1998 ISUZU TROOPER reset

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 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 ª14.2-14.7.º 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 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.
CMP ACT. COUNTER ± Cam Position Activity
DECEL FUEL MODE Ð Tech 2 Display ACTIVE or
INACTIVE Ð
ªACTIVEº 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. 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.
FUEL PUMP Ð Tech 2 Displays ON or OFF Ð
Indicates the PCM commanded state of the fuel pump
relay driver circuit.
FUEL TRIM CELL Ð Tech 2 Range 0-21 Ð
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 Ð Tech 2 Displays NO or YES
Ð
When conditions are appropriate for enabling long term
fuel trim corrections, fuel trim learn will display ªYES.º
This indicates that the long term fuel trim is responding to
the short term fuel trim. If the fuel trim learn displays
ªNO,º then long term fuel trim will not respond to changes
in short term fuel trim.
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.

6E±71 ENGINE DRIVEABILITY AND EMISSIONS
3.2/3.5L V-6 Engine
Tech 2
Parameter
Data ListUnits
DisplayedTypical Data
Values (IDLE)Typical Data
Values
(2500 RPM)Refer To
A/C ClutchEngineOn/OffOffOffGeneral Description and
Operation, A/C Clutch
Circuit Operation
A/C RequestEngineYes/NoNoNoGeneral Description and
Operation, A/C Request
Signal
Air/Fuel RatioEngineRatio: _ to
114.714.7General Description and
Operation, Fuel System
Metering Purpose
Barometric
PressureEnginekPa61-104 (depends
on altitude and
barometric)61-104 (depends
on altitude and
barometric)General Description and
Operation
CMP Act.
Counter (Cam
Position Activity)EngineCounts0-255, always
increasing0-255, always
increasingDTC P0341 and P0342
Decel Fuel
ModeEngineActive/Inac
tiveInactiveInactiveGeneral Description and
Operation, Deceleration
Mode
Desired EGR
PositionEnginePercent0%0%General Description and
Operation, EGR Pintle
Position Sensor
Desired IdleEngineRPM750ÐGeneral Description and
Operation, Idle Air Control
(IAC) Valve
ECT (Engine
Coolant Temp)EngineDegrees C,
Degrees F80-100
C
(176-212
F)80-100
C
(176-212
F)General Description and
Operation, Engine Coolant
Temperature (ECT) Sensor
EGR Closed
Valve Pintle
PositionEngineSteps20-4020-40General Description and
Operation, EGR Pintle
Position Sensor
EGR Duty CycleEnginePercent0%0%General Description and
Operation, Linear EGR
Operation and Results of
Incorrect Operation
EGR FeedbackEngineVolts0.45-0.800.45-0.80Ð
EGR
NormalizedEnginePercent0%0%Ð
Engine LoadEnginePercent2.0% - 5.5%8.0% - 16.0%General Description and
Operation, Mass Air Flow
(MAF) Sensor
Time From StartEngineSecVaries. Resets at
each engine
start.Varies. Resets at
each engine
start.
Ð
Engine SpeedEngineRPMWithin ±50 to
+100 of ªDesired
IdleºActual engine
speedDTCs: P1508, P1509
Fuel PumpEngineOn/OffOnOnEngine Fuel
HO2S Bank 1
Sen.1 (millivolts)O2 Sensor
DataMillivolts50-950 changing
quickly50-950, always
changing quicklyGeneral Description and
Operation, Fuel control
HO2S

6E±93 ENGINE DRIVEABILITY AND EMISSIONS
Idle Air Control (IAC) System Check
Circuit Description
The powertrain control module (PCM) controls engine
idle speed with the idle air control (IAC) valve. To increase
idle speed, the PCM retracts the IAC valve pintle away
from its seat, allowing more air to bypass the throttle bore.
To decrease idle speed, it extends the IAC valve pintle
towards its seat, reducing by pass air flow. Tech 2 will
read the PCM commands to the IAC valve in counts.
Higher counts indicate more air bypass (higher idle).
Lower counts indicate less air is allowed to bypass (lower
idle).
Diagnostic Aids
A slow, unstable, or fast idle may be caused by a non-IAC
system problem that cannot be overcome by the IAC
valve. Out of control range IAC Tech 2 counts will be
above 60 if idle is too low, and zero counts if idle is too
high. The following checks should be made to repair a
non-IAC system problem:

Vacuum leak (high idle) ± If idle is too high, stop the
engine. Fully extend (low) IAC with the Tech 2. Start
the engine. If idle speed is above 800 RPM, locate and
correct the vacuum leak, including the PCV system.
Check for binding of the throttle blade or linkage.

Lean heated oxygen sensor signal (high air/fuel ratio) ±
The idle speed may be too high or too low. Engine
speed may vary up and down, and disconnecting the
IAC valve does not help. Diagnostic trouble codes
P0131, P0151, P0171, or P0174 may be set. Tech 2
oxygen (O2) voltage will be less than 100 mV (0.1 V).
Check for low regulated fuel pressure, water in fuel, or
a restricted injector.

