Scan Tool Data Definitions Part 1
Part1AC HIGH SIDE PRESSURE: Scan Tool Displays 0.00 to 5.00 Volts
Represents the A/C refrigerant pressure sensor signal. The amount of pressure indicates the amount of load that the A/C compressor is placing on the engine. The PCM uses this information to adjust idle and to control the cooling fans.
AC PRESSURE OUT 0F RANGE: Scan Tool Displays YES or NO.
YES displayed indicated that the PCM is monitoring an A/C Refrigerant Pressure signal voltage which is too high or too low to allow the A/C compressor clutch to engage.
AC REQUEST: Scan Tool Displays YES or NO. Indicates the state of the A/C request input circuit from the HVAC controls. The PCM uses the A/C request signal to determine whether A/C compressor operation is being requested.
ACTUAL EGR POSITION: Scan Tool Range 0% to 100%.
Represents the actual position of the EGR pintle in percent. 0% displayed indicates a fully extended pintle (EGR valve closed).
AIR FUEL RATIO: Scan Tool Range 0.0 to 25.5. Air Fuel Ratio indicates the PCM commanded value. In closed loop, Air Fuel Ratio should normally be around 14.2 - 14.7. A lower Air Fuel Ratio indicates a richer commanded mixture, which may be seen during Power Enrichment or TWC Protection modes. A higher Air Fuel Ratio indicates a leaner commanded mixture. This can be seen during Decel Fuel Mode.
BARO: Scan Tool Range 10 to 105 kPa 10.00 to 5.00 Volts.
The barometric pressure reading is determined from the MAP sensor signal monitored during key up and Wide-Open Throttle (WOT) conditions. Barometric pressure is used to compensate for altitude differences.
CHANGE OIL LAMP: Scan Tool Displays ON or OFF. Indicates the PCM commanded state of the Change Oil lamp.
COMMANDED AC: Scan Tool Displays ON or OFF. Represents the PCM commanded state of the A/C compressor clutch relay driver circuit. The A/C compressor clutch should be engaged when Commanded A/C displays ON.
COMMANDED FAN 1 / COMMANDED FAN 2: Scan Tool Displays ON or OFF.
Represents the PCM commanded state of the fan 1 (low speed) and fan 2 (high speed) control circuits.
COMMANDED GEN: Scan Tool Displays ON or OFF. OFF displayed indicates that the PCM has commanded the generator L terminal OFF.
CRUISE: Scan Tool Displays ENGAGED or DISENGAGED.
Represents the state of the Cruise Status Input form the SMCC module. Cruise should not display ENGAGED unless the vehicle is operating in a cruise control mode.
CRUISE INHIBITED: Scan Tool Displays YES or NO. YES displayed indicates that the PCM is commanding the SMCC module to inhibit cruise control operation. Should display YES at idle.
CURRENT GEAR: Scan Tool Displays numbers 1, 2, 3, or 4.
The PCM looks at Trans Range position and the gear commanded by the PCM. The actual forward gear that the Transaxle is in will be the lower of the two because the manual valve can override the PCM commanded gear.
DECEL FUEL MODE: Scan Tool Displays ACTIVE or INACTIVE.
ACTIVE displayed indicates that the PCM has detected conditions appropriate to operate in Deceleration Fuel Mode. The PCM will command deceleration fuel mode when a sudden decrease in throttle position has been detected while the vehicle is traveling over 25 mph. While in Deceleration Fuel mode, the PCM will decrease the amount of fuel delivered by entering Open Loop and decreasing the injector pulse width.
DESIRED EGR POSITION: Scan Tool Range 0% to 100%.
Represents the EGR pintle position that the PCM is commanding. Desired EGR Position should stay close to Actual EGR Position.
DESIRED IDLE SPEED: Scan Tool Range 0 to 3187 RPM.
The idle speed that is commanded by the PCM. The PCM will compensate for various engine loads based on engine coolant temperature to keep the engine at the desired idle speed.
ECT: Scan Tool Range -40°C to 151°C (-40°F to 304°F)
The Engine Coolant Temperature (ECT) sensor is mounted in the coolant stream and sends engine temperature information to the PCM. The PCM applies 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 signal voltage and interprets it 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.
EGR CLOSED VALVE PINTLE POSITION: Scan Tool Range 0.0 to 5.0 Volts.
Represents the learned voltage that the PCM uses to determine whether or not the EGR valve is fully closed (0 percent pintle position). If the EGR PWM is 0% and a difference of more than 0.4 volt between EGR Feedback and EGR Closed Valve Pintle Position is detected, DTC P1406 will set.
EGR Duty Cycle: Scan Tool Range 0% to 100%. Represents the EGR valve driver PWM signal from the PCM. A duty cycle of 0 percent indicates that no EGR flow is being commanded; a 100 percent duty cycle indicates maximum EGR flow commanded.
EGR FEEDBACK: Scan Tool Range 0.00 to 5.00 Volts.
Indicates the EGR pintle position sensor signal voltage being monitored by the PCM. A low voltage indicates a fully extended pintle (closed valve); A voltage near 5 volts indicates a fully retracted pintle (open valve).
EGR FLOW TEST COUNT: Scan Tool Range 0 to 255. Indicates the number of EGR flow test samples collected during the current ignition cycle. The maximum number of samples allowed is 1 during normal operation. If the PCM battery feed has been disconnected or a DTC P0401 has been cleared, 10 EGR flow test samples will be allowed during the next ignition cycle. This is to allow repair verification during a single ignition cycle.
