1998 OPEL FRONTERA sensor

6E–40
ENGINE DRIVEABILITY AND EMISSIONS
Common OBD Terms
Diagnostic
When used as a noun, the word diagnostic refers to any
on-board test run by the vehicle’s Diagnostic
Management System. A diagnostic is simply a test run on
a system or component to determine if the system or
component is operating according to specification. There
are many diagnostics, shown in the following list:
Oxygen sensors
Oxygen sensor heaters
EGR
Catalyst monitoring
Enable Criteria
The term “enable criteria” is engineering language for the
conditions necessary for a given diagnostic test to run.
Each diagnostic has a specific list of conditions which
must be met before the diagnostic will run. “Enable
criteria” is another way of saying “conditions required”.
The enable criteria for each diagnostic is listed on the first
page of the DTC description under the heading
“Conditions for Setting the DTC”. Enable criteria varies
with each diagnostic, and typically includes, but is not
limited to the following items:
engine speed
vehicle speed
ECT
MAF/MAP
barometric pressure
IAT
TP
fuel trim
TCC enabled
A/C on
Tr i p
Technically, a trip is a key on-run-key off cycle in which all
the enable criteria for a given diagnostic are met, allowing
the diagnostic to run. Unfortunately, this concept is not
quite that simple. A trip is official when all the enable
criteria for a given diagnostic are met. But because the
enable criteria vary from one diagnostic to another, the
definition of trip varies as well. Some diagnostic are run
when the vehicle is at operating temperature, some when
the vehicle first start up; some require that the vehicle be
cruising at a steady highway speed, some run only when
the vehicle is idle; some diagnostics function with the
TCC disables. Some run only immediately following a
cold engine start-up.
A trip then, is defined as a key on-run-key off cycle in
which the vehicle was operated in such a way as to satisfy
the enables criteria for a given diagnostic, and this
diagnostic will consider this cycle to be one trip. However,
another diagnostic with a different set of enable criteria
(which were not met) during this driving event, would not
consider it a trip. No trip will occur for that particular
diagnostic until the vehicle is driven in such a way as to
meet all the enable criteria.
The Diagnostic Executive
The Diagnostic Executive is a unique segment of
software which is designed to coordinate and prioritize
the diagnostic procedures as well as define the protocol
for recording and displaying their results. The main
responsibilities of the Diagnostic Executive are listed as
following:
Commanding the MIL (“Check Engine” lamp) on and
off
DTC logging and clearing
Freeze Frame data for the first emission related DTC
recorded
Non-emission related Service Lamp (future)
Operating conditions Failure Records buffer, (the
number of records will vary)
Current status information on each diagnostic
The Diagnostic Executive records DTCs and turns on the
MIL when emission-related faults occur. It can also turn
off the MIL if the conditions cease which caused the DTC
to set.
Diagnostic Information
The diagnostic charts and functional checks are designed
to locate a faulty circuit or component through a process
of logical decisions. The charts are prepared with the
requirement that the vehicle functioned correctly at the
time of assembly and that there are not multiple faults
present.
There is a continuous self-diagnosis on certain control
functions. This diagnostic capability is complemented by
the diagnostic procedures contained in this manual. The
language of communicating the source of the malfunction
is a system of diagnostic trouble codes. When a
malfunction is detected by the control module, a
diagnostic trouble code is set and the Malfunction
Indicator Lamp (MIL) (“Check Engine” lamp) is
illuminated.
Malfunction Indicator Lamp (MIL)
The Malfunction Indicator Lamp (MIL) looks the same as
the MIL you are already familiar with (“Check Engine”
lamp). However, OBD requires that the it illuminate under
a strict set of guide lines.
Basically, the MIL is turned on when the PCM detects a
DTC that will impact the vehicle emissions.
The MIL is under the control of the Diagnostic Executive.
The MIL will be turned on if an emissions-related
diagnostic test indicates a malfunction has occurred. It
will stay on until the system or component passes the
same test, for three consecutive trips, with no
emissionsrelated faults.
