1998 ISUZU TROOPER Intake sensor

6E±147 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
DTC P1486 ± ITP Sensor High Voltage

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Ignition ªON,º engine ªOFF.º
2. With the throttle closed by the hand, observe the
ªITP Sensorº display on the Tech 2.
Is the ªITP Sensorº above the specified value?
4.88 VGo to Step 4Go to Step 3
31. Ignition ªON,º engine ªOFF.º
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor ªDTCº info for DTC P1486.
Does the Tech 2 indicate DTC P1486 failed.
ÐGo to Step 4
Refer to
Diagnostic
Aids
4Check for poor electrical connections at the ITP sensor
and replace terminals if necessary.
Did any terminals require replacement?
ÐVerify repairGo to Step 5
51. Ignition ªON,º engine ªOFF.º
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2 monitor the ªDTCº info for DTC
P1486.
Dose the Tech 2 indicate DTC P1486 failed.
ÐGo to Step 6
Refer to
Diagnostic
Aids
6Replace the intake throttle.
Is the action complete?
ÐVerify repairGo to Step 7
7Replace the ECM (Refer to the Data Programming in
Case of ECM change).
Is the action complete?
ÐVerify repairÐ

6E±148
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1487 (Flash DTC 73)
Intake Throttle System Circuit Open/Start
060RW134
Circuit Description
The intake throttle position (ITP) sensor circuit provides a
voltage signal that changes relative to throttle blade
angle.
Action Taken When the DTC Sets

The ECM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.

The ECM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC

DTC P1487 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the ECM battery
feed.
Diagnostic Aids
Check for the following conditions:

Poor connection at ECM ± Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.

Damaged harness ± Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
throttle position display on the Tech 2 while moving
connectors and wiring harnesses related to the ITP
sensor. A change in the display will indicate the
location of the fault.
If DTC P1487 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.

6E±150
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1488 (Flash DTC 72)
Intake Throttle Motor Control Circuit Signal Gap
060RW135
Circuit Description
The Intake throttle position (ITP) sensor circuit provides a
voltage signal that changes relative to throttle blade
angle.
Action Taken When the DTC Sets

The ECM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC

DTC P1488 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the ECM battery
feed.
Diagnostic Aids
Check for the following conditions:

Poor connection at ECM ± Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.

Damaged harness ± Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
throttle position display on the Tech 2 while moving
connectors and wiring harnesses related to the ITP
sensor. A change in the display will indicate the
location of the fault.
If DTC P1488 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.

6E±151 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
DTC P1488 ± Intake Throttle Motor Control Circuit Signal Gap

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Ignition ªON,º engine ªOFF.º
2. With the throttle closed, observe the ªITP Sensorº
display on the Tech 2.
Is the ªITP Sensorº below the specified value?
0.22 VGo to Step 4Go to Step 3
31. Ignition ªON,º engine ªOFF.º
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor the ªSpecific DTCº info for
DTC P1488.
Does the Tech 2 indicate DTC P1488 failed?
ÐGo to Step 4
Refer to
Diagnostic
Aids
4Check the ITP circuit for a poor connection at the ECM
and replace the terminal if necessary.
Did the terminal require replacement?
ÐVerify repairGo to Step 5
5Check the Intake throttle motor circuit for a poor
connection and replace the terminal if necessary.
Did the terminal require replacement?
ÐVerify repairGo to Step 6
6Check the ITP Assembly for a poor connection at the
TP sensor and fasten the ITP Assembly if necessary.
Did the ITP Assembly require repair?
ÐVerify repairGo to Step 7
7Replace the ECM (Refer to the Data Programming in
Case of ECM change).
Is the action complete?
ÐVerify repairÐ

6E±176
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Symptom Diagnosis
Preliminary Checks
Before using this section, perform the ªOn±Board
Diagnostic (OBD) System Checkº and verify all of the
following items:

The powertrain control module (ECM) and
malfunction indicator lamp (MIL) (CHECK ENGINE
lamp) are operating correctly.

There are no DTC(s) stored.

Tech±2 data is within normal operating range. Refer
to
Typical Scan Data Values.

Verify the customer complaint and locate the correct
symptom in the table of contents. Perform the
procedure included in the symptom chart.
Visual/Physical Check
Several of the symptom procedures call for a careful
visual/physical check. This can lead to correcting a
problem without further checks and can save valuable
time.
This check should include the following items:

ECM grounds for cleanliness, tightness and proper
location.

Vacuum hoses for splits, kinks, and proper
connections, as shown on the ªVehicle Emission
Control Informationº label. Check thoroughly for any
type of leak or restriction.

Air intake ducts for collapsed or damaged areas.

Injector wires for cracking, hardness, and carbon
tracking.

Wiring for proper connections, pinches and cuts.
Intermittents
IMPORTANT:An intermittent problem may or may not
turn on the malfunction indicator lamp (MIL) or store a
DTC. DO NOT use the Diagnostic Trouble Code (DTC)
charts for intermittent problems. The fault must be
present to locate the problem.
Most intermittent problems are caused by faulty electrical
connections or wiring. Perform a careful visual/physical
check for the following conditions:

Poor mating of the connector halves or a terminal not
fully seated in the connector (backed out).

Improperly formed or damaged terminal.

