1998 ISUZU TROOPER sensor

6E±146
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1486 (Flash DTC 74)
ITP (Intake Throttle Position) Sensor High Voltage
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 P1486 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
ITP sensor display on the Tech 2 while moving
connectors and wiring harnesses related to the TP
sensor. A change in the display will indicate the
location of the fault.

Faulty TP sensor ± With the ignition key ªON,º engine
ªOFF,º observe the TP sensor display on the Tech 2
while slowly depressing the accelerator to wide open
throttle.
If DTC P1486 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±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±152
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0502 (Flash DTC 24)
VSS (Vehicle Speed Sensor) No Signal
060RW136
Circuit Description
The vehicle speed sensor has a magnet rotated by the
transmission output shaft. Attached to the sensor is a hall
effect circuit the interacts with the magnetic field treated
by the rotating magnet. A 12-volt operating supply for the
speed sensor hall circuit is supplied from the meter fuse.
The VSS pulses to ground the 9-volt signal sent from the
engine control module (ECM) on the reference circuit.
The ECM interprets vehicle speed by the number of
pulses to ground per second on the reference circuit.
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 P0502 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the ECM battery
feed.

6E±153 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
10. To avoid backprobing the VSS and possibly
damaging a seal or terminal, the VSS output can be
tested at the point where the transmission harness
connected to the engine harness. The green 16-way
connector is adjacent to a blue 16-way connector,
and it can be easily accessed by removing the air
cleaner assembly. The green 16-way connector is
separated, and battery voltage is applied to the VSS
through the yellow wire at one corner of the
connector. The VSS output can be monitored with a
DVM connected to the blue wire with a black tracer.
The two wires are next to each other in the 16-way
connector . The test connections are made on the
transmission side of the connector, the side that is
not clipped to the body sheetmetal.11. The speedometer-to-ECM VSS signal wire is
spliced to a wire leading to the cruise control
module. If a short to ground or voltage is found
between the ECM and speedometer, it could be
located between the splice and the cruise control
module.
DTC P0502 ±VSS No Signal

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Does the speedometer work?ÐGo to Step 10Go to Step 3
31. Disconnect the VSS connector.
2. Ignition ªON.º
3. Using a test light to battery +, probe the connector
ground wire.
Did the light illuminate?
ÐGo to Step 5Go to Step 4
4Repair the sensor ground.
Is the action complete?
ÐVerify repairÐ
51. Ignition ªON,º sensor disconnected.
2. Using a DVM, measure at the VSS connector
between ground and voltage supply.
Was the measurement near the specified value?
Battery
voltage
Go to Step 7Go to Step 6
6Repair the open or short to ground which may have
blown the meter fuse.
Is the action complete?
ÐVerify repairÐ
71. Ignition ªON,º VSS disconnected.
2. Using a DVM, measure at the VSS connector
between ground and the blue/black wire from the
speedometer.
Was the measurement near the specified value?
7.5-8 VGo to Step 9Go to Step 8
8Check for an open or short circuit between the
speedometer and the VSS.
Was an open or short circuit located?
ÐVerify repairGo to Step 9
9Replace the VSS.
Is the action complete?
ÐVerify repairGo to Step 10
10Replace the speedometer.
Is the action complete?
ÐVerify repairGo to Step 11

6E±174
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1589 (Flash DTC 47)
Transmission SW Circuit Open/Short
060RW131
Circuit Description
The trans mission SW circuit receives current through
ELEC IG 10A fuse from the battery, current flowing in the
order of the trans mission SW and ECM.
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 P1589 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 TP
sensor. A change in the display will indicate the
location of the fault.
If DTC P1589 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.
DTC P1589 ± Transmission Circuit Open/Short

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Check the Fuse 10A for a open circuit and replace the
Fuse if necessary.
Did the Fuse require replacement?
ÐVerify repairGo to Step 3