Extinguishing the MIL
When the MIL is on, the Diagnostic Executive will turn off
the MIL after
three consecutive trips that a “test passed”
has been reported for the diagnostic test that originally
caused the MIL to illuminate.
Although the MIL has been turned off, the DTC will remain
in the PCM memory (both Freeze Frame and Failure
Records) until
forty(40) warm-up cycles after no faults
have been completed.

6E–50
ENGINE DRIVEABILITY AND EMISSIONS
Primary System-Based Diagnostic
Primary System-Based Diagnostic
There are primary system-based diagnostics which
evaluate system operation and its effect on vehicle
emissions. The primary system-based diagnostics are
listed below with a brief description of the diagnostic
function:
Oxygen Sensor Diagnosis
The fuel control heated oxygen sensors (Bank 1 HO2S 1
and Bank 2 HO2S 1) are diagnosed for the following
conditions:
Inactive signal (output steady at bias voltage – approx.
450 mV)
Signal fixed high
Signal fixed low
If the oxygen sensor pigtail wiring, connector or terminal
are damaged, the entire oxygen sensor assembly must
be replaced. DO NOT attempt to repair the wiring,
connector or terminals. In order for the sensor to function
properly, it must have clean reference air provided to it.
This clean air reference is obtained by way of the oxygen
sensor wire(s). Any attempt to repair the wires, connector
or terminals could result in the obstruction of the
reference air and degrade oxygen sensor performance.
Refer to
On-Vehicle Service, Heated Oxygen Sensors.
Fuel Control Heated Oxygen Sensor
The main function of the fuel control heated oxygen
sensors is to provide the control module with exhaust
stream oxygen content information to allow proper fueling
and maintain emissions within mandated levels. After it
reaches operating temperature, the sensor will generate
a voltage, inversely proportional to the amount of oxygen
present in the exhaust gases. The control module uses
the signal voltage from the fuel control heated oxygen
sensors while in closed loop to adjust fuel injector pulse
width. While in closed loop, the PCM can adjust fuel
delivery to maintain an air/fuel ratio which allows the best
combination of emission control and driveability.
HO2S Heater
Heated oxygen sensors are used to minimize the amount
of time required for closed loop fuel control to begin
operation and to allow accurate catalyst monitoring. The
oxygen sensor heater greatly decreases the amount of
time required for fuel control sensors (Bank 1 HO2S 1 and
Bank2 HO2S 1) to become active. Oxygen sensor
heaters are required to maintain a sufficiently high
temperature which allows accurate exhaust oxygen
content readings further away from the engine.
Fuel Trim System Monitor Diagnostic
Operation
Fuel Trim System Monitor Diagnostic
Operation
This system monitors the averages of short-term and
long-term fuel trim values. If these fuel trim values stay at
their limits for a calibrated period of time, a malfunction is
indicated. The fuel trim diagnostic compares the
averages of short-term fuel trim values and long-term fuel
trim values to rich and lean thresholds. If either value is
within the thresholds, a pass is recorded. If both values
are outside their thresholds, a rich or lean DTC will be
recorded.
The fuel trim system diagnostic also conducts an intrusive
test. This test determines if a rich condition is being
caused by excessive fuel vapor from the EVAP canister.
In order to meet OBD requirements, the control module
uses weighted fuel trim cells to determine the need to set
a fuel trim DTC. A fuel trim DTC can only be set if fuel trim
counts in the weighted fuel trim cells exceed
specifications. This means that the vehicle could have a
fuel trim problem which is causing a problem under
certain conditions (i.e., engine idle high due to a small
vacuum leak or rough idle due to a large vacuum leak)
while it operates fine at other times. No fuel trim DTC
would set (although an engine idle speed DTC or HO2S
DTC may set). Use a Tech 2 to observe fuel trim counts
while the problem is occurring.
A fuel trim DTC may be triggered by a number of vehicle
faults. Make use of all information available (other DTCs
stored, rich or lean condition, etc.) when diagnosing a fuel
trim fault.
