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 High Side Pressure--Range 0-5.0 Volts: The A/C High Side displays the pressure value of the A/C refrigerant
pressure sensor. The A/C High Side helps diagnose the DTC P0530.
A/C High Side Pressure--Range 0-459 PSI: The A/C High Side displays the pressure value of the A/C refrigerant
pressure sensor. The A/C High Side helps diagnose the DTC P0530.
A/C Relay Command--Range ON/OFF: 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: Represents whether air conditioning (A/C) is being requested from
the HVAC selector. The input is received by the instrument panel cluster (IPC)
and then sent over Class II serial data to the PCM and finally to the
scan tool over Class II serial data.
Air Flow Calculated--Range 0-512 grams/second: The calculated air flow is a calculation based on manifold absolute
pressure. 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 PCM uses the fuel trim to adjust fueling
in order to maintain near an air fuel ratio of 14.7:1.
AIR Pump Relay Command--Range ON/OFF: Represents the commanded state of the AIR Pump Relay . The AIR
Pump should be engaged when the scan tool displays ON.
BARO--Range 11-105 kPa, 0-5.0 Volts: The powertrain control module (PCM) receives a barometric pressure
(BARO) value from the manifold absolute pressure (MAP) sensor. The PCM receives
this BARO value when the ignition is turned ON before the engine is started,
and the value is also updated at wide open throttle (WOT). The BARO value
is used to properly fuel the engine at deferent altitudes and barometric pressures.
CKP Active Counter (7X Reference)-- Range 0-255 Counts: The crankshaft position (CKP) activity counter displays whether
the PCM is receiving the 7X sync pulses from the ignition module. Helpful
in diagnosing DTC P0336 and Cranks But Will Not Run conditions.
CMP Active Counter--Range 0-255 Counts: The camshaft position (CMP) activity counter displays the activity
sent to the PCM from the CMP sensor. The counter will continually increment
while the engine is running. The CMP Act. Counter is helpful in
diagnosing the DTC P0340.
CMP Resync Counter--Range 0-255 Counts: The camshaft position (CMP) resync counter displays the number
of times the PCM had to resync with the CMP sensor. The CMP Resync Counter
is helpful in diagnosing the DTC P0341.
Cruise Control Active--Range Yes/No: Cruise Control Active is an input from the cruise control module
to the PCM and indicates if the cruise control system is in control of vehicle
speed. The PCM uses this information to change transmission shift
calibrations and to turn ON an indicator lamp on the instrument
panel cluster (IPC) (when equipped).
Cruise Release Clutch / TCC Pedal Switch--Range Applied/Unapplied: When the brake pedal is applied, the torque converter clutch (TCC)
brake switch sends a signal to the PCM to disengage the TCC and disable cruise
control.
Current Gear--Range 1-6: The scan tool displays the position of the transmission range switch
PRNDL inputs. This information is then sent by Class II serial data to
the instrument panel cluster (IPC) to be displayed to the operator
on the IPC. If a valid combination of inputs is not seen by the PCM,
Invalid will be displayed.
Cycles of Misfire Data--Range 0-99 Counts: Indicates the number of current misfire cycles that are present
in the engine. Increments only when misfires are current.
Desired Idle Speed-- 0-3187 RPM: The PCM commands the idle speed. The PCM compensates for various
engine loads in order to maintain the desired idle speed. The actual engine
RPMs speed should remain close to the desired idle under the various
engine loads with the engine idling.
ECT--Range -40°C to151°C (-40°F to 304°F): The engine coolant temperature (ECT) sensor sends engine temperature
information to the PCM. The PCM supplies 5 volts to the engine coolant
temperature 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 voltage
which is interpreted 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.
Engine LOAD--Range 0-100 percent: Indicates engine load based on manifold absolute pressure. The
higher the percentage, the more load the engine is under.
Engine Oil Life Remaining--Range 0-100 percent: Indicates engine oil life remaining before the next oil change.
The lower the percentage, the sooner the next oil change will be.
Engine Oil Pressure Switch--Range Low/OK: Indicates the amount of oil pressure being created by the engine.
LOW indicates oil pressure below manufacture specifications.
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 0-16384 RPM: Engine Speed is computed by the PCM 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 Purge Solenoid Command--Range 0-100 percent: Indicates the PCM command of the evaporative emission (EVAP) purge
valve solenoid in order to control the evaporative emission canister purge
function. At 0 percent the valve is commanded fully closed. 100 percent
implies that the valve is fully open.
