Engine 3 Data

Engine Scan Tool Data Definitions
This information will assist you in tracking down emission or driveability problems since the displays can be viewed while the vehicle is being driven. Refer to the Powertrain OBD System Check for additional information. Testing and Inspection

Engine Speed - Range (0 - 16384 RPM): Engine Speed is computed by the VCM from the fuel control reference input. It should remain close to the desired idle under various engine loads with the engine idling.

Desired Idle - Range (0 - 3187 RPM): The idle speed that is commanded by the VCM. The VCM will compensate for various engine loads to maintain the desired idle speed.

EVAP Duty Cycle - Range (0 - 100%): Indicates the EVAP canister purge solenoid duty cycle that is being commanded by the VCM.

Air/Fuel Ratio - Range (0.0:1 - 25.5:1): Indicates the calculated Air/Fuel ratio that is being commanded by the VCM.

EVAP Canister - Range (On/Off): Indicates if the EVAP system is On or Off.

EVAP Vacuum Switch - Range (On/Off): Indicates if the EVAP vacuum switch is On or Off.

EGR Duty Cycle - Range (0 - 100%): Indicates the EGR duty cycle that is being commanded by the VCM.

Actual EGR Position - Range (0 - 100%): Indicates the actual EGR position in percentage.

Desired EGR Position - Range (0 - 199.9%): Indicates the desired EGR position in percentage. EGR Sensor - Range (0 - 5.0V): Indicates the actual EGR position in voltage.

IAC Position - Range (0 - 255): The Idle Air Control (IAC) pintle position commanded from the VCM is displayed in counts. The greater the number of counts, the greater the command idle speed (air passages opened). Idle air control should respond fairly quickly to changes in engine load to maintain desired idle RPM.

Desired Idle - Range (0 - 3187 RPM): The idle speed that is commanded by the VCM. The VCM will compensate for various engine loads to maintain the desired idle speed.

ECT Sensor - Range (0 - 5.0V): The Engine Coolant Temperature (ECT) sensor is mounted in the intake manifold and sends engine temperature information to the VCM. The VCM supplies 5V 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 VCM monitors a high voltage signal which it interprets as a cold engine. As the sensor warms (internal resistance decreases), the voltage signal will decrease and the VCM will interpret the lower voltage as a warm engine.

Start Up ECT - Range -40°C to 215°C (40°F to 419°F): When the engine is started the engine coolant temperature is recorded by the VCM. This information is used to calculate the time to closed loop.

Ignition 1 - Range (0.0 - 25.5V): Indicates the condition of the ignition input to the VCM.

IAT - Range (-40°C to 151°C): The VCM converts the resistance of the Intake Air Temperature (IAT) sensor to degrees. Intake air temperature is used by the VCM to adjust fuel delivery and spark timing according to incoming air density.

Trans. Range: Indicates the current drive gear. A/B/C Range - Range (On/Off): Indicates the current state of the transmission range switches.

Cruise Mode - Range (Yes/No): Indicates if cruise control has been requested.

TCC Enable - Range (Yes/No): Indicates the status of the TCC enable output.

MPH - km/h - Range (0 - 255): Indicates in MPH and in km/h how fast the drive wheels are turning.

Brake Switch - Range (Open/Closed): Indicates the status of the brake switch.

Decel Fuel Mode - Range (Yes/No): Indicates if the VCM is in Decel Fuel Mode.

Spark Control - Range (Advance - Retard): Indicates if the VCM is commanding spark advance or spark retard.

Cam Retard - Range (2039 to -2040): Indicates the amount of Camshaft Position sensor to Crankshaft Position sensor off set.

4 WD - Range (Yes - No): Indicates if 4 wheel drive is active.

4 WD Low - Range (Yes - No): Indicates if 4 wheel drive low is active.

Ignition 1 On - Range (Yes - No): Indicates the condition of the ignition input to the VCM.

Ignition 1 Low - Range (Yes - No): Indicates the condition of the ignition input to the VCM.

Ignition 1 High - Range (0.0 - 25.5V): Indicates the condition of the ignition input to the VCM.

Power Enrichment - Range(Yes - No): Indicates if Power Enrichment mode is active.

A/C Status - Range (Yes - No): Indicates the status of the A/C system to the VCM.

A/C Request On - Range (Yes - No): Indicates if A/C has been requested.

A/C Relay - Range (On - Off): Indicates the state of the A/C relay control circuit.
A/C Engaged - Range (Yes - No): Indicates if the NC is engaged when the VCM commands the A/C On.

DTC Counter - Range (0 - 255): This indicates the total number of current Diagnostic Trouble Codes (DTCs) set. This does not necessarily mean the Malfunction Indicator Lamp (MIL) is illuminated.

Engine Run Time - Range (0:00:00 - 18:12:15) Hours: Minutes: Seconds: This is a measure of how long the engine has been running during this ignition cycle. When the engine stops running, the timer is reset to zero.