Fuel Trim Cell Diagnostic Weights
N o f u e l t r i m D T C w i l l s e t r e g a r d l e s s o f t h e f u e l t r i m c o u n t s
in cell 0 unless the fuel trim counts in the weighted cells
are also outside specifications. This means that the
vehicle could have a fuel trim problem which is causing a
problem under certain conditions (i.e. engine idle high due
to a small vacuum leak or rough due to a large vacuum
leak) while it operates fine at other times. No fuel trim
DTC would set (although an engine idle speed DTC or
HO2S DTC may set). Use a Tech 2 to observe fuel trim
counts while the problem is occurring.

6E–53 ENGINE DRIVEABILITY AND EMISSIONS
On-Board Diagnostic (OBD) System Check
StepActionVa l u e ( s )Ye sNo
11. Ignition “ON,” engine “OFF.”
2. Observe the malfunction indicator lamp (MIL or
“Check Engine” lamp).
Is the MIL (“Check Engine” lamp)“ON?”
—Go to Step 2
Go to No MIL
(“Check
Engine” lamp)
21. Ignition “OFF.”
2. Install a Tech 2.
3. Ignition “ON.”
4. Attempt to display PCM engine data with the Tech 2.
Does the Tech 2 display PCM data?
—Go to Step 3Go to Step 8
31. Using the Tech 2 output tests function, select MIL
(“Check Engine” lamp) dash lamp control and
command the MIL (“Check Engine” lamp) “OFF.”
2. Observe the MIL (“Check Engine” lamp).
Did the MIL (“Check Engine” lamp) turn “OFF?”
—Go to Step 4
Go to MIL
(“Check
Engine” lamp)
On Steady
4Attempt to start the engine.
Did the engine start and continue to run?
—Go to Step 5
Go to Cranks
But Will Not
Run
5Select “Display DTCs” with the Tech 2.
Are any DTCs stored?
—Go to Step 6Go to Step 7
6Are two or more of the following DTCs stored? P0107,
P0108, P0113, P0118, P0122, P0123, P0712.?
—
Go to
“Multiple
PCM
Information
Sensor DTCs
Set”
Go to
applicable
DTC table
7Compare PCM data values displayed on the Tech 2 to
the typical engine scan data values.
Are the displayed values normal or close to the typical
values?
—
Refer
to
Ty p i c a l
scan data
value
Refer to
indicated
Component
System
Checks
81. Ignition “OFF,” disconnect the PCM.
2. Ignition “ON,” engine “OFF.”
3. Check the Class 2 data circuit for an open, short to
ground, or short to voltage. Also, check the DLC
ignition feed circuit for an open or short to ground
and the DLC ground circuit for an open.
4. If a problem is found, repair as necessary.
Was a problem found?
—Go to Step 2Go to Step 9
9Attempt to display PCM data with the Tech 2.
Does the Tech 2 display PCM engine data?
—Go to Step 2Go to Step 10
10Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
Powertrain Control Module
(PCM) in On-Vehicle Service.
Is the action complete?—Go to Step 2—

6E–65 ENGINE DRIVEABILITY AND EMISSIONS
Knock Sensor Diagnosis
The Tech 2 has two data displays available for diagnosing
the knock sensor (KS) system. The two displays are
described as follows:
“Knock Retard” indicates the number of degrees that
the spark timing is being retarded due to a knock
condition.
“KS Noise Channel” indicates the current voltage level
being monitored on the noise channel.
DTCs P0325 and P0327 are designed to diagnose the KS
module, the knock sensor, and the related wiring. The
problems encountered with the KS system should set a
DTC. However, if no DTC was set but the KS system is
suspect because of a detonation complaint, refer to
Detonation/Spark Knock in Symptoms.
Powertrain Control Module (PCM)
Diagnosis
To read and clear diagnostic trouble codes, use a Tech 2.
IMPORTANT:Use of a Tech 2 is recommended to clear
diagnostic trouble codes from the PCM memory.
Diagnostic trouble codes can also be cleared by turning
the ignition “OFF” and disconnecting the battery power
from the PCM for 30 seconds. Turning off the ignition and
disconnecting the battery power from the PCM will cause
all diagnostic information in the PCM memory to be
cleared. Therefore, all the diagnostic tests will have to be
re-run.