Evap Test Results-- Range Passed/No Result: Indicates if the EVAP test has run and passed.
EVAP Test Abort Reason-- Range Abborted/Not Abborted: Indicates if the vechicle is outside the running conditions too
run the EVAP test and was abborted.
EVAP Test Status-- Range Test Completed/Test Running: Indicates the status of the EVAP test when applied.
EVAP Vent Solenoid Command-- Range Venting/Non-venting: Indicates the PCM command of the 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 Alcohol Content--Range 0-85 Percent: The alcohol content is a measurement of percentage of alcohol based
on the Hertz frequency output of the fuel composition sensor.
Fuel Composition Sensor--Range 0-60 milliseconds: The fuel composition sensor on time is a pulse width signal relating
to the temperature of the fuel. The ON time may range from 1 millisecond representing
-40 degrees C, and 5 milliseconds representing 125 degrees C.
Fuel Composition Sensor--Range 0-255 Hz.: The fuel composition sensor measures the fuel capacitance, temperature,
and fuel conductance to determine the amount of alcohol contained in a given
fuel. The actual output from the sensor is a Hertz frequency.
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 Pump Relay Command-- Range ON/OFF: Indicates the PCM command of the fuel pump relay.
Fuel Tank Pressure Sensor-- Range -25.89 to 32.45 mm hg: The fuel tank pressure 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 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 to 1.7 volts.
Fuel Temperature Sensor: The fuel temperature is a measurement in degrees of C or F based
on the fuel composition sensors pulse width output.
Fuel Trim Cell--Range 0-22: A fuel trim cell depends upon the engine speed and the 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 PCM is allowing
the generator to operate. The PCM can disable the generator under certain
conditions to ease starting. Inactive indicates that the PCM is
allowing generator operation, while active indicates that the
PCM is not allowing generator operation.
Generator G Terminal Signal--Range 0-100 %: Indicates the amount of ON time the PCM is commanding the generator.
HO2S 2-- Range 0-1132 mV: The rear heated oxygen sensor (HO2S 2) represents the exhaust oxygen
output voltage past the catalytic converter. This voltage remains inactive,
or the voltage will appear lazy within a range of 100 mV
(lean exhaust) and 900 mV (rich exhaust) when the system
is operating in a Closed Loop.
IAC Position--Range 0-255 Counts: The idle air control (IAC) pintle position command from the PCM
is displayed in counts. The higher the counts read, the more the commanded
idle speed is. The idle air control responds fairly quickly to
changes in the engine load in order to maintain the desired idle
RPM.
IAT Sensor--Range -40°C to 151°C (-40°F
to 304°F): The PCM converts the resistance of the intake air temperature (IAT)
sensor to degrees in the same manner as the ECT sensor. Intake air temp is
used by the PCM to adjust fuel delivery and spark timing according
to incoming air density.
Ignition 1 Signal--Range 0-25.5 volts: The ignition volts represents the system voltage measured by the
PCM at the ignition feed circuit.
Injector PWM -- Range 0-999.9 mS: Indicates the base pulse width modulation (PWM) or ON time of the
fuel injectors in milliseconds. When the engine load is increased,
the injector pulse width will increase.
Injector 1-4 Command-- Range 0-999.9 mS: Indicates the PCM command on the fuel injectors. The higher the
number the longer the PCM is commanding the fuel injectors ON.
Knock Retard--Range 0-90 degrees: The Adaptive Knock Retard indicates the long term amount of the
spark advance the PCM removes from the ignition control (IC). The PCM responds
to the knock sensor (KS) signal.
Long Term FT--Range 0-255 (-100 to 100 percent): The Long Term FT is derived from the Short Term FT value. The
Long Term FT is used for the long term correction of the fuel delivery.
A value of the 128 counts (0 percent) indicates that
the fuel delivery requires no compensation in order to maintain
a 14.7:1 air to fuel ratio. A value below 128 counts means
that the fuel system is too rich and the fuel delivery is being
reduced. The PCM is decreasing the injector pulse width. A value
above 128 counts indicates that a lean condition exists
for which the PCM is compensating.
Loop Status--Range Open/Closed: A Closed Loop displayed indicates that the PCM is controlling the
fuel delivery according to the oxygen sensor (O2S 1) voltage. The PCM controls
the fuel delivery air to fuel ratio as close to 14.7:1 as possible.
