Data Definitions and Ranges
ENGINE TECH 2 DATA DEFINITIONS AND RANGESA/C CLUTCH - Tech 2 Displays ON or OFF -
Indicates whether the ECM has commanded the A/C clutch ON. Used in A/C system diagnostic.
A/C REQUEST - Tech 2 Displays YES or NO -
Indicates the state of the A/C request input circuit from the HVAC controls. The ECM uses the A/C request signal to determine whether A/C compressor operation is being requested.
AIR/FUEL RATIO - Tech 2 Range 0.0-25.5 -
Air/fuel ratio indicates the ECM commanded value. In closed loop, the air/fuel ratio should normally be displayed 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 deceleration fuel mode.
AP1 -Tech 2 Range 0-5 V -
AP (accelerator pedal) angle is computed by the ECM from the AP sensor voltage. AP angle should display "0.35-0.95 V" at idle and "4.05-4.65 V" at wide open throttle.
AP2 -Tech 2 Range 0-5 V -
AP (accelerator pedal) angle is computed by the ECM from the AP sensor voltage. AP angle should display "0.35-0.95 V" at idle and "4.05-4.65 V" at wide open throttle.
AP3 -Tech 2 Range 0-5 V -
AP (accelerator pedal) angle is computed by the ECM from the AP sensor voltage. AP angle should display "0.35-0.95 V" at idle and "4.05-4.65 V" at wide open throttle.
DESIRED IDLE - Tech 2 Range 0-3187 RPM -
The idle speed that the ECM is commanding. The ECM will compensate for various engine loads based on engine coolant temperature, to keep the engine at the desired speed.
ECT - (Engine Coolant Temperature) Tech 2 Range -40 °C to 151 °C (-40 °F to 304 °F) -
The engine coolant temperature (ECT) is mounted in the coolant stream and sends engine temperature information to the ECM. The ECM 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 (high resistance), the ECM monitors a high signal voltage and interprets that as a cold engine. As the sensor warms (decreasing resistance), the voltage signal will decrease and the ECM will interpret the lower voltage as a warm engine.
ENGINE LOAD - Tech 2 Range 0%-100% -
Engine load is calculated by the ECM from engine speed and MAF sensor readings. Engine load should increase with an increase in RPM or air flow.
ENGINE RUN TIME - Tech 2 Range 00:00:00-99:99:99 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 - Range 0-9999 RPM -
Engine speed is computed by the ECM from the 58X reference input. It should remain close to desired idle under various engine loads with engine idling.
EVAP PURGE - Tech 2 Range 0%-100% -
Represents the ECM commanded PWM duty cycle of the EVAP purge solenoid valve. "0%" displayed indicates no purge; "100%" displayed indicates full purge.
FUEL PUMP - Tech 2 Displays ON or OFF -
Indicates the ECM commanded state of the fuel pump relay driver circuit.
HO2S BANK 1, SEN. 1 - Tech 2 Range 0-1132 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 BANK 1, SEN. 2 - Tech 2 Range 0-1000 mV -
Monitors the exhaust oxygen sensor output voltage. The ECM monitors the operating efficiency of catalytic converter by comparing the output voltages of sensor 1 and sensor 2 in this bank. If the catalytic converter is operating efficiently, the output voltage of sensor 1 will give a greater fluctuation than that of sensor 2. If the ECM detects an abnormal level of voltage fluctuation from sensor 2, a DTC P0420 will be set, indicating that the catalytic converter for this bank is no longer operating efficiently.
HO2S BANK2, SEN. 1 -Tech 2 Range 0-1132 mV-
Represents the fuel control exhaust oxygen sensor output voltage. Should fluctuate constantly within a range between 10mV (lean exhaust) and 1000 mV (rich exhaust) while operating in closed loop.
HO2S BANK 2, SEN. 2-Tech 2 Range 0-1000 mV-
Monitors the exhaust oxygen sensor output voltage. The ECM monitors the operating efficiency of catalytic converter by comparing the output voltages of sensor 1 and sensor 2 in this bank. If the catalytic converter is operating efficiently, the output voltage of sensor 1 will have a greater fluctuation than that of sensor 2. If the ECM detects an abnormal level of voltage fluctuation from sensor 2, a DTC P0430 will be set, indicating that the catalytic converter for this bank is no longer operating efficiently.
HO2S BANK 1, SEN. 1-Tech 2 Displays NOT READY or READY-
Indicates the status of the exhaust oxygen sensor. The Tech 2 will indicate that the exhaust oxygen sensor is ready when the ECM detects a fluctuating HO2S voltage sufficient to allow closed loop operation. This will not occur unless the exhaust oxygen sensor is warmed up.
HO2S BANK 2, SEN. 1 - Tech 2 Displays NOT READY or READY -
Indicates the status of the exhaust oxygen sensor. The Tech 2 will indicate that the exhaust oxygen sensor is ready when the ECM detects a fluctuating HO2S voltage sufficient to allow closed loop operation. This will not occur unless the exhaust oxygen sensor is warmed up.
HO2S WARM UP TIME BANK 1, SEN. 1/BANK 1, SEN 2/BANK 2 SEN. 1/BANK 2 SEN. 2 -Tech 2
Range 00:00:00-99:99:99 HRS:MIN:SEC -
Indicates warm-up time for each HO2S. The HO2S warm-up time is used for the HO2S heater test. The ECM will run the heater test only after a cold start (determined by engine coolant and intake air temperature at the time of start-up) and only once during an ignition cycle. When the engine is started the ECM will monitor the HO2S voltage. When the HO2S voltage indicates a sufficiently active sensor, the ECM looks at how much time has elapsed since start-up. If the ECM determines that tool much time was required for the HO2S to become active, a DTC will set. If the engine was warm when started, HO2S warm-up will the display "00:00:00".
