2002 ISUZU AXIOM display

6E±58
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

For the 3.5L w/automatic transmission, the
pre-catalyst sensors are designated Bank 1 HO2S 1
and Bank 2 HO2S 1. The post-catalyst sensors are
Bank 1 HO2S 2 and Bank 2 HO2S 2.
Catalyst Monitor Outputs
The catalyst monitor diagnostic is sensitive to the
following conditions:

Exhaust leaks

HO2S contamination

Alternate fuels
Exhaust system leaks may cause the following:

Preventing a degraded catalyst from failing the
diagnostic.

Causing a false failure for a normally functioning
catalyst.

Preventing the diagnostic from running.
Some of the contaminants that may be encountered are
phosphorus, lead, silica, and sulfur. The presence of
these contaminants will prevent the TWC diagnostic from
functioning properly.
Three-Way Catalyst Oxygen Storage Capacity
The Three-Way catalyst (TWC) must be monitored for
efficiency. To accomplish this, the control module
monitors the pre-catalyst HO2S and post-catalyst HO2S
oxygen sensors. When the TWC is operating properly,
the post-catalyst oxygen sensor will have significantly
less activity than the pre-catalyst oxygen sensor. The
TWC stores and releases oxygen as needed during its
normal reduction and oxidation process. The control
module will calculate the oxygen storage capacity using
the difference between the pre-catalyst and post catalyst
oxygen sensor's voltage levels. If the activity of the
post-catalyst oxygen sensor approaches that of the
pre-catalyst oxygen sensor, the catalyst's efficiency is
degraded.
Stepped or staged testing level allow the control module
to statistically filter test information. This prevents falsely
passing or falsely failing the oxygen storage capacity test.
The calculations performed by the on-board diagnostic
system are very complex. For this reason, post catalyst
oxygen sensor activity should not be used to determine
oxygen storage capacity unless directed by the service
manual.
Two stages are used to monitor catalyst efficiency.
Failure of the first stage will indicate that the catalyst
requires further testing to determine catalyst efficiency.
The seconds stage then looks at the inputs for the pre and
post catalyst HO2S sensors more closely before
determining if the catalyst is indeed degraded. This
further statistical processing is done to increase the
accuracy of oxygen storage capacity type monitoring.
Failing the first (stage 1) test DOES NOT indicate a failed
catalyst. The catalyst may be marginal or the fuel sulfur
content could be very high.Aftermarket HO2S characteristics may be different from
the original equipment manufacturer sensor. This may
lead to a false pass or a false fail of the catalyst monitor
diagnostic. Similarly, if an aftermarket catalyst does not
contain the same amount of cerium as the original part,
the correlation between oxygen storage and conversion
efficiency may be altered enough to set a false DTC.
Misfire Monitor Diagnostic Operation
Misfire Monitor Diagnostic Operation
Misfire is monitored as a function of the combustion
quality (CQ) signals generated from the ignition current
sense system. Combustion signals represent the degree
of combustion in each cylinder. Misfire is detected when
the combustion signal is below a predetermined value.
The misfire ratio is calculated once every 100 engine
cycles. For example, on a 6-cylinder engine, 600 ignition
plug sparks occur every 100 cycles and if a misfire occurs
12 times during that time, the misfire is 12/600 y 100 = 2
%.
Misfire Counters
Whenever a cylinder misfires, the misfire diagnostic
counts the misfire and notes the crankshaft position at the
time the misfire occurred. These ªmisfire countersº are
basically a file on each engine cylinder. A current and a
history misfire counter are maintained for each cylinder.
The misfire current counters (Misfire Cur #1-6) indicate
the number of firing events out of the last 100 cylinder
firing events which were misfires. The misfire current
counter will display real time data without a misfire DTC
stored. The misfire history counters (Misfire Hist #1-6)
indicate the total number of cylinder firing events which
were misfires. The misfire history counters will display 0
until the misfire diagnostic has failed and a DTC P0300 is
set. Once the misfire DTC P0300 is set, the misfire
history counters will be updated every 100 cylinder firing
events. A misfire counter is maintained for each cylinder.
If the misfire diagnostic reports a failure, the diagnostic
executive reviews all of the misfire counters before
reporting DTC. This way, the diagnostic executive
reports the most current information.
When crankshaft rotation is erratic, a misfire condition will
be detected. Because of this erratic condition, the data
that is collected by the diagnostic can sometimes
incorrectly identify which cylinder is misfiring. Misfires are
counted from more than one cylinder. Cylinder #1 has the
majority of counted misfires. In this case, the Misfire
Counters would identify cylinder #1 as the misfiring
cylinder. The misfires in the other counters were just
background noise caused by the erratic misfire rotation of
the crankshaft. If the number of accumulated misfires is
sufficient for the diagnostic to identify a true misfire, the
diagnostic will set DTC P0300 ± Misfire Detected.
Use diagnostic equipment to monitor misfire counter data
on OBD II-compliant vehicles. Knowing which specific
cylinder(s) misfired can lead to the root cause, even when
dealing with a multiple cylinder misfire. Using the
information in the misfire counters, identify which
cylinders are misfiring. If the counter indicate cylinders