Rich heated oxygen sensor signal (low air/fuel ratio) ±
The idle speed will be too low. Tech 2 IAC counts will
usually be above 80. The system is obviously rich and
may exhibit black smoke in the exhaust.
Tech 2 O2 voltage will be fixed at about 750 mV (0.75
V). Check for high fuel pressure, or a leaking or
sticking injector. A silicon-contaminated heated
oxygen sensor will show an O2 voltage slow to
respond on Tech 2.
Throttle body ± Remove the IAC valve and inspect the
bore for foreign material.

IAC valve electrical connections ± IAC valve
connections should be carefully checked for proper
contact.

PCV valve ± An incorrect or faulty PCV valve may
result in an incorrect idle speed. Refer to
Diagnosis,
Rough Idle, Stalling.
If intermittent poor driveability or
idle symptoms are resolved by disconnecting the IAC,
carefully recheck the connections and valve terminal
resistance, or replace the IAC.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
1. The Tech 2 is used to extend and retract the IAC
valve. Valve movement is verified by an engine
speed change. If no change in engine speed
occurs, the valve can be resettled when removed
from the throttle body.
2. This step checks the quality of the IAC movement in
step 1. Between 700 revolutions per minute (RPM)
and about 1500 RPM, the engine speed should
change smoothly with each flash of the tester light
in both extend and retract. If the IAC valve is
retracted beyond the control range (about 1500
RPM), it may take many flashes to extend the IAC
valve before engine speed will begin to drop. This
is normal on certain engines. Fully extending the
IAC may cause engine stall. This may be normal.

6E±171 ENGINE DRIVEABILITY AND EMISSIONS
If the test light blinks while cranking, the PCM and
the wiring to the injectors are OK. The Fuel Injector
Coil Test Procedure will check if the injectors are
faulty.
R321054
7. Because the test light was ªONº steady, voltage to
the injector is OK, but the driver circuit is grounded
at all times. This step determines if the circuit is
shorted to ground or the PCM is faulty.
9. The reading should be about 12-14
.
10.Locating the open in the harness or in the injector
will require removal of the manifold to provide
access.
DTC P0201 ± Injector 1 Control Circuit

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Will the engine start?
ÐGo to Step 3
Go to Engine
Cranks But
Will Not Run
chart
31. Install the Tech 2. Clear the DTC.
2. Idle the engine for one minute.
Does DTC P0201 reset?
ÐGo to Step 5Go to Step 4
41. Review the Freeze Frame data with the ignition
ªONº and the engine ªOFFº and note the
parameters.
2. Operate the vehicle within the Freeze Frame
conditions as noted.
Does P0201 reset?
ÐGo to Step 5
Go to
Diagnostic
Aids
51. Engine ªOFF.º
2. Disconnect the injector connector.
3. Install an injector test light 5-8840-2636-0 on the
injector test connector.
4. Crank the engine and note the light.
Does the injector test light blink?
Ð
Go to Fuel
Injector Coil
Test
Procedure
Go to Step 6
6Note whether the injector test light for cylinder 1 was
ªOFFº or ªONº steady in step 5.
Was the test light ªONº steady while cranking the
engine?
ÐGo to Step 7Go to Step 9

6E±174
ENGINE DRIVEABILITY AND EMISSIONS
If the test light blinks while cranking, the PCM and
the wiring to the injectors are OK. The Fuel Injector
Coil Test Procedure will check if the injectors are
faulty.
R321055
7. Because the test light was ªONº steady, voltage to
the injector is OK, but the driver circuit is grounded
at all times. This step determines if the circuit is
shorted to ground or the PCM is faulty.
9.The reading should be about 12-14
.
10.Locating the open in the harness or in the injector
will require removal of the manifold to provide
access.
DTC P0202 ± Injector 2 Control Circuit

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Will the engine start?
ÐGo to Step 3
Go to Engine
Cranks But
Will Not Run
chart
31. Install the Tech 2. Clear the DTC.
2. Idle the engine for one minute.
Does DTC P0202 reset?
ÐGo to Step 5Go to Step 4
41. Review the Freeze Frame data with the ignition
ªONº and the engine ªOFFº and note the
parameters.
2. Operate the vehicle within the Freeze Frame
conditions as noted.
Does P0202 reset?
ÐGo to Step 5
Go to
Diagnostic
Aids
51. Engine ªOFF.º
2. Disconnect the injector test connector.
3. Install an injector test light 5-8840-2636-0 on
injector connector.
4. Crank the engine and note the light.
Does the cylinder 2 test light blink?
Ð
Go to Fuel
Injector Coil
Test
Procedure
Go to Step 6
6Note whether the injector test light for cylinder 2 was
ªOFFº or ªONº steady in step 5.
Was the test light ªONº steady while cranking the
engine?
ÐGo to Step 7Go to Step 9