Since the PCM can have a failure which may affect only
one circuit, following the diagnostic procedures in this
section will determine which circuit has a problem and
where it is.
If a diagnostic chart indicates that the PCM connections
or the PCM is the cause of a problem, and the PCM is
replaced, but this does not correct the problem, one of the
following may be the reason:
There is a problem with the PCM terminal connections.
The terminals may have to be removed from the
connector in order to check them properly.
The problem is intermittent. This means that the
problem is not present at the time the system is being
checked. In this case, refer to the
Symptoms p o r t i o n o f
the manual and make a careful physical inspection of
all component and wiring associated with the affected
system.
There is a shorted solenoid, relay coil, or harness.
S o l e n o i d s a n d r e l a y s a r e t u r n e d “ O N ” a n d “ O F F ” b y t h e
PCM using internal electronic switches called drivers.
A shorted solenoid, relay coil, or harness will not
damage the PCM but will cause the solenoid or relay to
be inoperative.
Multiple PCM Information Sensor
DTCS Set
Circuit Description
The powertrain control module (PCM) monitors various
sensors to determine the engine operating conditions.
The PCM controls fuel delivery, spark advance,
transmission operation, and emission control device
operation based on the sensor inputs.The PCM provides a sensor ground to all of the sensors.
The PCM applies 5 volts through a pull-up resistor, and
determines the status of the following sensors by
monitoring the voltage present between the 5-volt supply
and the resistor:
The engine coolant temperature (ETC) sensor
The intake air temperature (IAT) sensor
The transmission fluid temperature (TFT) sensor
The PCM provides the following sensors with a 5-volt
reference and a sensor ground signal:
The exhaust gas recirculating (EGR) pintle position
sensor
The throttle position (TP) sensor
The manifold absolute pressure (MAP) sensor
The PCM monitors the separate feedback signals from
these sensors in order to determine their operating
status.
Diagnostic Aids
IMPORTANT:Be sure to inspect PCM and engine
grounds for being secure and clean.
A short to voltage in one of the sensor input circuits may
cause one or more of the following DTCs to be set:
P0108
P0113
P0118
P0123
P0560
P0712
P0406
IMPORTANT:If a sensor input circuit has been shorted
to voltage, ensure that the sensor is not damaged. A
damaged sensor will continue to indicate a high or low
voltage after the affected circuit has been repaired. If the
sensor has been damaged, replace it.
An open in the sensor ground circuit between the PCM
and the splice will cause one or more of the following
DTCs to be set:
P0108
P0113
P0118
P0123
P0712
P0406
A short to ground in the 5-volt reference A or B circuit will
cause one or more of the following DTCs to be set:
P0107
P0122
In the 5-volt reference circuit A, between the PCM and the
splice, will cause one or more of the following DTCs to be
set:
P0122
In the 5-volt reference circuit B, between the PCM and the
splice, will cause one or more of the following DTCs to be
set:
P0107
Check for the following conditions:

6E–66
ENGINE DRIVEABILITY AND EMISSIONS
Poor connection at PCM. Inspect the harness
connectors for backed-out terminals, improper mating,
broken locks, improperly formed or damage terminals,
and a poor terminal-to-wire connection.
Damaged harness. Inspect the wiring harness for
damage. If the harness is not damaged, observe an
affected sensor’s displayed value on the Tech 2 with
the ignition “ON” and the engine “OFF” while you move
the connectors and the wiring harnesses related to the
following sensors:
IAT
ECT
TP
MAP
EGR
TFT
Multiple PCM Information Sensor DTCs Set
StepActionVa l u e ( s )Ye sNo
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2
Go to OBD
System
Check
21. Turn the ignition “OFF,” disconnect the PCM.
2. Turn the ignition “ON,” check the 5 volt reference A
circuit for the following conditions:
A poor connection at the PCM.
An open between the PCM connector and the
splice.
A short to ground.
A short to voltage.
Is there an open or short?
—Go to Step 3Go to Step 4
3Repair the open or short.