6E±61
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
On-Board Diagnostic (OBD II) System Check

StepActionValue(s)Ye sNo
11. Ignition ªONº, engine ªOFFº.
2. Observe the malfunction indicator lamp (MIL or
ªCheck Engine lampº).
Is the MIL (ªCheck Engine lampº)ªONº?
ÐGo to Step 2
Go to No
MIL(ªCheck
Engine lampº)
21. Ignition ªONº, engine ªOFFº.
2. Observe the ªReduced Power lampº.
Is the RPL (ªReduced Power lampº) ªONº?
ÐGo to Step 3
Go to No
RPL(ªReduce
d Power
lampº)
31. Ignition ªOFFº.
2. Install Tech 2.
3. Ignition ªONº.
4. Attempt to display PCM engine data with the
Tech 2.
Does the Tech 2 display PCM data?
ÐGo to Step 4Go to Step 12
41. Using the Tech 2 output tests function, select MIL
(ªCheck Engine lampº) control and command the
MIL (ªCheck Engine Lampº) ªOFFº.
2. Observe the MIL (ªCheck Engine lampº).
Did the MIL (ªCheck Engine lampº) turn ªOFFº?
ÐGo to Step 5
Go to
MIL(ªCheck
Engine lampº)
On Steady
51. Using the Tech 2 output tests function, select MIL
(ªCheck Engine lampº) control and command the
RPL (ªReduced Power lampº) ªOFFº.
2. Observe the RPL (ªReduced Power lampº).
Did the MIL (ªReduced Power lampº) turn ªOFFº?
ÐGo to Step 6
Go to
RPL(ªReduce
d Power
lampº) On
Steady
6Select ªDisplay DTCsº with the Tech 2.
Are any DTCs stored?
ÐGo to Step 7Go to Step 11
7Stored DTCs.
P0562, P0563, P0601, P0602, P0604, P0606, P1625,
P1635, P1639, P1640, P1650
Are the applicable DTCs stored?
Ð
Go to
applicable
DTC table
Go to Step 8
8Stored DTCs.
P1514, P1515, P1516, P1523, P1125, P1290, P1295,
P1299
Are the applicable DTCs stored?
Ð
Go to
applicable
DTC table
Go to Step 9
9Stored DTCs.
1. P0425, P0106, P0107, P1107, P0401, P1404,
P0405, P1120, P1221, P1515, P1516, P1275,
P1635, P1271, P1273, P1285, P1272
2. P0336, P0337, P1220, P1515, P1221, P1516,
P1280, P1639, P1271, P1272
Are the applicable DTCs stored?
Ð
Go to
ªMultiple
PCM
Information
sensor DTCs
Setº
Go to Step 10
10Attempt to crank the starter motor
Did the starter motor crank?
ÐGo to Step 10
Go to Starter
control
system
11Attempt to start the engine.
Did the engine start and continue to run?
ÐGo to Step 6
Go to Cranks
But Will Not
Run

6E±62
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
On-Board Diagnostic (OBD II) System Check

 
StepNo Ye s Value(s) Action
12Compare 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?
Ð
Go to
Symptom
Refer to
indicated
Component
System
Checks
131. Ignition ªOFFº, disconnect the PCM.
2. Ignition ªONº, engine ªOFFº.
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?
ÐGo to Step 2Go to Step 14
141. Attempt to reprogram the PCM. Refer to Powertrain
Control Module (PCM) in On-Vehicle Service.
2. Attempt to display PCM data with the Tech 2.
Does the Tech 2 display PCM engine data?
ÐGo to Step 2Go to Step 15
15Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
ON-Vehicle Service in Power
Control Module and Sensors for procedures.
And also refer to latest Service Bulletin. Check to see
if the latest software is released or not. And then Down
Load the LATEST PROGRAMMED SOFTWARE to the
replacement PCM.
Is the action complete?
ÐGo to Step 2Ð

