1998 ISUZU TROOPER check engine light

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±175 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0202 ± Injector 2 Control Circuit

 
StepNo Ye s Value(s) Action
71. Disconnect the PCM connector for the affected
injectors.
2. With a test light connected to B+, probe the affected
injector driver circuit.
Does the test light illuminate?
ÐGo to Step 8Go to Step 15
8Repair short to ground in the injector driver circuit.
Is the action complete?
Ð
Go to OBD
System
Check
Ð
91. Disconnect the injector test connector.
2. At the injector side of the harness, connect an
ohmmeter between the positive wire (red with blue
tracer) and the wire for cylinder 2 (green with orange
tracer).
Does the ohmmeter indicate continuity?
ÐGo to Step 11Go to Step 10
10Repair the open injector harness wire or open injector.
Is the action complete?
ÐVerify repairÐ
11At the PCM side of the injector test connector, check
the green/orange wire for a short to voltage.
Was there a short to voltage?
ÐGo to Step 12Go to Step 13
12Repair the short to voltage.
Is the action complete?
ÐVerify repairÐ
13Check for an open circuit between the injector test
connector and the PCM.
Was there an open circuit?
ÐGo to Step 14Go to Step 15
14Repair the open circuit.
Is the action complete?
ÐVerify repairÐ
15Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±176
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0203 Injector 3 Control Circuit
D06RW034
Circuit Description
The powertrain control module (PCM) has six individual
injector driver circuits. Each controls an injector. When
the driver circuit is grounded by the PCM, the injector is
activated. The PCM monitors the current in each driver
circuit. The voltage on each driver is monitored to detect
a fault. If the voltage is not what the PCM expects to
monitor on the circuit, a DTC is set. This DTC is also set if
an injector driver is shorted to voltage or if there is an open
circuit.
Conditions for Setting the DTC

The battery voltage is more than 9 volts.

The engine is turning, determined by the 58X
crankshaft position input signal.

The injector voltage does not equal the ignition voltage
when the injector is commanded ªOFFº or the injector
voltage does not equal 0 volts when the injector is
commanded ªON.º

The above conditions are met for 15 seconds.
Action Taken When the DTC Sets

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

The PCM 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 P0203 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
An injector driver circuit that is open or shorted to voltage
will cause a DTC P0203 to set. It will also cause a misfire
due to an inoperative injector. A misfire DTC will also be
set indicating which cylinder is inoperative.
Long term and short term fuel trims that are excessively
high or low are a good indication that an injector is faulty.
Use Fuel Injector Coil Test Procedure to check for faulty
injectors.
Test Description
The number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. This step determines if DTC P0203 is the result of a
hard failure or an intermittent condition.
5. A special injector test connector is provided so that
the injectors can be electrically tested without
removal of the manifold. On the Trooper, the
special 7-way gray connector is located at the front
of the charcoal canister. The test connector can be
identified by the blue connector lock which is
tethered to the wiring harness. If the light for
cylinder 3 is ªONº steady before cranking the engine
as well as while cranking the engine, then the
injector driver circuit is shorted to ground.

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±178
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0203 ± Injector 3 Control Circuit

 
StepNo Ye s Value(s) Action
71. Disconnect the PCM connector for the affected
injectors.
2. With a test light connected to B+, probe the affected
injector driver circuit.
Does the test light illuminate?
ÐGo to Step 8Go to Step 15
8Repair short to ground in the injector driver circuit.
Is the action complete?
Ð
Go to OBD
System
Check
Ð
91. Disconnect the injector test connector.
2. At the injector side of the harness, connect an
ohmmeter between the positive wire (red with blue
tracer) and the wire for cylinder 3 (green).
Does the ohmmeter indicate continuity?
ÐGo to Step 11Go to Step 10
10Repair the open injector harness wire or open injector.
Is the action complete?
ÐVerify repairÐ
11At the PCM side of the injector test connector, check
the green wire for a short to voltage.
Was there a short to voltage?
ÐGo to Step 12Go to Step 13
12Repair the short to voltage.
Is the action complete?
ÐVerify repairÐ
13Check for an open circuit between the injector test
connector and the PCM.
Was there an open circuit?
ÐGo to Step 14Go to Step 15
14Repair the open circuit.
Is the action complete?
ÐVerify repairÐ
15Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±179 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0204 Injector 4 Control Circuit
D06RW034
Circuit Description
The powertrain control module (PCM) has six individual
injector driver circuits. Each controls an injector. When
the driver circuit is grounded by the PCM, the injector is
activated. The PCM monitors the current in each driver
circuit. The voltage on each driver is monitored to detect
a fault. If the voltage is not what the PCM expects to
monitor on the circuit, a DTC is set. This DTC is also set if
an injector driver is shorted to voltage or if there is an open
circuit.
Conditions for Setting the DTC

The battery voltage is more than 9 volts.

The engine is turning, determined by the 58X
crankshaft position input signal.

The injector voltage does not equal the ignition voltage
when the injector is commanded ªOFFº or the injector
voltage does not equal 0 volts when the injector is
commanded ªON.º

The above conditions are met for 15 seconds.
Action Taken When the DTC Sets

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

The PCM 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 P0204 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
An injector driver circuit that is open or shorted to voltage
will cause a DTC P0204 to set. It will also cause a misfire
due to an inoperative injector. A misfire DTC will also be
set indicating which cylinder is inoperative.
Long term and short term fuel trims that are excessively
high or low are a good indication that an injector is faulty.
Use Fuel Injector Coil Test Procedure to check for faulty
injectors.
Test Description
The number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. This step determines if DTC P0204 is the result of a
hard failure or an intermittent condition.
5. A special injector test connector is provided so that
the injectors can be electrically tested without
removal of the manifold. On the Trooper, the
special 7-way gray connector is located at the front
of the charcoal canister. The test connector can be
identified by the blue connector lock which is
tethered to the wiring harness. If the light for
cylinder 4 is ªONº steady before cranking the engine
as well as while cranking the engine, then the
injector driver circuit is shorted to ground.

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±181 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0204 ± Injector 4 Control Circuit

 
StepNo Ye s Value(s) Action
71. Disconnect the PCM connector for the affected
injectors.
2. With a test light connected to B+, probe the affected
injector driver circuit.
Does the test light illuminate?
ÐGo to Step 8Go to Step 15
8Repair short to ground in the injector driver circuit.
Is the action complete?
Ð
Go to OBD
System
Check
Ð
91. Disconnect the injector test connector.
2. At the injector side of the harness, connect an
ohmmeter between the positive wire (red with blue
tracer) and the wire for cylinder 4 (green/red).
Does the ohmmeter indicate continuity?
ÐGo to Step 11Go to Step 10
10Repair the open injector harness wire or open injector.
Is the action complete?
ÐVerify repairÐ
11At the PCM side of the injector test connector, check
the green/red wire for a short to voltage.
Was there a short to voltage?
ÐGo to Step 12Go to Step 13
12Repair the short to voltage.
Is the action complete?
ÐVerify repairÐ
13Check for an open circuit between the injector test
connector and the PCM.
Was there an open circuit?
ÐGo to Step 14Go to Step 15
14Repair the open circuit.
Is the action complete?
ÐVerify repairÐ
15Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