EGR POSITION ERROR: Scan Tool Range 0% to 100%. Indicates the difference between Desired EGR Position and Actual EGR Position currently being monitored by the PCM. If the EGR Position Error is at an unacceptable level, DTC P1406 will set.
ENGINE HOT LAMP: Scan Tool Displays ON or OFF. Indicates the PCM commanded state of the Engine Hot lamp.
ENGINE LOAD: Scan Tool Range 0% to 100%. Engine load is calculated by the PCM from engine speed and MAF sensor readings. Engine Load should increase with an increase in RPM or air flow.
ENGINE OIL LEVEL: Scan Tool Displays OK or LOW. Indicates the oil level as determined by the Engine Oil Level switch.
ENGINE OIL LIFE: Scan Tool Range 0% to 100% Indicates the engine oil life index. The PCM calculates Engine Oil Life based upon the number of engine revolutions seen and operating conditions such as calculated oil temperature. Pressing the Oil Life Monitor reset switch will return the displayed Engine Oil Life to 100%.
ENGINE RUN TIME: Scan Tool Range 00:00:00 to 99:99:99 Hrs:Min:Sec.
Indicates the time elapsed since the engine was started. If the engine is stopped, ENGINE RUN TIME will be reset to 00:00:00.
ENGINE SPEED: Scan Tool Range 0 to 9999 RPM. Engine speed is computed by the PCM from the 3X reference input. It should remain close to desired idle under various engine loads with engine idling.
EVAP CANISTER PURGE: Scan Tool Range 0% to 100%.
Represents the PCM commanded PWM duty cycle of the EVAP Purge valve. 0% displayed indicates no purge; 100% displayed indicates full purge.
EVAP VACUUM SWITCH: Scan Tool Displays PURGE or NO PURGE.
The EVAP vacuum switch is a normally closed switch positioned in the purge line between the canister and the EVAP purge solenoid. The EVAP purge vacuum switch will open when vacuum increases to greater than 5 inches of water in the purge line. The EVAP purge vacuum switch input is used by the PCM to monitor EVAP canister purge solenoid operation and to ensure purge system integrity. The EVAP purge vacuum switch should be closed to ground with no vacuum present (0% EVAP Canister Purge PWM). With EVAP canister purge PWM at 25% or greater, the EVAP purge vacuum switch should open and purge should be indicated.
EVAP VENT SOL.: Scan Tool Displays OPEN or CLOSED
Represents the state of the EVAP Canister fresh air vent solenoid. Should be open during normal operation.
FUEL LEVEL SEN.: Scan Tool Range 0% to 100% Represents the fuel tank level sensor input to the PCM. Fuel tank level affects the EVAP system and diagnostic operation.
FUEL PUMP: Scan Tool Displays ON or OFF. Indicates the PCM commanded state of the fuel pump relay driver circuit. The fuel pump will be run at high speed to deliver more fuel volume when fuel flow or MAP is greater than a certain level, or when system voltage is less than 10 volts.
FUEL PUMP SPEED: Scan Tool Displays NORMAL or HIGH.
Indicates the status of the PWM signal to the fuel pump control circuit to the fuel pump control module.
FUEL TANK PRESSURE: Scan Tool Range 0 to 64 In. H2O
The signal from the fuel tank pressure sensor is monitored by the PCM to verify that the evaporative emissions control system is operating correctly and leaks are not present. Fuel Tank Pressure level is used extensively for EVAP purge control and EVAP system diagnostics.
FUEL TRIM CELL: Scan Tool Range 0 to 9.
Fuel trim cell is dependent upon engine speed and MAF sensor readings. A plot of RPM vs. MAF is divided into 10 cells. Fuel trim cell indicates which cell is currently active.
FUEL TRIM LEARN: Scan Tool Displays NO or YES. When conditions are appropriate for enabling long term fuel trim corrections, FUEL TRIM LEARN will display yes. This indicates that the long term fuel trim is responding to short term fuel trim. If the Fuel Trim Learn displays NO, long term fuel trim will not respond to changes in short term fuel trim.
GENERATOR PWM: Scan Tool Range 0% to 100%. Represents the field terminal input from the generator F terminal. The field PWM duty cycle indicates generator output level; a higher duty cycle indicates a higher generator output. The PCM uses the generator F terminal signal to adjust spark and lAO to compensate for variances in engine load caused by the generator.
GENERATOR LAMP: Scan Tool Displays ON or OFF. ON displayed indicates the PCM commanded state of the generator lamp / check gauges lamp due to low system voltage or a generator fault detected.
HO2S SEN. 1: Scan Tool Range 0 to 1132 mV. Represents the fuel control exhaust oxygen sensor output voltage. Should fluctuate constantly within a range between 10 mV (lean exhaust) and 1000 Mv (rich exhaust) while operating in Closed Loop.
HO2S SEN. 1: Scan Tool Displays NOT READY or READY.
Indicates the status of the fuel control exhaust oxygen sensor. The scan tool will indicate that the exhaust oxygen sensors are ready when the PCM detects a fluctuating HO2S voltage sufficient to allow closed loop operation. This will not occur unless the exhaust oxygen sensors are warmed up.
HO2S SEN. 2: Scan Tool Range 0 to 1132 mV. Represents the catalyst monitor exhaust oxygen sensor output voltage. If the catalyst is operating efficiently, the HO2S 1 signal will be far more active than that produced by the HO2S 2 sensor. If the PCM detects a level of HO2S 2 activity that indicates the catalyst is no longer operating efficiently, DTC P0420 will be set.