The 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.

Air Conditioning: The parameter will indicate ON whenever the A/C Idle-Up signal is received by the PCM from the A/C compressor control module. This allows the PCM to adjust the engine idle to maintain acceptable engine performance.

BARO: The scan tool range is 0-125 kPa. The barometric pressure (BARO) sensor measures the changes in atmospheric pressure. This parameter will read approximately 95 to 105 kPa at sea level.

Battery Voltage: This parameter indicates battery positive voltage inputted from the ignition relay to the PCM.

Calculated IAC Air Flow: The calculated idle air control (IAC) air flow is the volume of air the PCM determines is necessary to maintain the desired engine idle speed. The PCM uses information from the TP sensor, the MAF sensor, and the engine speed in order to calculate the required IAC valve pintle position. The scan tool displays the volume of air in liters per minute (L/Min) or cubic feet per minute (FT3/Min).

CMP Active Counter: The scan tool range is 0 to 255 counts. When the CMP sensor is supplying engine reference signals to the PCM, the scan tool will indicate an increasing count. The count calue will increase from 0 counts to as many as 255 counts, and then restart at 0 counts.

Decel. Fuel Cutoff: The Decel. Fuel Cutoff parameter indicates the status of the fuel injection system. When the PCM cuts off the injectors, the parameter reads ACTIVE. The parameter reads INACTIVE at all other times.

Desired Idle Speed: The Desired Idle Speed is a PCM internal parameter which indicates the RPM requested idle speed. The engine speed should remain close to desired idle under various engine loads with the engine idling.

Engine Speed: The scan tool range is 0-10,000 RPM. The PCM computes engine speed from the ignition reference pulses from the CMP sensor.

ECT: The scan tool range is -40°C to +120°C (-40°F to +250°F). The ECT sensor is a thermistor which changes internal resistance as its temperature changes. When the sensor is cold (internal resistance high), the PCM monitors a high signal voltage and interprets the voltage as a cold engine. As the sensor warms (internal resistance decreases), the voltage signal decreases and the PCM interprets the lower voltage as a warm engine.

Engine Load: The scan tool range is 0 percent to 100 percent. This parameter indicates engine load based on manifold absolute pressure. A higher percentage indicates a greater load on the engine.

EVAP Density Trim: The scan tool range is 0 to 128 counts. This parameter indicates EVAP system purge concentration and is indicated in counts.

EVAP Duty Cycle: The scan tool range is 0 percent to 100 percent. The EVAP Duty Cycle specifies the EVAP Canister Purge Valve ON (valve open) time rate within a certain set cycle. Zero percent means that the purge valve is completely closed while a 100 percent is a fully open valve.

EVAP Tank Pres. Control Solenoid: The EVAP Tank Pressure Control Solenoid Valve is Open when the valve is turned ON by the PCM and Closed when the valve is turned OFF.

EVAP Vent Solenoid: This parameter indicates when the PCM turns ON the EVAP Canister Vent Solenoid.

EGR Solenoid Command: The scan tool range is 0 percent to 100 percent. The EGR Solenoid Command specifies the EGR Valve ON (valve open) time rate within a certain set cycle. Zero percent means that the valve is completely closed while a 100 percent is a fully open valve.

Fan Request: This parameter indicates the status of the PCM command to the A/C condenser fan relay. The PCM turns ON the A/C condenser fan relay when the A/C is operating. The PCM also turns ON the relay when the ECT sensor indicates that the engine coolant temperature is more than 110°C (223°F).

Fuel Level: The scan tool range is 0 to 100 percent. This parameter indicates approximate fuel level in the fuel tank. However, on models with smaller fuel tanks, the indicated fuel level may be 70 percent even when the fuel tank is full.

Fuel Pump: This parameter indicates ON when the PCM commands the fuel pump ON through the fuel pump relay. The PCM energizes the relay for 3 seconds when the ignition is turned ON, and continuously energizes the relay when receiving CMP sensor reference pulses.