IAT (INTAKE AIR TEMPERATURE) - Tech 2 Range -40 °C to 151 °C (-40 °F to 304 °F) -
The ECM converts the resistance of the intake air temperature sensor to degrees. Intake air temperature (IAT) is used by the ECM to adjust fuel delivery and spark timing according to incoming air density.
IGNITION Voltage - Tech 2 Range 0-25.5 Volts -
This represents the system voltage measured by the ECM at its ignition feed.
INJ. PULSE BANK 1/INJ. PULSE BANK 2 - Tech 2 Range 0-1000 msec. -
Indicates the amount of time the ECM is commanding each injector "ON" during each engine cycle. A longer injector pulse width will cause more fuel to be delivered. Injector pulse width should increase with increased engine load.
LONG TERM FUEL TRIM BANK 1/BANK 2 -
The long term fuel trim is derived from the short term fuel trim values and represents a long term correction of fuel delivery for the bank in question. A value of 0% indicates that fuel delivery requires no compensation to maintain the ECM commanded air/fuel ratio. A negative value significantly below 0% indicates that the fuel system is rich and fuel delivery is being reduced (decreased injector pulse width). A positive value significantly greater than 0% indicates that a lean condition exists and the ECM is compensating by adding fuel (increased injector pulse width). Because long term fuel trim tends to follow short term fuel trim, a value in the negative range due to canister purge at idle should not be considered unusual. Fuel trim values at maximum authority may indicate an excessively rich or lean system.
Open/Closed Loop - Tech 2 Displays OPEN or CLOSED -
"CLOSED" indicates that the ECM is controlling fuel delivery according to oxygen sensor voltage. In "OPEN" the ECM ignores the oxygen sensor voltage and bases the amount of fuel to be delivered on TP sensor, engine coolant, and MAF sensor inputs only.
MAF - Tech 2 Range 0.0-512 g/s -
MAF (mass air flow) is the MAF input frequency converted to grams of air per second. This indicates the amount of air entering the engine.
MIL - Tech 2 Displays ON or OFF -
Indicates the ECM commanded state of the malfunction indicator lamp.
MISFIRE CUR. CYL. #1 /#2 /#3 /#4 / #5 / #6 - Tech 2 Range 0-255 Counts -
The misfire current counters increase at a rate according to the number of the possible misfires being detected on each cylinder. The counters may normally display some activity, but the activity should be nearly equal for all the cylinders.
MISFIRE CUR. CYL. #1 /#2 /#3 /#4 / #5 / #6 - Tech 2 Range 0-65535 Counts -
The misfire history counters display the relative level of misfire that has been detected on each cylinder. The misfire history counters will not update or show any activity until a misfire DTC (P0300) has become active.
SPARK - Tech 2 Range -64° to 64° -
Displays the amount of spark advance being commanded by the ECM on the IC circuit.
START-UP ECT - Tech 2 Range -40 °C to 151 °C (-40 °F to 304 °F) -
Indicates the engine coolant temperature at the time that the vehicle was started. Used by the HO2S diagnostic to determine if the last start-up was a cold start.
START-UP IAT - Tech 2 Range -40 °C to 151 °C (-40 °F to 304 °F) -
Indicates the intake air temperature at the time that the vehicle was started. Used by the HO2S diagnostic to determine if the last start-up was a cold start.
TOTAL MISFIRE CURRENT COUNT - Tech 2 Range 0-255 -
Indicates the total number of cylinder firing events that were detected as being misfires during the last 200 crankshaft revolution sample period.
TP - Tech 2 Range 0-5 V -
TP (throttle position) angle is computed by the ECM from the TP sensor voltage. TP angle should display "about 0.5 V" at idle and "about 4.23 V" at wide open throttle.
VIM Solenoid - Tech 2 Displays ON or OFF -
Indicates the ECM commanded state of the VIM (Variable Intake Manifold) solenoid.
VVT ACTUAL TIMING (Bank 1, 2) - Tech 2 Range -5 - 40 degree -
Indicates the phase angle of the camshaft toward retard side.
ACTUAL FUEL PRESSURE (HIGH) - Tech 2 Range 0 - 14 MPa -
Indicates the actual fuel pressure of the high pressure side. The value should display 5MPa at idle and between 5 to 10 MPa at normal driving condition.
ACTUAL LOW FUEL PRESSURE - Tech 2 Range 0 - 650kPa -
Indicates the actual fuel pressure of the low pressure side. The value should display 350kPa at normal condition and 550 kPa under the hot condition.
SHORT TERM FUEL TRIM (Bank 1, 2) - Tech 2 Range -40 - 20% -
Indicates the short term fuel trim value.
FUEL PRESSURE REGULATOR DUTY - Tech 2 Range 0 - 100% -
Indicates the commanded state of the fuel pressure regulator. The ECU sends the duty signal to the fuel pressure regulator and controls fuel pressure of the high pressure side.
LOW FUEL PRESSURE REGULATOR DUTY - Tech 2 Range 0 - 100% -
Indicates the commanded state of the fuel pump controller. The ECU sends the duty signal to the fuel pump controller and controls fuel pressure of the low pressure side.