MAP Sensor--Range 11-105 kPa, 0-5.0 Volts: The manifold absolute pressure (MAP) sensor measures the change
in the intake manifold pressure which results from engine load and speed changes.
As the intake manifold pressure increases, the air density in
the intake also increases and additional fuel is required.
MIL Command--Range ON/OFF: Indicates whether the PCM is commanding the MIL ON or OFF.
Misfire Current #1-4--Range 0-255 Counts: Indicates the number of current misfires that are present in the
indicated cylinder. Increments only when misfire is current.
Misfire History #1-4--Range 0-255 Counts: Indicates the number of misfires that have occurred after 195 current
misfires have been counted. The current misfire counter will add the misfires
to the history misfire counter after 195 total misfires have taken
place. If 1 cylinder is misfiring, the misfiring current counter
will have 195 misfires counted before adding to its history counter.
If 2 cylinders are misfiring, the misfiring current counters will
add to their history counters after 97 misfires. Increments only
after a misfire DTC has been set.
Med. Resolution Resync Counter--Range 0-255 Counts: The medium resolution resync counter displays the number of times
the PCM had to resync the crankshaft position (CKP) sensor. The med. resolution
resync counter is helpful in diagnosing the DTC P0335.
Number of DTCs--Range 0-255: The number of current DTCs indicates the total number of current
diagnostic trouble codes (DTCs) set. These current DTCs set does not necessarily
mean that the malfunction indicator lamp (MIL) is illuminated.
O2S 1--Range 0-1132 mV: The oxygen sensor (O2S 1) reading represents the exhaust oxygen
sensor output voltage. This voltage will fluctuate constantly between 100 mV
(lean exhaust) to 900 mV (rich exhaust) when operating
in a Closed Loop.
Power Enrichment--Range Active/Inactive: The scan tool indicates when power enrichment mode is active (moderate
to heavy acceleration). Helpful in diagnosing DTC P1171.
Short Term FT--Range 0-255 (-100 to 100 percent): Short Term FT 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 has mainly been below 450 mV, indicating a lean air/fuel
mixture, Short Term FT will increase to tell the PCM to 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.
Spark--Range 64 to -64 degrees: This is a display of the spark advance (IC) calculation which the
PCM is programming in the ignition system. The desired spark advance is computed
using data such as engine temperature, RPM, engine load, vehicle
speed and operating mode.
Start Up ECT: Indicates the engine coolant temperature at engine start up.
TCC Enable Solenoid Command--Range Off/On: Indicates the PCM command on the TCC Enable Solenoid. TCC Enable
is determined by engine load, TPS, and MPH.
TP Sensor--Range 0-100 percent: The PCM computes the throttle position (TP) from the TP sensor
voltage input. The TP angle will auto zero to 0 percent at idle when
the TP voltage is below 0.90 volt. The TP angle will read
100 percent at wide open throttle (WOT).
TP Sensor--Range 0.0-0.5 Volts: The PCM uses the throttle position (TP) sensor to determine the
amount of the throttle demanded by the operator of the vehicle. The TP sensor
reads between 0.36-0.96 volt at idle to above 4.0 volts
at wide open throttle (WOT).
TR Switch--Range High or Low: A transaxle mounted switch is used as an input to let the PCM know
what position the gear select lever is in. The scan tool status will switch
from High to Low as different combinations are met. In Park, PRNDL
P and A will be Low and B and C will be High.
TWC Temperature Calculated: Represents the calculated temperature of the catalytic converter.
Useful for determining if the Catalyst Monitor Test has run.
Vehicle Speed Sensor--Range 0-255 MPH, 0-255 km/h: The vehicle speed sensor signal is converted into MPH/km/h for
display. The vehicle speed output from the PCM is 4000 pulses per mile.
The scan tool uses the Class 2 serial data from the PCM to obtain
vehicle speed, while the instrument panel cluster, cruise control
module and multi-function alarm module use the 4000 ppm
output.
VTD Fuel Disable--Range Active/Inactive: Indicates if the VTD module has received proper information to
enable or disable fuel.
VID Auto. Learn Timer--Range Active/Inactive: The Theft System Learn Mode is used to indicate when the PCM is
ready to learn the password during the Password Learn Procedure. More information
is located in the Password Learn Procedure portion of the service manual.