Engine
ENGINE SPEED: Range 0-9999 RPMEngine speed is computed by the Powertrain Control Module (PCM) from the distributor reference input (low resolution circuit). It should remain close to desired idle under various engine loads with engine idling.
DESIRED IDLE: Range 0-3187 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 speed.
ENG COOL TEMP: Range 40°C to 151°C, -40°F to 304°F
The Engine Coolant Temperature (ECT) sensor is mounted in the coolant pump and sends engine temperature information to the PCM. The PCM 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 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.
INTAKE AIR TEMP: Range -40°C to 151°C, -40°F to 304°F
The PCM converts the resistance of the intake air temperature sensor to degrees. Intake Air Temperature (IAT) is used by the PCM to adjust fuel delivery and spark timing according to incoming air density.
MAP: Range 10-105 kPa/0-5 Volts
The Manifold Absolute Pressure (MAP) sensor measures the change in the intake manifold pressure from engine load and speed changes. As intake manifold pressure increases, the air density in the intake manifold also increases and additional fuel is required.
BARO: Range 10-105 kPa/0-5 Volts
The BARO reading displayed is determined from the MAP sensor at ignition "ON," engine "OFF," and Wide Open Throttle (WOT) conditions. The BARO reading displayed represents barometric pressure and is used to compensate for altitude differences.
THROT POSITION: Range 0-5 Volts
Used by the PCM to determine the amount of throttle demanded by the driver. The display should read 0.36-0.96 volt at idle to greater than 4 volts at wide open throttle.
THROTTLE ANGLE: Range 0-100%
Computed by the PCM from Throttle Position (TP) sensor voltage and should display 0% at idle and 100% at wide open throttle. Refer to DTC 21 if TP sensor angle is not 0% at idle.
HEATED OXYGEN SENSORS: (BANK 1 AND 2) Range 0-1132 mV
Represents the exhaust oxygen sensor output voltage. Should fluctuate constantly within a range between 10 mV (lean exhaust) and 1000 mV (rich exhaust) when operating in "Closed Loop."
LOOP STATUS: Scan tool displays OPEN or CLOSED
"Closed Loop" displayed indicates that the PCM is controlling fuel delivery according to oxygen sensor voltage. In "Open Loop," the PCM ignores the oxygen sensor voltage and bases the amount of fuel to be delivered on TP sensor, engine coolant, and MAP sensor inputs only.
SHORT TERM FUEL TRIM: Range 0-255 Counts
Short term fuel trim represents a short-term correction to fuel delivery by the PCM in response to the amount of time the oxygen sensor voltage spends above or below the 450 mV threshold. If the oxygen sensor voltage has mainly remained less than 450 mV, indicating a lean air/fuel mixture, short term fuel trim will increase and the PCM will add fuel. If the oxygen sensor voltage stays mainly above the threshold, the PCM will reduce fuel delivery to compensate for the indicated rich condition.
LONG TERM FUEL TRIM: Range 0-255 Counts
Long term fuel trim is derived from the short term fuel trim value and is used for long-term correction of fuel delivery A value of 128 counts indicates that fuel delivery requires no compensation to maintain a 14.7:1 air/fuel ratio. A value less than 128 counts indicates that the fuel system is rich and fuel delivery is being reduced (decreased injector pulse width).
A value greater than 128 counts indicates that a lean condition exists and the PCM is compensating by adding fuel (increased injector pulse width).
FUEL TRIM CELL: Range 0-255
Fuel trim cell is dependent upon engine speed and MAP sensor readings. Fuel trim cell indicates which cell is currently active.
FUEL TRIM ENABLE: Scan tool displays YES/NO
If the Fuel Trim Enable system is learning "YES" the long term fuel trim is responding to the short term fuel trim. If the Fuel Trim Enable indicates "NO" then long term fuel trim will not respond to changes in short term fuel trim.
SPARK ADVANCE: Scan tool range 0°-255°
This is a display of the spark advance Ignition Circuit (IC) calculation which the PCM calculates and then provides all spark advance to the ignition system. The PCM computes the desired spark advance using data such as engine coolant temperature, RPM, load, vehicle speed, and operating mode. There is no adjustment for spark advance.
MASS AIR FLOW: Scan tool range 0-512 Grams Per Second (GPS)
The PCM converts the mass air flow sensor input signal into grams per second, indicating the amount of air flow entering the engine.
KNOCK RETARD: Range 0° to 128°
Indicates the amount of spark advance the PCM is removing from IC in response to the Knock Sensor (KS) signal.
KNOCK SIGNAL: Scan tool displays YES/NO
Indicates whether or not a knock signal is being detected by the PCM. Should display "NO" at idle.
LO RESOLUTION SIGNAL: Range 0-1000 m/sec
This signal is generated by the ignition control module and should display time between low resolution signal reference pulses detected by the PCM.
HI RESOLUTION SIGNAL: Scan tool displays YES/NO
This signal is generated by the ignition control module and will switch from "NO" to "YES" when the PCM detects a high resolution signal.
INJECTOR PULSE WIDTH: Scan tool range 0.0-1000 m/sec
Indicates the time the injectors remain "ON." When engine load is increased, injector pulse width will increase.
IDLE AIR CONTROL: Range 0-255
Displays the commanded position of the Idle Air Control (IAC) pintle in counts. The greater the number of counts, the greater the idle air passages opened. Idle air control should respond fairly quickly to changes in engine load to maintain desired idle RPM.
