check engine OPEL FRONTERA 1998 Workshop Manual

6E–143 4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
DTC P1475 – EXH #2 VSV Circuit Open/Short
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. Ignition “ON,” engine “OFF.” Review and record
Tech 2 Failure Records data.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor the “ DTC” info for DTC
P1475.
Does the Tech 2 indicate DTC P1475 failed this
ignition?
—Go to Step 3
Refer to
Diagnostic
Aids
31. Ignition “OFF.”
2. Disconnect the EXH #2 connectors.
3. Check the EXH #2 circuit for a short to ground.
Is the EXH #2 circuit shorted to ground?
—Verify repairGo to Step 4
4Replace the EXH #2 VSV.
Is the action complete?
—Verify repairGo to Step 5
51. Ignition “ON,” engine “OFF.” Review and record
Tech 2 Failure Records data.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor the “ DTC” info for DTC
P1475.
Does the Tech 2 indicate DTC P1475 failed this
ignition?
—Go to Step 6—
6Replace the ECM (Refer to the Data Programming in
Case of ECM change).
Is the action complete?
—Verify repair—

6E–144
4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1485 (Flash DTC 74)
ITP (Intake Thorottle Position) Sensor Low 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 P1485 can be cleared by using the Tech 2 “Clear
Info” 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 P1485 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 P1485 –ITP Sensor Low Voltage
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. Ignition “ON,” engine “OFF.”
2. With the throttle closed by the hand, observe the
“ITP Sensor” display on the Tech 2.
Is the “ITP Sensor” below the specified value?
0.22 VGo to Step 4Go to Step 3

6E–145 4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
DTC P1485 –ITP Sensor Low Voltage
StepNo Ye s Va l u e ( s ) Action
31. Ignition “ON,” engine “OFF.”
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 “DTC” info for DTC
P1485.
Does the Tech 2 indicate DTC P1485 failed?
—Go to Step 4
Refer to
Diagnostic
Aids
4Check the ITP sensor signal circuit for a poor
connection at the ECM and replace the terminal if
necessary.
Did the terminal require replacement?
—Verify repairGo to Step 5
51. Ignition “ON,” engine “OFF.”
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 “Specific DTC” info for
DTC P1485.
Dose the Tech 2 indicate DTC P1485 failed?
—Go to Step 6
Refer to
Diagnostic
Aids
6Replace the intake throttle.
Is the action complete?
—Verify repairGo to Step 7
7Replace the ECM (Refer to the Data Programming in
Case of ECM change).
Is the action complete?
—Verify repair—

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 “Clear
Info” 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 “ON,” engine
“OFF,” 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
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. Ignition “ON,” engine “OFF.”
2. With the throttle closed by the hand, observe the
“ITP Sensor” display on the Tech 2.
Is the “ITP Sensor” above the specified value?
4.88 VGo to Step 4Go to Step 3
31. Ignition “ON,” engine “OFF.”
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 “DTC” info for DTC P1486.
Does the Tech 2 indicate DTC P1486 failed.
—Go 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?
—Verify repairGo to Step 5
51. Ignition “ON,” engine “OFF.”
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 “DTC” info for DTC
P1486.
Dose the Tech 2 indicate DTC P1486 failed.
—Go to Step 6
Refer to
Diagnostic
Aids
6Replace the intake throttle.
Is the action complete?
—Verify repairGo to Step 7
7Replace the ECM (Refer to the Data Programming in
Case of ECM change).
Is the action complete?
—Verify repair—

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 “Clear
Info” 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–149 4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
DTC P1487 – Intake Throttle System Circuit Open/Short
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. Ignition “ON,” engine “OFF.”
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 “DTC” info for DTC
P1487.
Does the Tech 2 indicate DTC P1487 failed?
—Go to Step 3
Refer to
Diagnostic
Aids
3Check the ITP circuit for a poor connection at the ECM
and ITP and replace the terminal if necessary.
Did the terminal require replacement?
—Verify repairGo to Step 4
41. Ignition “ON,” engine “OFF.”
2. Operate the throttle by the hand.
Is the action complete?
—Verify repairGo to Step 5
5Replace the ITP Assembly.
Is the action complete?
—Verify repairGo to Step 6
6Replace the ECM (Refer to the Data Programming in
Case of ECM change).
Is the action complete?
—Verify repair—

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 “Clear
Info” 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
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. Ignition “ON,” engine “OFF.”
2. With the throttle closed, observe the “ITP Sensor”
display on the Tech 2.
Is the “ITP Sensor” below the specified value?
0.22 VGo to Step 4Go to Step 3
31. Ignition “ON,” engine “OFF.”
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 “Specific DTC” info for
DTC P1488.
Does the Tech 2 indicate DTC P1488 failed?
—Go 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?
—Verify 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?
—Verify 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?
—Verify repairGo to Step 7
7Replace the ECM (Refer to the Data Programming in
Case of ECM change).
Is the action complete?
—Verify repair—

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
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
2Does the speedometer work?—Go to Step 10Go to Step 3
31. Disconnect the VSS connector.
2. Ignition “ON.”
3. Using a test light to battery +, probe the connector
ground wire.
Did the light illuminate?
—Go to Step 5Go to Step 4
4Repair the sensor ground.
Is the action complete?
—Verify repair—
51. Ignition “ON,” 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?
—Verify repair—
71. Ignition “ON,” 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?
—Verify repairGo to Step 9
9Replace the VSS.
Is the action complete?
—Verify repairGo to Step 10
10Replace the speedometer.
Is the action complete?
—Verify repairGo to Step 11