1998 ISUZU TROOPER immobilizer

6E±52
ENGINE DRIVEABILITY AND EMISSIONS
10.This vehicle is equipped with a PCM which utilizes
an electrically erasable programmable read only
memory (EEPROM). When the PCM is replaced,
the new PCM must be programmed.
Refer to UBS
98 model year Immobilizer Workshop Manual.

6E±57 ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Control Circuit Diagnosis

 
StepNo Ye s Value(s) Action
19Replace the A/C switch.
Is the action complete?
ÐVerify repairÐ
20Use an ohmmeter to check continuity between the
electronic A/C thermostat and the blower switch.
Was there an open circuit?
ÐGo to Step 21Go to Step 22
21Repair the open wire (GRN/YEL) between the
thermostat and the blower switch.
Is the action complete?
ÐVerify repairÐ
22Replace the electronic A/C thermostat.
Is the an action complete?
ÐVerify repairÐ
23Check for an open circuit between A/C thermostat relay
and PCM A/C request terminal (E-15).
Was there an open circuit?
ÐGo to Step 24Go to Step 25
24Repair the open circuit between the PCM and A/C
thermostat relay.
Is the action complete?
ÐVerify repairÐ
25Check for an open circuit between the A/C switch (LT
GRN) and the A/C thermostat relay (LT GRN).
Was there an open circuit?
ÐGo to Step 26Go to Step 27
26Repair the open circuit between the A/C switch and the
A/C thermostat relay.
Is the action complete?
ÐVerify repairÐ
271. Ignition ªON.º
2. Use a DVM to check voltage at the A/C pressure
switch (BRN).
Was voltage equal to the specified value?
+BGo to Step 29Go to Step 28
28Repair the open circuit between the 10A A/C fuse and
the pressure switch.
Is the action complete?
ÐVerify repairÐ
29Use an ohmmeter to check continuity between the
pressure switch (GRN/WHT) and the A/C thermostat
relay (GRN/WHT).
Was the circuit open?
ÐGo to Step 30Go to Step 31
30Repair the open circuit between the pressure switch
and the A/C thermostat relay.
Is the action complete?
ÐVerify repairÐ
31Check for damaged pin or terminal at E-15 of the PCM.
Was a damaged pin or terminal found?
ÐGo to Step 32Go to Step 33
32Repair the damaged pin or terminal.
Is the action complete?
ÐVerify repairÐ
33Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±67 ENGINE DRIVEABILITY AND EMISSIONS
Multiple PCM Information Sensor DTCs Set

 
StepNo Ye s Value(s) Action
111. Disconnect the EGR valve.
2. Measure the voltage between the EGR pintle
position sensor signal circuit at the PCM harness
connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 13Go to Step 18
12Measure the voltage between the TFT sensor signal
circuit at the PCM harness connector and ground.
Does the voltage measure near the specified value?
0 VGo to Step 20Go to Step 19
13Replace the EGR valve.
Is the action complete?
ÐVerify repairÐ
14Locate and repair the short to voltage in the MAP
sensor signal circuit.
Is the action complete?
ÐVerify repairÐ
15Locate and repair the short to voltage in the TP sensor
signal circuit.
Is the action complete?
ÐVerify repairÐ
16Locate and repair the short to voltage in the IAT sensor
signal circuit.
Is the action complete?
ÐVerify repairÐ
17Locate and repair the short to voltage in the ECT
sensor signal circuit.
Is the action complete?
ÐVerify repairÐ
18Locate and repair the short to voltage in the EGR pintle
position sensor signal circuit.
Is the action complete?
ÐVerify repairÐ
19Locate and repair the short to voltage in the TFT sensor
signal circuit.
Is the action complete?
ÐVerify repairÐ
20Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?Ð
Go to OBD
System
Check
Ð

6E±75 ENGINE DRIVEABILITY AND EMISSIONS
17.This vehicle is equipped with a PCM which utilizes
an electrically erasable programmable read only
memory (EEPROM). When the PCM is replaced,
the new PCM must be programmed. Refer to
UBS
98 model year Immobilizer Workshop Manual.
No Malfunction Indicator Lamp (MIL)

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Attempt to start the engine.
Does the engine start?
ÐGo to Step 3Go to Step 6
3Check the meter fuse for the instrument cluster ignition
feed circuit.
Is the fuse OK?
ÐGo to Step 4Go to Step 16
4Ignition ªON,º probe the ignition feed circuit at the
cluster connector with a test light to ground.
Is the test light ªON?º
ÐGo to Step 5Go to Step 13
51. Ignition ªOFF.º
2. Disconnect the PCM.
3. Jumper the MIL driver circuit at the PCM connector
to ground.
4. Ignition ªON.º
Is the MIL ªON?º
ÐGo to Step 10Go to Step 11
6Check the PCM ignition feed and battery feed fuses (15
A engine fuse and 15 A PCM fuse).
Are both fuses OK?
ÐGo to Step 7Go to Step 15
71. Ignition ªOFF.º
2. Disconnect the PCM.
3. Ignition ªON.º
4. Probe the ignition feed circuit at the PCM harness
connector with a test light to ground.
Is the test light ªON?º
ÐGo to Step 8Go to Step 12
8Probe the battery feed circuit at the PCM harness
connector with a test light to ground.
Is the test light ªON?º
ÐGo to Step 9Go to Step 14
9Check for a faulty PCM ground connection.
Was a problem found?
ÐVerify repairGo to Step 10
10Check for damaged terminals at the PCM.
Was a problem found?
ÐVerify repairGo to Step 17
11Check for an open MIL driver circuit between the PCM
and the MIL.
Was a problem found?
ÐVerify repairGo to Step 18
12Substitute a known ªgoodº relay for the PCM main
relay.
Was the malfunction fixed?
ÐVerify repairGo to Step 13
13Repair the open in the ignition feed circuit.
Is the action complete?
ÐVerify repairÐ