6E±64
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Diagnosis
This chart should be used for diagnosing the electrical
portion of the A/C compressor clutch circuit. A Tech 2 will
be used in diagnosing the system. The Tech 2 has the
ability to read the A/C request input to the PCM. The
Tech 2 can display when the PCM has commanded the
A/C clutch ªONº. The Tech 2 should have the ability to
override the A/C request signal and energize the A/C
compressor relay.
Test Description
IMPORTANT:Do not engage the A/C compressor
clutch with the engine running if an A/C mode is not
selected at the A/C control switch.
The numbers below refer to the step numbers on the
Diagnostic Chart:3. This a test determine is the problem is with the
refrigerant system. If the switch is open, A/C
pressure gauges will be used to determine if the
pressure switch is faulty or if the system is partially
discharged or empty.
4. Although the normal complaint will be the A/C clutch
failing to engage, it is possible for a short circuit to
cause the clutch to run when A/C has not been
selected. This step is a test for that condition.
7. There is an extremely low probability that both relays
will fail at the same time, so the substitution process
is one way to check the A/C Thermostat relay. Use
a known good relay to do a substitution check.
A/C Clutch Control Circuit Diagnosis

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Are any other DTCs stored?
Ð
Go to the
other DTC
chart(s) first
Go to Step 3
31. Disconnect the electrical connector at the pressure
switch located on the receiver/drier.
2. Use an ohmmeter to check continuity across the
pressure switch.
Is the pressure switch open?
Ð
Go to Air
Conditioning
to diagnose
the cause of
the open
pressure
switch
Go to Step 4
4IMPORTANT:Before continuing with the diagnosis, the
following conditions must be met:

The intake air temperature must be greater than
15
C. (60
F).

The engine coolant temperature must be less
than 119
C (246
F).
1. A/C ªOFFº.
2. Start the engine and idle for 1 minute.
3. Observe the A/C compressor.
Is the A/C compressor clutch engaged even though
A/C has not been requested?
ÐGo to Step 37Go to Step 5
51. Idle the engine.
2. A/C ªONº.
3. Blower ªONº.
4. Observe the A/C compressor.
Is the A/C compressor magnetic clutch engaged?
Ð
Refer to
Diagnostic
Aids
Go to Step 6
61. Engine idling.
2. A/C ªONº.
3. Blower ªONº.
4. Observe the ªA/C Requestº display on the Tech 2.
(Refer to the Miscellaneous test)
Does the tool ªA/C Requestº display indicate ªYesº?
ÐGo to Step 26Go to Step 7

6E±65
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Control Circuit Diagnosis

 
StepNo Ye s Value(s) Action
7Temporarily substitute the A/C compressor relay in
place of the A/C thermostat relay, then repeat Step 5.
Did the ªA/C Requestº display indicate ªYesº?
ÐGo to Step 8Go to Step 9
8Replace the original A/C thermostat relay.
Is the action complete?
ÐVerify repairÐ
9Does the blower operate?ÐGo to Step 10Go to Step 11
10Repair the blower.
Is the action complete?
ÐVerify repairÐ
11Check for a faulty 10A A/C fuse in the underdash fuse
panel.
Was the 10A fuse OK?
ÐGo to Step 13Go to Step 12
12Check for short circuit and make repairs if necessary.
Replace the 10A A/C fuse.
Is the action complete?
ÐVerify repairÐ
131. Remove the glove box to gain access to the A/C
thermostat.
2. Disconnect the thermostat connector.
3. Attach a fused jumper between ground and the
thermostat wire.
4. A/C ªONº.
5. Blower ªONº.
Dose A/C request indicate ªYESº on the Tech 2?
ÐGo to Step 14Go to Step 17
141. Ignition ªONº.
2. Use a DVM to check voltage at the electronic A/C
thermostat.
Was voltage equal to the specified value?
B+Go to Step 17Go to Step 15
15Check for open wire between the thermostat and the
A/C switch.
Was the wire open?
ÐGo to Step 16Go to Step 17
16Repair the open wire between the thermostat and the
A/C switch.
Is the action complete?
ÐVerify repairÐ
17Check for an open circuit between A/C thermostat relay
and PCM A/C request terminal (F45).
Was there an open circuit?
ÐGo to Step 18Go to Step 19
18Repair the open circuit between the PCM and A/C
thermostat relay.
Is the action complete?
ÐVerify repairÐ
191. Ignition ªONº.
2. Use a DVM to check voltage at the A/C pressure
switch.
Was voltage equal to the specified value?
B+Go to Step 21Go to Step 20
20Repair the open circuit between the 10A A/C fuse and
the pressure switch.
Is the action complete?
ÐVerify repairÐ