Is the action complete?
—Verify repair—
4Check the sensor ground circuit for the following
conditions:
A poor connection at the PCM or the affected
sensors.
An open between the PCM connector and the
affected sensors.
Is there an open or a poor connection?
—Go to Step 5Go to Step 6
5Repair the open or the poor connection.
Is the action complete?
—Verify repair—
6Measure the voltage between the EGR pintle position
sensor signal circuit at the PCM harness connector and
ground.
Does the voltage measure near the specified value?
0 VGo to Step 7Go to Step 12
7Measure the voltage between the MAP sensor signal
circuit at the PCM harness connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 8Go to Step 15
8Measure the voltage between the TP sensor signal
circuit at the PCM harness connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 9Go to Step 16
9Measure the voltage between the IAT sensor signal
circuit at the PCM harness connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 10Go to Step 17
10Measure the voltage between the ECT sensor signal
circuit at the PCM harness connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 11Go to Step 18

6E–67 ENGINE DRIVEABILITY AND EMISSIONS
Multiple PCM Information Sensor DTCs Set
StepNo Ye s Va l u e ( s ) Action
111. Disconnect the EGR valve.
2. Measure the voltage between the EGR pintle
position sensor signal circuit at the PCM harness
connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 13Go to Step 18
12Measure the voltage between the TFT sensor signal
circuit at the PCM harness connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 20Go to Step 19
13Replace the EGR valve.
Is the action complete?
—Verify repair—
14Locate and repair the short to voltage in the MAP
sensor signal circuit.
Is the action complete?
—Verify repair—
15Locate and repair the short to voltage in the TP sensor
signal circuit.
Is the action complete?
—Verify repair—
16Locate and repair the short to voltage in the IAT sensor
signal circuit.
Is the action complete?
—Verify repair—
17Locate and repair the short to voltage in the ECT
sensor signal circuit.
Is the action complete?
—Verify repair—
18Locate and repair the short to voltage in the EGR pintle
position sensor signal circuit.
Is the action complete?
—Verify repair—
19Locate and repair the short to voltage in the TFT sensor
signal circuit.
Is the action complete?
—Verify repair—
20Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—
Go to OBD
System
Check
—

6E–68
ENGINE DRIVEABILITY AND EMISSIONS
Exhaust Gas Recirculation (EGR)
Diagnosis (For except EXPORT and
SOUTH AFRICA)
Pintle position error diagnosis is covered by DTC P0402,
P0404, P1404, P0405, P0406. If EGR diagnostic trouble
codes P0402, P0404, P1404, P0405, P0406 are
encountered, refer to the DTC charts.
Engine Tech 2 Data Definitions and
Ranges
A/C CLUTCH – Tech 2 Displays ON or OFF –
Indicates whether the PCM 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 PCM 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 PCM 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.
BAROMETRIC PRESSURE — Tech 2 Range 10-105
kPa/0.00-5.00 Volts —
The barometric pressure reading is determined from the
MAP sensor signal monitored during key up and wide
open throttle (WOT) conditions. The barometric pressure
is used to compensate for altitude differences and is
normally displayed around “61-104” depending on
altitude and barometric pressure.
CHECK TRANS LAMP — AUTO TRANSMISSION —
Indicates the need to check for a DTC with the Tech 2
when the lamp is flashing 0.2 seconds ON and 0.2
seconds OFF.
CMP ACT. COUNTER – Cam Position Activity
DECEL FUEL MODE — Tech 2 Display ACTIVE or
INACTIVE —
“ACTIVE” displayed indicates that the PCM has detected
conditions appropriate to operate in deceleration fuel
mode. The PCM will command the deceleration fuel
mode when it detects a closed throttle position while the
vehicle is traveling over 20 mph. While in the deceleration
fuel delivered by entering open loop and decreasing the
injector pulse width.
DESIRED EGR POS. — Tech 2 Range 0%-100% —
Represents the EGR pintle position that the PCM is
commanding.