All connector terminals in the problem circuit should
be carefully checked for proper contact tension.

Poor terminal±to±wire connection. This requires
removing the terminal from the connector body to
check.
Road test the vehicle with a Digital Multimeter
(5-8840-0285-0) connected to a suspected circuit. An
abnormal voltage when the malfunction occurs is a good
indication that there is a fault in the circuit being
monitored.
Use a scan tool to help detect intermittent conditions. The
scan tools have several features that can be used to
locate an intermittent condition. Use the following feature
to find intermittent faults:
Using a Tech±2 ªFreeze Frameº buffer or ªFailure
Recordsº buffer can aid in locating an intermittent
condition. Review and record the information in the
freeze frame or failure record associated with the
intermittent DTC being diagnosed. The vehicle can
be driven within the conditions that were present
when the DTC originally set.
To check for loss of diagnostic code memory, disconnect
the MAP sensor and idle the engine until the MIL (CHECK
ENGINE lamp) comes on. DTC P0107 should be stored
and kept in memory when the ignition is turned ªOFF.º If
not, the ECM is faulty. When this test is completed, make
sure that you clear the DTC P0107 from memory.
An intermittent MIL (CHECK ENGINE lamp) with no
stored DTC may be caused by the following:

MIL (CHECK ENGINE lamp) wire to ECM shorted to
ground.

Poor ECM grounds. Refer to the ECM wiring
diagrams.
Check for improper installation of electrical options such
as lights, cellular phones, etc.
Check for an open diode across the A/C compressor
clutch and check for other open diodes (refer to wiring
diagrams in
Electrical Diagnosis).
If problem has not been found, refer to
ECM Connector
Symptom
tables.

6E±181 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Lack of Power, Sluggish or Spongy Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
Engine delivers less than expected power. Little or no
increase in speed when accelerator pedal is pushed
down part-way.
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
ÐVerify repairGo to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to Visual/
Physical
Check
41. Remove and check the air filter element for dirt or
restrictions. Refer to
Air Intake System in
On-Vehicle Service.
2. Replace the air filter element if necessary.
Was a repair required?
ÐVerify repairGo to Step 5
51. Check AP sensor system. Refer to AP sensor
diagnostic
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 6
61. Check for water-or alcohol-contaminated fuel.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
71. Using a Tech 2, Injector test.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
81. Check the ECM grounds for the cleanliness,
tightness and proper locations. Refer to the ECM
wiring diagrams in
Electrical Diagnosis.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9
91. Check the exhaust system for possible restriction:

Inspect the exhaust system for damaged or
collapsed pipes.

Inspect the muffler for heat distress or possible
internal failure.

Check for a possible plugged catalytic
converter by checking the exhaust system
back pressure. Refer to
Restricted Exhaust
System Check
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 10
101. Check the torque converter clutch (TCC) for proper
operation. Refer to
Transmission Diagnosis.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 11

6E±186
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Poor Fuel Economy Symptom

 
StepNo Ye s Value(s) Action
111. Check the TCC operation. Refer to Transmission
Diagnosis
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 12
121. Check the exhaust system for possible restriction:

Inspect the exhaust system for damaged or
collapsed pipes.

Inspect the muffler for heat distress or possible
internal failure.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 13
13Check for proper calibration of the speedometer.
Does the speed indicated on the speedometer closely
match the vehicle speed displayed on the Tech 2?
ÐGo to Step 15Go to Step 14
14Diagnose and repair an inaccurate speedometer
condition as necessary. Refer to
Vehicle Speed
Sensor
in Electrical Diagnosis.
Was a problem found?
ÐVerify repairÐ
151. Check the air intake system and the crankcase for
air leaks. Refer to
Air Intake System and
Crankcase Ventilation System.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 16
161. Review all diagnostic procedures within this table.
2. When all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records buffer

All connections within a suspected circuit
and/or system.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 17
17Perform the procedure in Injector Test.
Was the fuel pressure normal?
Ð
Contact
Technical
Assistance
Verify repair

6E±203 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Engine Coolant Temperature
(ECT) Sensor
Removal Procedure
NOTE: Care must be taken when handling the engine
coolant temperature (ECT) sensor. Damage to the ECT
sensor will affect proper operation of the fuel injection
system.
1. Disconnect the negative battery cable.
2. Drain the radiator coolant. Refer to
Draining and
Refilling Cooling System
in Engine Cooling.
3. Disconnect the electrical connector.
4. Remove the ECT sensor from the front side of the
intake manifold.
035RW058
Installation Procedure
1. Apply sealer (LOCTITE 262) or the equivalent to the
threads of the ECT sensor.
2. Install the ECT sensor in the front side of the intake
manifold.
Tighten

Tighten the ECT sensor to 19 N´m (14 lb ft.).
3. Connect the electrical connector.
035RW058
4. Fill the radiator with coolant. Refer to Draining and
Refilling Cooling System
in Engine Cooling.
5. Connect the negative battery cable.
Intake Air Temperature (IAT)
Sensor
Removal Procedure
1. Disconnect the negative battery cable.
2. Disconnect the electrical connector from the IAT
sensor.
3. Remove the IAT sensor from the intake air duct by
using a rocking motion while pulling the sensor.
035RW056