6E±68
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Electronic Ignition System Diagnosis
If the engine cranks but will not run or immediately stalls,
the Engine Cranks But Will Not Start chart must be used
to determine if the failure is in the ignition system or the
fuel system. If DTC P0300 through P0306, P0341, or
P0336 is set, the appropriate diagnostic trouble code
chart must be used for diagnosis.
If a misfire is being experienced with no DTC set, refer to
the
Symptoms section for diagnosis.
EVAP Canister Purge Solenoid and
EVAP Vent Solenoid Valve
A continuous purge condition with no purge commanded
by the PCM will set a DTC P1441. Refer to the DTC charts
for further information.
Visual Check of The Evaporative
Emission Canister

If the canister is cracked or damaged, replace the
canister.

If fuel is leaking from the canister, replace the canister
and check hoses and hose routing.
Fuel Metering System Check
Some failures of the fuel metering system will result in an
ªEngine Cranks But Will Not Runº symptom. If this
condition exists, refer to the
Cranks But Will Not Run
chart. This chart will determine if the problem is caused
by the ignition system, the PCM, or the fuel pump
electrical circuit.
Refer to
Fuel System Electrical Test for the fuel system
wiring schematic.
If there is a fuel delivery problem, refer to
Fuel System
Diagnosis
, which diagnoses the fuel injectors, the fuel
pressure regulator, and the fuel pump. If a malfunction
occurs in the fuel metering system, it usually results in
either a rich HO2S signal or a lean HO2S signal. This
condition is indicated by the HO2S voltage, which causes
the PCM to change the fuel calculation (fuel injector pulse
width) based on the HO2S reading. Changes made to the
fuel calculation will be indicated by a change in the long
term fuel trim values which can be monitored with a
Tech 2. Ideal long term fuel trim values are around 0%;
for a lean HO2S signal, the PCM will add fuel, resulting in
a fuel trim value above 0%. Some variations in fuel trim
values are normal because all engines are not exactly the
same. If the evaporative emission canister purge is ªONº,
the fuel trim may be as low as ±38%. If the fuel trim values
are greater than +23%, refer to
DTC P0131, DTC P0151,
DTC P0171, and DTC 1171
for items which can cause a
lean HO2S signal.
Fuel System Pressure Test
A fuel system pressure test is part of several of the
diagnostic charts and symptom checks. To perform this
test, refer to
Fuel Systems Diagnosis.
Fuel Injector Coil Test Procedure and
Fuel Injector Balance Test Procedure
T32003
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
2. Relieve the fuel pressure by connecting the J
34730-1 Fuel Pressure Gauge to the fuel pressure
connection on the fuel rail.
CAUTION: In order to reduce the risk of fire and
personal injury, wrap a shop towel around the fuel
pressure connection. The towel will absorb any fuel
leakage that occurs during the connection of the fuel
pressure gauge. Place the towel in an approved
container when the connection of the fuel pressure
gauge is complete.
Place the fuel pressure gauge bleed hose in an
approved gasoline container.
With the ignition switch ªOFFº, open the valve on the
fuel pressure gauge.
3. Record the lowest voltage displayed by the DVM
after the first second of the test. (During the first
second, voltage displayed by the DVM may be
inaccurate due to the initial current surge.)
Injector Specifications:
Resistance (Ohms)
Voltage Specification at
10
C-35
C (50
F-95
F)
11.8 ± 12.65.7 ± 6.6

The voltage displayed by the DVM should be within
the specified range.

The voltage displayed by the DVM may increase
throughout the test as the fuel injector windings
warm and the resistance of the fuel injector windings
changes.

