Scan Tool Data Definitions

The Engine Scan Tool Data Definitions contains a brief description of all engine related parameters available on the scan tool. The list is in alphabetical order.

A/C High Side Pressure--Range 0-5 Volts: The A/C High Side displays the pressure value of the A/C refrigerant pressure sensor. The A/C High Side helps diagnose DTC P0530.

A/C High Side Pressure--Range 0-459 PSI (0-3,100 kPa): The A/C High Side displays the pressure value of the A/C refrigerant pressure sensor. The A/C High Side helps diagnose DTC P0530.

A/C Relay Command--Range On/Off: The A/C Relay represents the commanded state of the A/C clutch control relay. The A/C clutch should be engaged when the scan tool displays ON.

A/C Request Signal--Range Yes/No: A/C Request--This displays if powertrain control module (PCM) has received an A/C request from body control module (BCM) YES or NO.

Air Flow Calculated--Range 0-512 grams/second: The calculated airflow is a calculation based on manifold absolute pressure (MAP). The calculation is used in several diagnostics to determine when a sufficient engine load has been achieved to run the diagnostic.

Air Fuel Ratio--Range 0:1-25.5:1: The Air Fuel Ratio indicates the air to fuel ratio based on the oxygen sensor (O2S 1) inputs. The PCM uses the fuel trim to adjust fueling in order to maintain near an air fuel ratio of 14.7:1.

BARO--Range 11-105 kPa, 0-5.0 Volts: The barometric pressure (BARO) sensor measures the change in the intake manifold pressure which results from altitude changes. This value is updated at ignition ON and also at wide open throttle (WOT).

CKP Active Counter-7X Reference-- Range 0-255 Counts: The crankshaft position (CKP) activity counter displays whether the PCM is receiving the 7X sync pulses from the ignition module. Helpful in diagnosing DTC P0336 and Engine Cranks But Will Not Run conditions.

CMP Active Counter--Range 0-255 Counts: The camshaft position (CMP) activity counter displays the activity sent to the PCM from the CMP sensor. The counter will continually increment while the engine is running. The CMP Act. Counter is helpful in diagnosing DTC P0340.

CMP Resync Counter--Range 0-255 Counts: The camshaft position (CMP) resync counter displays the number of times the PCM had to resync with the CMP sensor. The CMP Resync Counter is helpful in diagnosing DTC P0341.

Cruise Control Active--Range Yes/No: The Stepper Cruise display indicates if the PCM is allowing the cruise operation. The PCM has the ability to disable the cruise control under certain conditions.

Cruise Release Clutch/TCC Pedal Switch--Range Applied/Unapplied: When the brake pedal is applied, the torque converter clutch (TCC) brake switch sends a signal to the PCM to disengage the TCC and disable cruise control.

Current Gear--Range 1-6: The scan tool displays the position of the transmission range switch PRNDL inputs. This information is then sent by class 2 serial data to the instrument panel cluster (IPC) to be displayed to the operator on the IPC. If a valid combination of inputs is not seen by the PCM, Invalid will be displayed.

Cycles of Misfire Data--Range 0-99 Counts: Indicates the number of current misfire cycles that are present in the engine. Increments only when misfires are current.

Desired Idle Speed-- 0-3,187 RPM: The PCM commands the idle speed. The PCM compensates for various engine loads in order to maintain the desired idle speed. The actual engine RPM speed should remain close to the desired idle under the various engine loads with the engine idling.

ECT--Range -40°C to +151°C (-40°F to +304°F): The engine coolant temperature (ECT) sensor sends engine temperature information to the PCM. The PCM supplies 5 volts to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as temperature changes. When the sensor is cold, internal resistance high, the PCM monitors a high voltage which is interpreted as a cold engine. As the sensor warms, internal resistance decreases, the voltage signal will decrease and the PCM will interpret the lower voltage as a warm engine.

Engine LOAD--Range 0-100 Percent: Indicates engine load based on manifold absolute pressure (MAP). The higher the percentage, the more load the engine is under.

Engine Oil Life Remaining--Range 0-100 Percent: This display represents the engine oil life index that is calculated and maintained by the PCM.

Engine Oil Pressure Switch--Range Low/OK: The engine oil pressure switch sends an input to the PCM to indicate whether the engine oil pressure is Low or OK.

Engine Run Time--Range 0:00:00-18:12:15 hours:minutes:seconds: The engine run time is a measure of how long the engine has been running. When the engine stops running the timer resets to zero.