Fuel Tank Pressure: The scan tool range is -60.0 to 61.5 mmHg. This parameter indicates the pressure in the fuel tank and is expressed with respect to the barometric pressure. When the fuel tank pressure is equal to the barometric pressure, the scan tool indicates 0 mmHg.

High Electrical Load Indicator: 

HO2S 1: The scan tool range is 0-1275 mV. The HO2S 1 parameter represents the sensors output voltage. The voltage of a properly operating sensor fluctuates constantly between 10 mV (lean exhaust) and 1000 mV (rich exhaust).

HO2S 2: The scan tool range is 0-1275 mV. The HO2S 2 parameter represents the output voltage of the post catalytic converter sensor. This voltage will remain inactive or appear lazy within a range of 100 mV (lean exhaust) and 900 mV (rich exhaust) when the system is operating in closed loop.

HO2S 1 Ready: YES indicates that the oxygen sensor is warmed up and is capable of sending useful voltage readings to the PCM. NO indicates a cold (not ready) oxygen sensor.

HO2S 2 Ready: YES indicates that the oxygen sensor is warmed up and is capable of sending useful voltage readings to the PCM. NO indicates a cold (not ready) oxygen sensor.

IAC Motor Command: The scan tool range is 0 to 100 percent. This scan tool parameter indicates the amount of air flow the IAC motor is commanding through the bypass air passage.

IAT: The scan tool range is -40°C to +120°C (-40°F to +250°F). The PCM converts the resistance of the intake air temperature sensor to degrees. The PCM uses the intake air temperature (IAT) in orderto adjust fuel delivery and spark timing according to incoming air density.

Injector PWM: This parameter indicates the time of the fuel injector valve opening.

Long Term FT: The scan tool displays percentage. The 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 (decreased injector pulse width). A positive value significantly more than 0 percent indicates that a lean condition exists and the PCM compensates by adding fuel (increased injector pulse width). Fuel trim values at maximum authority may indicate an excessively rich or lean system.

Loop Status: The scan tool displays Open Loop or Closed Loop. Closed Loop indicates that the PCM is controlling fuel delivery according to oxygen sensor voltage. Open Loop indicates that the PCM ignores the oxygen sensor voltage and bases the amount of fuel to be delivered on the TP sensor, the ECT sensor, and MAP sensor inputs.

MAF: This parameter indicates the quantity of air entering the engine through the MAF sensor. This volume of air is measured in grams per second (g/s).

MAP: The scan tool range is 0-125 kPa/0.0-5.0 volts. The manifold absolute pressure (MAP) sensor measures the change in the intake manifold pressure from engine load, and speed changes. As intake manifold pressure increases, the intake vacuum decreases resulting in a higher kPa reading.

Power Steering Switch: The scan tool will display an ON signal whenever the steering wheel is turned right or left far enough to increase the power steering fluid pressure above a specified amount. This signal enables the PCM to adjust the engine idle in order to maintain acceptable engine performance.

Short Term FT: The scan tool displays percentage. The 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 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.

Spark: The scan tool range is -1 to 60 degrees. This displays the PCM controlled value that is being used to control the spark timing.

Starter Switch: This parameter displays Cranking when the PCM is receiving a signal indicating that the engine starter motor is cranking. The scan tool will display Released when the ignition is ON and when the engine is running.

Total Fuel Trim: The value of Total Fuel Trim is obtained by putting the values of Short Term Fuel Trim and Long Term Fuel Trim together. This value indicates how much correction is necessary in order to keep the air/fuel mixture at the stoichiometrical 14.7:1 ratio.

TP Sensor: The scan tool displays 0-5 volts. Closed throttle displays about 1 volt and wide open throttle displays about 3.5 volts.

TP Angle: The scan tool displays 0 to 100 percent. Closed throttle displays 0 percent and wide open throttle displays near 100 percent.

Vehicle Speed: The scan tool range is 0-200 km/h (0-125 MPH). The powertrain control module (PCM) receives reference pulses from the vehicle speed sensor (VSS) and converts them into km/h and MPH for display.