NO if the fuel injector is not being disabled by the control module due to a misfire.

Injector PWM: The scan tool displays ms. 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. Indicates the amount of time the ECM 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.

Intake Manifold Pressure: This parameter displays the pressure difference between the MAP and the barometric pressure (BARO) as calculated by the control module. The scan tool will display a higher value during high vacuum conditions, such as idle or deceleration. The scan tool will display a lower value during low vacuum conditions, such as wide open throttle or high load cruising.

Int. CMP Active Counter: This parameter displays an incrementing counter when the control module receives a signal from the camshaft position (CMP) sensor.

Int. DMP Angle: This parameter displays the actual intake camshaft position in degrees.

Int. CMP Bank 1 Command: This parameter displays the intake camshaft position in percent of range as commanded by the control module.

Int. CMP Solenoid Circuit Status: This parameter displays the state of the intake camshaft actuator solenoid control circuit. The parameter displays Fault if the camshaft actuator solenoid control circuit is open, shorted to ground, or shorted to voltage. The parameter displays Indeterminate until the circuit has been commanded ON. This parameter may not change if the scan too is used to command the CMP solenoid ON.

Int. CMP Variance: This parameter displays in degrees, the difference between the desired intake camshaft position and the actual intake camshaft position.

Knock Retard: The scan tool displays °. Indicates the amount of spark the ECM is removing from ignition control (IC) spark advance in response to the signal from the knock sensors. The traction control system desired torque signal from the electronic brake and traction control module (EBTCM) may cause knock retard to display a value more than 0.0 degrees if traction control is active.

Knock Detected Cyl. 1: This parameter displays the status of each cylinder for knock detection by the control module. The scan tool will display YES if a knock condition has been detected related to that cylinder combustion event. The scan tool will display NO if there is no knock condition detected related to that cylinder combustion event.

Knock Detected Cyl. 2: This parameter displays the status of each cylinder for knock detection by the control module. The scan tool will display YES if a knock condition has been detected related to that cylinder combustion event. The scan tool will display NO if there is no knock condition detected related to that cylinder combustion event.

Knock Detected Cyl. 3: This parameter displays the status of each cylinder for knock detection by the control module. The scan tool will display YES if a knock condition has been detected related to that cylinder combustion event. The scan tool will display NO if there is no knock condition detected related to that cylinder combustion event.

Knock Detected Cyl. 4: This parameter displays the status of each cylinder for knock detection by the control module. The scan tool will display YES if a knock condition has been detected related to that cylinder combustion event. The scan tool will display NO if there is no knock condition detected related to that cylinder combustion event.

Long Term FT: The scan tool displays percentage. The ECM 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 ECM commanded air/fuel ratio. A negative value significantly below 0 percent indicates that the fuel system is rich and the ECM is reducing the fuel delivery. A positive value significantly more than 0  percent indicates that a lean condition exists and the ECM compensates by adding fuel. Fuel trim values at maximum authority indicates an excessively rich or lean system.

Long Term FT Test 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: Closed loop indicates that the ECM is controlling fuel delivery according to oxygen sensor voltage. In open loop, the ECM ignores the oxygen sensor voltage and bases the amount of fuel to be delivered on throttle position (TP) sensor, ECT, and mass air flow (MAF) sensor inputs only.

LT FT Test Avg. w/o Purge: This parameter is calculated by the control module based on the Short Term FT value. The Long Term FT is used for the long term correction of the fuel delivery in. The scan tool will display a high value for a large amount of long term fuel correction, and 0 percent for no long term fuel trim correction. The scan tool will display a negative value when fuel system is running too rich and fuel is being removed from the combustion event. The scan tool will display a positive value if the fuel system is running lean and fuel is being added to the combustion event.

MAF Sensor: The scan tool displays g/s The scan tool displays a range of 0.0-655 g/s. The 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 scan tool displays a range of 0-31,999 Hz. The MAF sensor is a hot wire type air flow sensor. The ECM converts current draw needed by the MAF to keep the hot wires at a constant into a frequency signal. The scan tool displays this frequency in a hertz signal.

MAF Performance Test: This parameter displays the status of the mass air flow (MAF) performance test by the control module. The scan tool will display OK if no fault is found. The scan tool will display Fault if the control module detects a fault during the test.

MAP Performance Test 1: This parameter displays the status of the MAP performance test 1 by the control module. The scan tool will display OK if no fault is found. The scan tool will display Fault if the control module detects a fault during the test.

MAP Performance Test 2: This parameter displays the status of the MAP performance test 2 by the control module. The scan tool will display OK if no fault is found. The scan tool will display Fault if the control module detects a fault during the test.

MAP Sensor: The scan tool displays kPa The MAP sensor measures the change in the intake manifold pressure which results from engine load and speed changes. As the intake manifold pressure increases, the air density in the intake also increases and additional fuel is required. The scan tool displays a range of 10-104 kPa. The MAP sensor measures the absolute pressure in the intake manifold.