Engine Speed--Range 0-16,384 RPM: Engine Speed is computed by the PCM from the fuel control reference input. The engine speed should remain close to desired idle under the various engine loads with the engine idling.

EVAP Purge Solenoid Command--Range 0-100 Percent: Indicates the PCM command of the evaporative emission (EVAP) purge valve solenoid in order to control the evaporative emission canister purge function. At 0 percent the valve is commanded fully closed. 100 percent implies that the valve is fully open.

EVAP Vent Solenoid Command-- Range Venting/Non-venting: Indicates the PCM command of the EVAP vent solenoid allowing fresh outside air to the EVAP canister during the purge mode. The EVAP vent solenoid allows the diagnostic to pull a vacuum on the fuel tank by closing the vent solenoid.

FC Relay 1 Command--Range On/Off: The fan control (FC) relay is commanded by the PCM. FC relay 1 displays the command as ON or OFF.

Fuel Level Sensor-- Range 0-100 Percent: The fuel level sensor monitors the fuel level in the tank. Several of the Enhanced EVAP System diagnostics are dependent upon the correct fuel level.

Fuel Pump Relay Command-- Range ON/OFF: Indicates the PCM command of the fuel pump relay.

Fuel Tank Pressure Sensor-- Range -25.89 to +32.45 mm Hg: The fuel tank pressure (FTP) sensor measures the difference between the pressure or vacuum in the fuel tank and the outside air pressure.

Fuel Tank Pressure Sensor--Range - 0.0 to 5.0 Volts: The FTP sensor measures the difference between the pressure or the vacuum in the fuel tank and the outside air pressure. When the air pressure in the fuel tank equals the outside air pressure, the output voltage of the sensor is 1.3-1.7 volts.

Fuel Trim Cell--Range 0-22: A fuel trim cell depends upon the engine speed and the MAP sensor readings. RPM vs. MAP is broken down into 22 fuel trim cells. The fuel trim cell indicates which cell is currently active.

Fuel Trim Index--Range 0-255 (-100 to +100 Percent): The fuel trim index is a combined value of EVAP Purge learn memory, Long Term Fuel Trim, and Short Term Fuel Trim and is used by the PCM as part of the entry criteria of the fuel trim diagnostic. Results of the actual Fuel Trim Index are compared to a minimum and maximum calibration to pass or fail the Fuel Trim Diagnostic.

Generator L Terminal Signal--Range Inactive/Active: The generator L terminal indicates whether the PCM is allowing the generator to operate. The PCM can disable the generator under certain conditions to ease starting. Inactive indicates that the PCM is allowing generator operation, while active indicates that the PCM is not allowing generator operation.

Generator F Terminal Signal--Range 0-100 Percent: Indicates the amount of ON time the PCM is commanding the generator. The higher the percentage the longer the generator is being commanded ON.

HO2S 1--Range 0-1132 mV: The front heated oxygen sensor (HO2S 1) reading represents the exhaust oxygen sensor output voltage. This voltage will fluctuate constantly between 100 mV, lean exhaust, to 900 mV, rich exhaust, when operating in a Closed Loop.

HO2S 2-- Range 0-1132 mV: The rear heated oxygen sensor (HO2S 2) represents the exhaust oxygen output voltage past the catalytic converter. This voltage remains inactive, or the voltage will appear lazy within a range of 100 mV, lean exhaust, and 900 mV, rich exhaust, when the system is operating in a Closed Loop.

HO2S 1 Heater Current: This parameter displays the current through the control module when the HO2S sensor 1 heater is commanded ON by the control module. HO2S 1 Heater 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 Current: This parameter displays the current through the control module when the HO2S sensor 2 heater is commanded ON by the control module. HO2S 2 Heater 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.

IAC Position--Range 0-255 Counts: The idle air control (IAC) pintle position command from the PCM is displayed in counts. The higher the counts read, the more the commanded idle speed is. The idle air control responds fairly quickly to changes in the engine load in order to maintain the desired idle RPM.

IAT Sensor--Range -40°C to +151°C (-40°F to +304°F): The PCM converts the resistance of the intake air temperature (IAT) sensor to degrees in the same manner as the ECT sensor. Intake air temperature is used by the PCM to adjust fuel delivery and spark timing according to incoming air density.

Ignition 1 Signal--Range 0-25.5 Volts: The ignition volts represents the system voltage measured by the PCM at the ignition feed circuit.

Injector PWM -- Range 0-999.9 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.

