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/C Refrigerant Pressure-Range 0-5 Volts
- The A/C High Side displays the pressure value of the A/C refrigerant pressure sensor. The A/C refrigerant pressure 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 engine control module (ECM) 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 engine control module (ECM) 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).

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

Calculated Converter Temperature
- Represents the calculated temperature of the catalytic converter. Useful for determining if the Catalyst Monitor Test has run.

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

Cooling Fan Relay CMD
- Displays ON if the ECM is commanding the cooling fan relay On.

Crank Learned
- Displays YES if the ECM has learned the variation between crankshaft reluctor notch spacing. Learning the crankshaft is vital to correct misfire diagnostics.

Cruise Clutch Command
- Displays YES if the ECM is commanding the cruise control module clutch On.

Cruise Delta
- Displays the difference between the cruise set speed and the actual vehicle speed.

Cruise Direction Command
- Displays YES if the ECM is commanding cruise direction.

Cruise In Released State
- Displays YES if the ECM has disengaged cruise.

Cruise Resume/Accel
- Displays ON if the RES/ACCEL switch is depressed.

Cruise Set Speed
- Indicates the set vehicle cruise speed.

Cruise Set/Coast
- Displays ON if the SET/COAST switch is depressed.

Cruise Switch
- Displays ON if the CRUISE ON/OFF switch is On.

Cruise Switch-ON/OFF
- The Stepper Cruise display indicates if the engine control module (ECM) is allowing the cruise operation. The ECM has the ability to disable the cruise control under certain conditions.

Cruise Switch Voltage
- Indicates the value of the cruise control signal voltage at the ECM.

Desired Idle Speed- 0-3,187 RPM
- The engine control module (ECM) commands the idle speed. The ECM 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.

Dist. Since Code Clear
- Indicates the number of miles the vehicle has traveled since the last time the ECM DTCs were cleared.

ECT-Range -40 to +151°C (-40 to +304°F)
- The engine coolant temperature (ECT) sensor sends engine temperature information to the engine control module (ECM). The ECM 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 ECM 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 ECM will interpret the lower voltage as a warm engine.

Engine LOAD-Range 0-100 Percent
- Indicates engine load based on 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 engine control module (ECM).

Engine Oil Life Reset
- Displays YES when the oil life reset switch in the UHFB is being depressed (switch closed).

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 engine control module (ECM) 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 Large Leak
- Indicates the PASS or FAIL result of the EVAP large leak diagnostic during the EVAP diagnostic system test. NOT RAN means the test has not run this ignition and INV means the test results were invalid. A FAIL indicates a large leak is present.

EVAP Purge Solenoid
- Displays ON if the ECM is commanding a duty cycle to the EVAP purge solenoid.

EVAP Purge Solenoid DC
- Indicates the EVAP purge solenoid On-time percentage the ECM is commanding.

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

EVAP Purge Valve Leak
- Indicates the PASS or FAIL result of the EVAP purge solenoid diagnostic test during the EVAP diagnostic system test. NOT RAN means the test has not run this ignition and INV means the test results were invalid. A FAIL most likely indicates the EVAP purge solenoid is stuck open.

EVAP Small Leak
- Indicates the PASS or FAIL result of the EVAP small leak diagnostic during the EVAP diagnostic system test. NOT RAN means the test has not run this ignition and INV means the test results were invalid. A FAIL indicates a small leak is present.

EVAP Tank Vac. Slope
- Indicates the rate at which the vacuum in the fuel tank during the EVAP system small and large leak diagnostic test is decreasing (losing vacuum). Units are in millimeters of mercury per second.

EVAP Vent Blockage
- Indicates the PASS or FAIL result of the EVAP vent solenoid diagnostic test during the EVAP diagnostic system test. NOT RAN means the test has not run this ignition and INV means the test results were invalid. A FAIL most likely indicates the EVAP vent solenoid is stuck closed or an EVAP line from the vent to the fuel tank is kinked.

EVAP Vent Solenoid
- Displays ON if the ECM is commanding the EVAP vent solenoid On.

EVAP Vent Solenoid Command-Range Venting/Non-venting
- Indicates the engine control module (ECM) command of the evaporative emission (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.

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 Level Sensor
- Indicates the value of the fuel level sensor voltage at the ECM based on fuel tank level.

Fuel Pump Relay Command- Range ON/OFF
- Indicates the engine control module (ECM) 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 fuel tank pressure (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 manifold absolute pressure (MAP) sensor readings. RPM vs. MAP is broken down into 22 fuel trim cells. The fuel trim cell indicates which cell is currently active.

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

Generator F Terminal Signal-Range 0-100 Percent
- Indicates the amount of ON time the engine control module (ECM) is commanding the generator. The higher the percentage the longer the generator is being commanded ON.