MAP Sensor: The scan tool displays Volts The MAP sensor measures the change in the intake manifold pressure which results from engine load and speed changes. As the intake manifold pressure increases, the air density in the intake also increases and additional fuel is required. The scan tool displays a range of 0-5 volts. The MAP sensor measures the absolute pressure in the intake manifold.

MIL Circuit Status: This parameter displays the status of the output driver for the malfunction indicator lamp (MIL) control circuit. The scan tool will display OK if the circuit is operating correctly. The scan tool will display Fault if there is an open, short to ground or a short to voltage on the circuit.

MIL Command: This parameter displays the commanded state of the 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.

MIL Requested by DTC: This parameter indicates the reason the control module illuminated the MIL. The scan tool will display YES when the MIL is requested as a result of an A or B type DTC. The scan tool will display NO if the MIL is illuminated for another reason, such as transmission DTCs.

Misfire Current Cyl. 1-4: The scan tool displays 0-255 counts. The display shows the number of misfires that have been detected during the last 200 cylinder firing events. The counters may normally display some activity, but the activity should be nearly equal for all of the cylinders, and in low numbers.

Misfire History Cyl. 1-4: The scan tool range is 0-255 counts. 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.

PNP Switch: This parameter displays whether the transmission range selector is in Park or Neutral.

Power Enrichment: Scan tool displays ACTIVE or INACTIVE. ACTIVE displayed indicates that the ECM has detected conditions appropriate to operate in Power Enrichment mode. The ECM will command Power Enrichment mode when a large increase in throttle position and load is detected. While in Power Enrichment, the ECM 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 ECM receives a signal from the TAC module that a throttle actuator control system fault is occurring. The ECM 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 ECM 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 ECM 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 ECM 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 Test 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 a range of -64 to +64°. The scan tool displays the amount of degrees the ECM commands. The ECM computes the desired spark advance using the following: (1) ECT, (2) engine speed (RPM), (3) load, (4) vehicle speed. The ECM adjusts the timing. 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.

Start Up ECT: Indicates the engine coolant temperature at engine start up. The scan tool displays a range of -40 to +150°C (-40 to +302°F). The scan tool displays the engine ECT at the time the engine was started. The ECM uses start-up ECT for certain DTCs.

Start Up IAT: Indicates the IAT at the time that the vehicle was started. The scan tool range is -40 to +150°C (-40 to +302°F). This parameter indicates the ambient air temperature at start-up.

TCC/Cruise Brake Pedal Switch: This parameter displays the position of the torque converter clutch (TCC) brake pedal switch input to the control module. The scan tool displays Applied, Released, or Invalid.

TCS Torque Delivered Signal: Represents the pulse width modulation (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 ECM is responding properly to the traction control desired torque signal.

TCS Torque Signal: Represents the PWM signal from the EBTCM. The EBTCM reduces the traction control desired torque signal pulse width when a drive wheel slippage situation is detected. The ECM monitors the traction control desired torque signal and reduces drive wheel slippage as necessary by retarding spark timing.

Total Knock Retard: This parameter indicates how much ignition spark timing is being retarded due to all control systems monitored by the control module. The scan tool will display a high value during extreme conditions such as high temperatures and antilock braking. The scan tool will display a lower value during lighter driving conditions.

Total Misfire Count: The scan tool range is 0-255 counts. 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 Sensor 1 Learned Minimum: 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 Sensor 2 Learned Minimum: 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 scan tool displays %. The scan tool displays 0-100 percent. The ECM indicates the desired throttle angle commanded by the vehicle operator. The scan tool indicates the desired throttle angle commanded by the vehicle operator.

TP Indicated Angle: This parameter displays the angle of the 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 Performance Test: This parameter displays the status of the TP performance test by the control module. The scan tool will display OK if no fault is found. The scan tool will display Fault if the control module detects a fault during the test.

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 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 Sensors 1 and 2: This parameter displays the results of a control module test that compares the signals from the 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 1 Indicated Position: This parameter displays the angle of the 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 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 Indicated Position: This parameter displays the angle of the 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.

Vehicle Speed Sensor: This parameter indicates the vehicle speed as calculated by the control module based on a signal from the vehicle speed sensor (VSS). The scan tool will display a higher value at higher vehicle speeds, and a lower value at lower vehicle speeds.

Warm-ups w/o Emission Faults: The scan tool displays a range of 0-255. 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 ECM 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: The scan tool displays a range of 0-255. 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 information with a scan tool or a loss of power to the ECM also resets the counter to 0.

Wide Open Throttle: This parameter indicates the throttle status commanded by the control module. The scan tool will display YES is the vehicle throttle is commanded to wide open. The scan tool will display NO if the vehicle throttle is commanded to an amount less than 100 percent.