Scan Tool Data Definitions Part 1

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 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.

4WD Signal: The scan tool displays Enabled or Disabled. The transfer case should be in four wheel drive (4WD) when the scan tool displays Enabled.

4WD Low Signal: The scan tool displays Enabled or Disabled. The transfer case should be in four wheel drive (4WD) low when the scan tool displays Enabled.

A/C Compressor Cycling Switch: The scan tool displays Open or Closed. This parameter displays the state of the A/C compressor cycling switch. The A/C compressor cycling switch is a normally closed switch.

A/C Relay Command: The scan tool displays ON or OFF. This parameter displays the powertrain control module (PCM) commanded state of the A/C clutch control relay. When the scan tool displays ON, the A/C clutch should be engaged.

A/C Sec. High Press. Switch: The scan tool displays Open or Closed. This parameter displays the state of the A/C secondary high pressure switch. The A/C secondary high pressure switch is normally open.

A/C Request: The scan tool displays Yes or No. The A/C Request displays the state of the A/C request input circuit from the heating, ventilation, and air conditioning (HVAC) controls. The powertrain control module (PCM) uses the A/C request signal in order to determine whether the A/C compressor operation is being requested.

Actual EGR Position: The scan tool displays a range of 0-100 percent. The PCM supplies a pulse width modulated (PWM) duty cycle to control the exhaust gas recirculation (EGR) valve. Zero percent indicates no EGR flow. One hundred percent indicates full EGR flow.

Air Fuel Ratio: The scan tool displays the ratio of the air to fuel. A typical ratio is about 14.7:1.

AIR Pump Relay Command: The scan tool displays ON or OFF. The scan tool displays ON when the powertrain control module (PCM) grounds the secondary air injection (AIR) pump relay control circuit. The scan tool displays OFF when the PCM disables the ground circuit.

BARO: The scan tool displays a range of 10-105 kPa and 0.00-5.00 volts. The barometric pressure (BARO) reading is determined from the manifold absolute pressure (MAP) sensor signal. The powertrain control module (PCM) monitors the MAP signal during key up or wide-open throttle (WOT) conditions. The barometric pressure compensates for altitude differences.

Brake Pedal Switch: The scan tool displays Applied or Released. This parameter indicates the state of the brake switch circuit input. The scan tool displays Applied when you apply the vehicle brakes. The scan tool displays Released when you release the vehicle brakes.

CMP Sensor High to Low: The scan tool displays 0-65,535 counts. The counts increment as the powertrain control module (PCM) detects the camshaft position (CMP) sensor signal voltage going from high to low.

CMP Sensor Low to High: The scan tool displays 0-65,535 counts. The counts increment as the powertrain control module (PCM) detects the CMP signal voltage going from low to high.

Clutch Pedal Switch: The scan tool displays Depressed or Released. The scan tool displays Depressed when you apply the vehicle clutch. The scan tool displays Released when you release the clutch pedal.

Cold Start Up: The scan tool displays Yes or No. A cold start-up is when the engine coolant temperature (ECT) rises above a predetermined temperature during an ignition cycle. The next ignition cycle the ECT should be below a predetermined temperature. Also the ECT and the intake air temperature (IAT) are less than 50°C (122°F) and are within 3°C (5°F) of each other at start-up. When the above is true, the scan tool displays Yes.

Cruise On/Off Switch: The scan tool displays Yes/No. When the cruise control module is enabled, the scan tool displays Yes.

Current Gear: The scan tool displays 0-4. The scan tool displays which gear the transmission is in. An illegal transmission position displays 9.

Cycles of Misfire Data: The scan tool displays a range of 0-100. The powertrain control module (PCM) counts the number of misfire tests during 200 engine revolutions.

Desired IAC Airflow: The scan tool displays a range of 0-64 grams per second (g/s). This parameter displays a calculated airflow within the idle air control (IAC) passage.

Desired IAC Position: The scan tool displays a range of 0-255 counts. This parameter displays the desired idle air control (IAC) position as requested by the powertrain control module (PCM).

Desired EGR Position: The scan tool displays 0-100 percent. This parameter displays the desired position of the exhaust gas recirculation (EGR) pintle as requested by the powertrain control module (PCM). This parameter should be very close to actual EGR position.