6E±177 ENGINE DRIVEABILITY AND EMISSIONS
If the test light blinks while cranking, the PCM and
the wiring to the injectors are OK. The Fuel Injector
Coil Test Procedure will check if the injectors are
faulty.
R321056
7. Because the test light was ªONº steady, voltage to
the injector is OK, but the driver circuit is grounded
at all times. This step determines if the circuit is
shorted to ground or the PCM is faulty.
9. The reading should be about 12-14
.
10.Locating the open in the harness or in the injector
will require removal of the manifold to provide
access.
DTC P0203 ± Injector 3 Control Circuit

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Will the engine start?
ÐGo to Step 3
Go to Engine
Cranks But
Will Not Run
chart
31. Install the Tech 2. Clear the DTC.
2. Idle the engine for one minute.
Does DTC P0203 reset?
ÐGo to Step 5Go to Step 4
41. Review the Freeze Frame data with the ignition
ªONº and the engine ªOFFº and note the
parameters.
2. Operate the vehicle within the Freeze Frame
conditions as noted.
Does P0203 reset?
ÐGo to Step 5
Go to
Diagnostic
Aids
51. Engine ªOFF.º
2. Disconnect the injector test connector .
3. Install an injector test light 5-8840-2636-0 on
injector connector.
4. Crank the engine and note the light.
Does the cylinder 3 test light blink?
Ð
Go to Fuel
Injector Coil
Test
Procedure
Go to Step 6
6Note whether the injector test light for cylinder 3 was
ªOFFº or ªONº steady in step 5.
Was the test light ªONº steady while cranking the
engine?
ÐGo to Step 7Go to Step 9

6E±180
ENGINE DRIVEABILITY AND EMISSIONS
If the test light blinks while cranking, the PCM and
the wiring to the injectors are OK. The Fuel Injector
Coil Test Procedure will check if the injectors are
faulty.
R321057
7. Because the test light was ªONº steady, voltage to
the injector is OK, but the driver circuit is grounded
at all times. This step determines if the circuit is
shorted to ground or the PCM is faulty.
9. The reading should be about 12-14
.
10.Locating the open in the harness or in the injector
will require removal of the manifold to provide
access.
DTC P0204 ± Injector 4 Control Circuit

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Will the engine start?
ÐGo to Step 3
Go to Engine
Cranks But
Will Not Run
chart
31. Install the Tech 2. Clear the DTC.
2. Idle the engine for one minute.
Does DTC P0204 reset?
ÐGo to Step 5Go to Step 4
41. Review the Freeze Frame data with the ignition
ªONº and the engine ªOFFº and note the
parameters.
2. Operate the vehicle within the Freeze Frame
conditions as noted.
Does P0204 reset?
ÐGo to Step 5
Go to
Diagnostic
Aids
51. Engine ªOFF.º
2. Disconnect the injector test connector.
3. Install an injector test light 5-8840-2636-0 on
injector connector.
4. Crank the engine and note the light.
Does the cylinder 4 test light blink?
Ð
Go to Fuel
Injector Coil
Test
Procedure
Go to Step 6
6Note whether the injector test light for cylinder 4 was
ªOFFº or ªONº steady in step 5.
Was the test light ªONº steady while cranking the
engine?
ÐGo to Step 7Go to Step 9

6E±183 ENGINE DRIVEABILITY AND EMISSIONS
If the test light blinks while cranking, the PCM and
the wiring to the injectors are OK. The Fuel Injector
Coil Test Procedure will check if the injectors are
faulty.
R321058
7. Because the test light was ªONº steady, voltage to
the injector is OK, but the driver circuit is grounded
at all times. This step determines if the circuit is
shorted to ground or the PCM is faulty.
9. The reading should be about 12-14
.
10.Locating the open in the harness or in the injector
will require removal of the manifold to provide
access.
DTC P0205 ± Injector 5 Control Circuit

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Will the engine start?
ÐGo to Step 3
Go to Engine
Cranks But
Will Not Run
chart
31. Install the Tech 2. Clear the DTC.
2. Idle the engine for one minute.
Does DTC P0205 reset?
ÐGo to Step 5Go to Step 4
41. Review the Freeze Frame data with the ignition
ªONº and the engine ªOFFº and note the
parameters.
2. Operate the vehicle within the Freeze Frame
conditions as noted.
Does P0205 reset?
ÐGo to Step 5
Go to
Diagnostic
Aids
51. Engine ªOFF.º
2. Disconnect the injector test connector.
3. Install an injector test light 5-8840-2636-0 on
injector connector.
4. Crank the engine and note the light.
Does the cylinder 5 test light blink?
Ð
Go to Fuel
Injector Coil
Test
Procedure
Go to Step 6
6 Note whether the injector test light for cylinder 5 was
ªOFFº or ªONº steady in step 5.
Was the test light ªONº steady while cranking the
engine?
ÐGo to Step 7Go to Step 9