LEARNED IAC: Range 0-255 counts
Learned IAC is an internal PCM parameter. Each time the vehicle is driven the IAC system learns how many counts is required to produce a given desired idle.
EGR DUTY CYCLE: Range 0-100%
The PCM cycles the Exhaust Gas Recirculation (EGR) solenoid valve "ON" and "OFF." The "ON" time (duty cycle) of the EGR solenoid valve, expressed as a percent, determines how much the exhaust gas is recirculated.
SYSTEM VOLTAGE: Range 0.0-25.5 Volts
This represents the system voltage measured by the PCM.
AIR CONTROL: Scan tool displays ON/OFF
When the PCM enables the Secondary Air Injection System, the scan tool will display Air Control "ON." When the PCM determines that AIR Control is not required the scan tool will display "OFF."
FUEL EVAP PURGE: Scan tool range 0-100%
Used to control EVAP canister purge function. 0% indicates the valve is commanded fully closed while 100% indicates that the valve is fully open.
INJECTOR FAULT: Scan tool displays YES/NO
"YES" indicates that the PCM does not detect voltage at the injector driver. Injector faults should indicate "NO," when circuits are OK.
TCS/ASR ACTIVE: Scan tool displays NO/YES
When the Acceleration Slip Regulation (ASR) system is active, the scan tool will display "YES."
FAN CONTROL PCM A10: Scan tool displays OFF/ON
- Early Production Vehicles: This will display "ON" when the PCM enables the secondary cooling fan.
- Late Production Vehicles: This will display "ON" when the PCM enables high speed fans.
FAN CONTROL PCM All: Scan tool displays OFF/ON
- Early Production Vehicles: This will display "ON" when the PCM enables the primary cooling fan.
- Late Production Vehicles: This will display "ON" when the PCM enables low speed fans, and when the PCM enables high speed fans.
A/C REQUEST: Scan tool displays YES/NO
Represents if the A/C request from the control head is being received by the PCM.
A/C CLUTCH: Scan tool displays ON/OFF
Represents the command state of the A/C clutch control relay. Clutch should be engaged when "ON" is displayed.
A/C STATUS: Scan tool displays ON/OFF
The scan tool will display "ON" if voltage has been applied to the A/C compressor clutch.
A/C REFRIG PRESSURE: Range 0-459 psi / 0.00-5.0 Volts
The scan tool displays the A/C refrigerant pressure used by the PCM for cooling fan operation and A/C diagnostic trouble codes.
A/C EVAP TEMP: -7°C to 32°C, 19°F to 90°F
The scan tool will display the A/C evaporator temperature and is used by the PCM to cycle the A/C clutch. The evaporator temperature sensor will also prevent evaporator freeze-up.
SKIP SHIFT ACT: Scan tool displays NO/YES
When the PCM enables the skip shift system, the scan tool will display "YES."
VEHICLE SPEED- Range 0-255 km/h, mph
The vehicle speed sensor signal is converted into km/h and mph for display.
TRANS RANGE SWITCH: Scan tool displays Park/Neutral, Reverse, Drive 4, Drive 3, Drive 2, Low and Invalid
These values represent the decoded sequence of the Transmission Range (TR) pressure switch assembly circuits and are used to determine manual valve position.
PARK/NEUTRAL POS: Scan tool displays - P-N-- or -R-DL
P-N-- displayed indicates that the gear select lever is in park or neutral.
TCC BRAKE SWITCH: Scan tool displays OPEN/CLOSED
When the brake pedal is applied, the switch sends a signal to the PCM to disengage the Torque Converter Clutch (TCC)solenoid.
TCC SOLENOID: Scan tool displays OFF/ON
The scan tool only indicates when PCM has enabled the TCC Driver, but this does not confirm that the TCC has engaged. To determine if TCC is operating properly, engine RPM should decrease when TCC is enabled.
1-2 SHIFT SOL: Scan tool displays ON/OFF
When the transmission is in first or fourth gear, the scan tool should display "ON." When the transmission is in second or third gear, the scan tool should indicate "OFF.".
2-3 SHIFT SOL: Scan tool displays ON/OFF
When the automatic transmission is in first or second gear, the scan tool should indicate "ON." When the transmission is in third or forth gear, the scan tool should display "OFF."
A/B/C RANGE (RNG): Scan tool displays ON/OFF, ON/OFF, ON/OFF
These parameters are the three inputs from the transmission range pressure switch assembly. "ON" represents a Battery Positive voltage signal, "OFF" represents a 0 voltage signal.
PERF MODE SWITCH: Scan tool displays OPEN/CLOSED
This parameter indicates the position of the performance mode switch. The scan tool will display "YES" when the switch is depressed and then "NO" when the switch is released.
ENG/TRANS DTC Detected: Scan tool displays YES/NO
This will display "YES" if the PCM detects a fault in an engine or transmission circuit that caused a Diagnostic Trouble Code (DTC).
KNOCK SENSOR: Scan tool displays 0K/Open/Grounded
The PCM monitors the KS circuit and can determine if the sensor is open, grounded, or if the circuit is "OK."
TIME FROM START: Range 0:00:00-18:12:15 HR/MIN/SEC
A measure of how long the engine has been operating. When the ignition is cycled to "OFF" the value is reset to zero.