DESIRED IDLE — Tech 2 Range 0-3187 RPM —
The idle speed that the PCM is commanding. The PCM
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 151C (–40F to 304F) —
The engine coolant temperature (ECT) 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 (high resistance), the PCM
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 PCM will interpret
the lower voltage as a warm engine.
EGR DUTY CYCLE — Tech 2 Range 0%-100% —
Represents the EGR valve driver PWM signal from the
PCM. A duty cycle of 0% indicates that no EGR flow is
being commanded; a 100% duty cycle indicates
maximum EGR flow commanded.
EGR FEEDBACK — Tech 2 Range 0.00-5.00 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 retracted pintle (open valve).
ENGINE LOAD — Tech 2 Range 0%-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 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 PCM from the 58X
reference input. It should remain close to desired idle
under various engine loads with engine idling.
FUEL PUMP — Tech 2 Displays ON or OFF —
Indicates the PCM commanded state of the fuel pump
relay driver circuit.
FUEL TRIM CELL — Tech 2 Range 0-21 —
The fuel trim cell is dependent upon engine speed and
MAF sensor readings. A plot of RPM vs. MAF is divided
into 22 cells. Fuel trim cell indicates which cell is currently
active.
FUEL TRIM LEARN — Tech 2 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
the short term fuel trim. If the fuel trim learn displays
“NO,” then long term fuel trim will not respond to changes
in short term fuel trim.
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.

6E–69 ENGINE DRIVEABILITY AND EMISSIONS
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 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 PCM 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 PCM 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 2
SEN. 1 — 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 PCM
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 PCM will monitor the HO2S
voltage. When the HO2S voltage indicates a sufficiently
active sensor, the PCM looks at how much time has
elapsed since start-up. If the PCM determines that too
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”.
IAC POSITION — Tech 2 Range 0-255 Counts —
Displays the commanded position of the idle air control
pintle in counts. A larger number of counts means that
more air is being commanded through the idle air
passage. Idle air control should respond fairly quickly to
changes in engine load to maintain desired idle RPM.
IAT (INTAKE AIR TEMPERATURE) — Tech 2 Range
–40
C to 151C (–40F to 304F) —
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.
IGNITION 1 — Tech 2 Range 0-25.5 Volts —
This represents the system voltage measured by the
PCM at its ignition feed.
INJ. PULSE BANK 1/INJ. PULSE BANK 2 — Tech 2
Range 0-1000 msec. —
Indicates the amount of time the PCM 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.KS NOISE CHANNEL (Knock Sensor) —
Indicates the output from the KS noise channel. There is
always some electrical noise in an engine compartment
and to avoid mistaking this as engine knock, the output
from the knock sensor is compared to the output from the
noise channel. A knock condition is not set unless the
knock sensor output is greater than the noise channel
output.
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 PCM 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 PCM 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.
LOOP STATUS — Tech 2 Displays OPEN or
CLOSED —
“CLOSED” indicates that the PCM is controlling fuel
delivery according to oxygen sensor voltage. In “OPEN”
the PCM 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 gm/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.
MAP — Tech 2 Range 10-105 kPa (0.00-4.97 Volts)
—
The manifold absolute pressure (MAP) sensor measures
the change in the intake manifold pressure from engine
load, EGR flow, and speed changes. As intake manifold
pressure increases, intake vacuum decreases, resulting
in a higher MAP sensor voltage and kPa reading. The
MAP sensor signal is used to monitor intake manifold
pressure changes during the EGR flow test, to update the
BARO reading, and as an enabling factor for several of
the diagnostics.
MIL — Tech 2 Displays ON or OFF —
Indicates the PCM commanded state of the malfunction
indicator lamp.
POWER ENRICHMENT — Tech 2 Displays ACTIVE
or INACTIVE —
“ACTIVE” displayed indicates that the PCM has detected
conditions appropriate to operate in power enrichment
mode. The PCM will command power enrichment mode
when a large increase in throttle position and load is
detected. While in power enrichment mode, the PCM will
increase the amount of fuel delivered by entering open
loop and increasing the injector pulse width. This is done
to prevent a possible sag or hesitation from occurring
during acceleration.