Injector 1-4 Command-- Range 0-999.9 mS: Indicates the PCM command on the fuel injectors. The higher the number the longer the PCM is commanding the fuel injectors ON.

Knock Retard--Range 0-90 Degrees: The Adaptive Knock Retard indicates the long term amount of the spark advance the PCM removes from the ignition control (IC). The PCM responds to the knock sensor (KS) signal.

Long Term FT--Range 0-255 (-100 to 100 Percent): The Long Term FT is derived from the Short Term FT value. The Long Term FT is used for the long term correction of the fuel delivery. A value of the 128 counts, 0 percent, indicates that the fuel delivery requires no compensation in order to maintain a 14.7:1 air to fuel ratio. A value below 128 counts means that the fuel system is too rich and the fuel delivery is being reduced. The PCM is decreasing the injector pulse width. A value above 128 counts indicates that a lean condition exists for which the PCM is compensating.

Loop Status--Range Open/Closed: A Closed Loop displayed indicates that the PCM is controlling the fuel delivery according to the oxygen sensor (O2S 1) voltage. The PCM controls the fuel delivery air to fuel ratio as close to 14.7:1 as possible.

MAP Sensor--Range 11-105 kPa, 0-5 Volts: The manifold absolute pressure (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.

MIL Command--Range ON/OFF: Indicates whether the PCM is commanding the MIL ON or OFF.

Misfire Current #1-4--Range 0-255 Counts: Indicates the number of current misfires that are present in the indicated cylinder. Increments only when misfire is current.

Misfire History #1-4--Range 0-255 Counts: Indicates the number of misfires that have occurred after 195 current misfires have been counted. The current misfire counter will add the misfires to the history misfire counter after 195 total misfires have taken place. If 1 cylinder is misfiring, the misfiring current counter will have 195 misfires counted before adding to its history counter. If 2 cylinders are misfiring, the misfiring current counters will add to their history counters after 97 misfires. Increments only after a misfire diagnostic trouble code (DTC) has been set.

Med. Resolution Resync Counter--Range 0-255 Counts: The medium resolution resync counter displays the number of times the PCM had to resync the crankshaft position (CKP) sensor. The med. resolution resync counter is helpful in diagnosing DTC P0335.

Number of DTCs--Range 0-255: The number of current DTCs indicates the total number of current diagnostic trouble codes set. These current DTCs set does not necessarily mean that the malfunction indicator lamp (MIL) is illuminated.

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

Short Term FT--Range 0-255 (-100 to +100 Percent): Short Term FT represents a short term correction to fuel delivery by the PCM in response to the amount of time the oxygen sensor voltage spends above or below the 450 mV threshold. If the oxygen sensor has mainly been below 450 mV, indicating a lean air/fuel mixture, Short Term FT will increase to tell the PCM to add fuel. If the oxygen sensor voltage stays mainly above the threshold, the PCM will reduce fuel delivery to compensate for the indicated rich condition.

Spark--Range 64 to -64 Degrees: This is a display of the spark advance ignition control (IC) calculation which the PCM is programming in the ignition system. The desired spark advance is computed using data such as engine temperature, RPM, engine load, vehicle speed, and operating mode.

Start Up ECT: Indicates the engine coolant temperature at engine start up.

TP Sensor--Range 0-100 Percent: The PCM computes the throttle position (TP) from the TP sensor voltage input. The TP angle will auto zero to 0 percent at idle when the TP voltage is below 0.90 volts. The TP angle will read 100 percent at wide open throttle (WOT).

TP Sensor--Range 0.0-0.5 Volts: The PCM uses the throttle position (TP) sensor to determine the amount of the throttle demanded by the operator of the vehicle. The TP sensor reads between 0.36-0.96 volts at idle to above 4 volts at wide open throttle (WOT).

Vehicle Speed Sensor--Range 0-255 km/h, 0-255  mph: The vehicle speed sensor signal is converted into km/h/mph for display. The vehicle speed output from the PCM is 4,000 pulses per mile. The scan tool uses the class 2 serial data from the PCM to obtain vehicle speed, while the instrument panel cluster, cruise control module and multi-function alarm module use the 4,000 ppm output.

VTD Fuel Disable--Range Active/Inactive: Indicates if the vehicle theft deterrent (VTD) module has received proper information to enable or disable fuel.

VID Auto. Learn Timer--Range Active/Inactive: The Theft System Learn Mode is used to indicate when the PCM is ready to learn the password during the Password Learn Procedure. More information is located in the Password Learn Procedure portion of the service manual.