6E±74
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

P1275, P1639, P1271, P1273

P1285, P1272, P1273

P0336, P0337

P1220, P1515, P1221, P1515, P1516

P1280, P1271, P1272
Check for the following conditions:

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 fs displayed value on the Tech 2 with
the ignition ªONº and the engine ªOFFº while you
move the connectors and the wiring harnesses
related to the following sensors:

Vapor Pressure (Fuel Tank Pressure) Sensor

MAP Sensor

EGR

TPS1/TPS2

APS1/APS2/APS3

CKP
Multiple PCM Information Sensor DTCs Set

StepActionValue(s)Ye sNo
1Was the ªOn-Board (OBD) System Checkº performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Turn the ignition ªOFFº, disconnect the PCM.
2. Turn the ignition ªONº, check the 5 volt reference 1
and 2 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?
ÐGo to Step 3Go to Step 4
3Repair the open or short.
Is the action complete?
ÐVerify repairÐ
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?
ÐGo to Step 5Go to Step 6
5Repair the open or the poor connection.
Is the action complete?
ÐVerify repairÐ
6Following below the DTCs stored:
P1635, P1639
Ð
Go to
applicable
DTC table
Go to Step 7
7 Measure the resistance below the items:

Between EGR sensor supply circuit and Vapor
Pressure Sensor supply circuit.

Between MAP sensor supply circuit and Vapor
Pressure Sensor supply circuit.

Between Vapor Pressure Sensor supply circuit
and PCM harness connector. (5Volt supply
circuit)
Is the resistance near the specified value?
ÐGo to Step 9Go to Step 8

6E±76
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Exhaust Gas Recirculation (EGR)
Diagnosis
An EGR flow check diagnosis of the linear EGR system is
covered by DTC P0401. Pintle position error diagnosis is
covered by DTC P0402, P0404, P1404, P0405, P0406. If
EGR diagnostic trouble codes P0401 and/or 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 Ð Tech 2 Displays YES or NO Ð
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 Ð Tech 2 Range 0.0-25.5 Ð
Air/fuel ratio indicates the PCM commanded value. In
closed loop, the air/fuel ratio should normally be
displayed around ª14.2-14.7º. 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 ÐTech 2 Range 0%-100% Ð
AP (accelerator pedal) angle is computed by the PCM
from the AP sensor voltage. AP angle should display
ª13%º at idle and ª85-89%º at wide open throttle.
AP2 ÐTech 2 Range 0%-100% Ð
AP (accelerator pedal) angle is computed by the PCM
from the AP sensor voltage. AP angle should display
ª85-89%º at idle and ª11-15%º at wide open throttle.
AP3 ÐTech 2 Range 0%-100% Ð
AP (accelerator pedal) angle is computed by the PCM
from the AP sensor voltage. AP angle should display
ª85-89%º at idle and ª32-36%º at wide open throttle.
BAROMETRIC PRESSURE Ð Tech 2 Range 10-105
kPa/0.00-5.00 Volts Ð
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 ª61-104º depending on
altitude and barometric pressure.
CHECK TRANS LAMP Ð AUTO TRANSMISSION Ð
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.
DESIRED EGR POS. Ð Tech 2 Range 0%-100% Ð
Represents the EGR pintle position that the PCM is
commanding.
DESIRED IDLE Ð Tech 2 Range 0-3187 RPM Ð
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 Ð (Engine Coolant Temperature) Tech 2
Range ±40
C to 151
C (±40
F to 304
F) Ð
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 Ð Tech 2 Range 0%-100% Ð
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 Ð Tech 2 Range 0.00-5.00 Volts Ð
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 Ð Tech 2 Range 0%-100% Ð
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 Ð Tech 2 Range
00:00:00-99:99:99 Hrs:Min:Sec Ð
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 Ð Range 0-9999 RPM Ð
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.
EVAP PURGE PWM Ð Tech 2 Range 0%-100% Ð
Represents the PCM commanded PWM duty cycle of the
EVAP purge solenoid valve. ª0%º displayed indicates no
purge; ª100%º displayed indicates full purge.
FUEL PUMP Ð Tech 2 Displays ON or OFF Ð
Indicates the PCM commanded state of the fuel pump
relay driver circuit.
HO2S BANK 1, SEN. 1
Ð Tech 2 Range 0-1132 mV Ð
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
Ð Tech 2 Range 0-1000mV Ð
Monitors the exhaust oxygen sensor output voltage. The
PCM 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
PCM 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.