Desired Idle Speed: The scan tool displays a range of 0-3,187 RPM. The powertrain control module (PCM) commands the desired idle speed. The PCM compensates for various engine loads based on ECT in order to keep the engine at the desired speed.

DTC Set This Ignition: The scan tool displays Yes or No. This parameter indicates if a diagnostic trouble code (DTC) set during the current ignition cycle.

ECT Sensor: The scan tool displays a range of -39 to +140°C (-38 to +284°F). The powertrain control module (PCM) applies 5.0 volts to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as the engine temperature changes. When the sensor is cold, internal resistance high, the PCM senses 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.

EGR Learned Minimum Position: The scan tool displays 0-5.0 volts. This display represents the voltage that the powertrain control module (PCM) uses in order to determine whether or not the EGR valve is closed. The voltage displayed will be the closed position of the EGR pintle learned by the PCM.

EGR Position Sensor: The scan tool displays 0-5.0 volts. This parameter displays the actual EGR pintle position in voltage.

Engine Load: The scan tool displays a range of 0-100 percent. The powertrain control module (PCM) calculates the engine load from engine speed and mass air flow (MAF) sensor readings. The engine load increases with an increase in RPM or airflow.

Engine Oil Life Remaining: The scan tool displays 0-100 percent. This display represents the engine oil life index that is calculated and maintained by the powertrain control module (PCM).

Engine Run Time: The scan tool displays Hours, Minutes, Seconds. This displays the amount of engine run time for the current ignition cycle. When you cycle the ignition OFF, the timer resets to zero.

Engine Speed: The scan tool displays a range of 0-10,000 RPM. The powertrain control module (PCM) computes engine speed from the ignition reference pulses. The engine speed should remain close to desired idle under various engine loads with the engine idling.

EVAP Purge Solenoid Command: The scan tool displays a range of 0 -100 percent. The powertrain control module (PCM) supplies a pulse width modulated (PWM) duty cycle to control the evaporative emission (EVAP) purge solenoid valve. 0 percent indicates no purge. 100 percent indicates full purge.

EVAP Vent Solenoid Command: The scan tool displays Venting or Not Venting. The evaporative emission (EVAP) canister vent valve is normally open. The powertrain control module (PCM) commands the EVAP canister vent valve closed, during testing of the EVAP system.

Fuel Level Sensor: The scan tool displays 0-5.00 volts. The scan tool displays below 1.0 volt for an empty tank, and close to 2.5 volts for a full tank.

Fuel Tank Level Remaining: The scan tool displays in liters or gallons the amount of fuel remaining in the fuel tank.

Fuel Tank Level Remaining: The scan tool displays 0-100 percent. The scan tool displays in percentage the amount of fuel remaining in the fuel tank.

Fuel Tank Pressure Sensor: The scan tool displays in -32.7 to +13.96 mm/Hg or -17.4 to +7.5 inch H2O. This parameter indicates the pressure vacuum inside of the fuel tank. A negative value indicates a vacuum. A positive value indicates a pressure.

Fuel Tank Pressure Sensor: The scan tool displays 0-5.0 volts. The scan tool displays in voltage the pressure inside of the fuel tank.

Fuel Tank Rated Capacity: The scan tool displays the capacity of the fuel tank in liters or gallons.

Fuel Trim Cell: The scan tool displays a range of 0-23. The powertrain control module (PCM) determines from the manifold absolute pressure (MAP) and RPM inputs which fuel trim cell to operate the engine in. The fuel trim cell displayed on the scan tool is the cell that the engine is operating under.

Fuel Trim Learn: The scan tool displays Enabled or Disabled. When conditions are appropriate for enabling long term fuel trim corrections, the scan tool displays Enabled. This indicates that the long term fuel trim is responding to the short term fuel trim. If the scan tool displays Disabled, then long term fuel trim will not respond to changes in short term fuel trim.

Generator L- Terminal Signal: The scan tool displays Active or Inactive. The scan tool displays inactive if the powertrain control module (PCM) does not detect a correct voltage on the L-terminal circuit. The scan tool displays active under normal operating conditions.

Generator F- Terminal Signal: The scan tool displays Active or Inactive. The scan tool displays inactive if the powertrain control module (PCM) does not detect a correct voltage on the F-terminal circuit. The scan tool displays active under normal operating conditions.