6E±77 ENGINE DRIVEABILITY AND EMISSIONS
Malfunction Indicator Lamp (MIL) ªONº Steady
D06RW00007
Circuit description
The malfunction indicator lamp (MIL) should always be
illuminated and steady with ignition ªONº and the engine
stopped. Ignition feed voltage is supplied directly to the
MIL indicator. The powertrain control module (PCM)
turns the MIL ªONº by grounding the MIL driver circuit.
The MIL should not remain ªONº with the engine running
and no DTC(s) set. A steady MIL with the engine running
and no DTC(s) suggests a short to ground in the MIL
driver circuit.
Diagnostic Aids
An intermittent may be caused by a poor connection,
rubbed-through wire insulation, or a wire broken inside
the insulation. Check for the following items:

Poor connection or damaged harness ± Inspect the
PCM harness and connectors for improper mating,
broken locks, improperly formed or damaged
terminals, poor terminal-to-wire connection, and
damaged harness.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. If the MIL does not remain ªONº when the PCM is
disconnected, the MIL driver wiring is not faulty.
3. If the MIL driver circuit is OK, the instrument panel
cluster is faulty.
6. This vehicle is equipped with a PCM which utilizes
an electrically erasable programmable read only
memory (EEPROM). When the PCM is replaced,
the new PCM must be programmed. Refer to
UBS
98 model year Immobilizer Workshop Manual.

6E±78
ENGINE DRIVEABILITY AND EMISSIONS
Malfunction Indicator Lamp (MIL) ªONº Steady

StepActionValue(s)Ye sNo
1Was the ªOn-Board diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Ignition ªOFF,º disconnect PCM.
2. Ignition ªON,º observe the MIL (Service Engine
Soon lamp).
Is the MIL ªON?º
ÐGo to Step 3Go to Step 5
31. Ignition ªOFF,º disconnect the instrument panel
cluster.
2. Check the MIL driver circuit between the PCM and
the instrument panel cluster for a short to ground.
3. If a problem is found, repair as necessary.
Was the MIL driver circuit shorted to ground?
Ð
Go to OBD
System
Check
Go to Step 4
4Replace the instrument panel cluster.
Is the action complete?
Ð
Go to OBD
System
Check
Ð
51. Ignition ªOFF,º reconnect the PCM.
2. Using Tech 2, select ªOutput Miscellaneous Testº
and command the MIL ªOFF.º
Did the MIL turn ªOFF?º
Ð
Go to OBD
System
Check
Go to Step 6
6Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?Ð
Go to OBD
System
Check
Ð

6E±83 ENGINE DRIVEABILITY AND EMISSIONS
Engine Cranks But Will Not Run

 
StepNo Ye s Value(s) Action
201. At the PCM (female) side of the connector, connect
a test light between the ignition + terminal and one
of the injector driver circuits at the same connector.
2. Ignition ªON.º
3. Observe the test light, and repeat the test for each
injector driver circuit.
Did the test light stay on when checking any of the 6
injector driver circuits?
ÐGo to Step 21Go to Step 23
211. Ignition ªOFF,º disconnect the PCM.
2. Ignition ªON,º observe the test light.
Is the test light ªON?º
ÐGo to Step 22Go to Step 27
22Locate and repair the short to ground in the injector
driver circuit.
Is the action complete?
ÐVerify repairÐ
231. Using the same test location as in step 20, connect
a test light between the ignition terminal and one of
the driver circuits.
2. Crank the engine and observe the test light.
3. Repeat for each injector driver circuit.
Did the light blink during the test for each circuit?
ÐGo to Step 25Go to Step 24
24Check for an open injector driver circuit.
Was a problem found?
ÐVerify repairGo to Step 27
251. At the injector (male) side of the gray connector,
connect an ohmmeter between the ignition pin and
one of the driver circuit pins.
2. Check for continuity in the circuit.
3. Repeat for each injector circuit. The readings
should be approximately equal to the specified
value for injector resistance.
Was a problem found?
12.5 ohmsVerify repairGo to Step 8
26Repair the ignition feed circuit.
Is the action complete?
ÐVerify repairÐ
27Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ
281. Raise the vehicle and disconnect the CKP sensor
harness.
2. Ignition ªON.º
3. With a test light to ground, probe the harness
ignition feed terminal.
Did the light illuminate?
ÐGo to Step 30Go to Step 29
29Check the ignition feed wire between the sensor and
the PCM for a short to ground or open circuit.
Is the action complete?
ÐVerify repairÐ

6E±87 ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Electrical Test

 
StepNo Ye s Value(s) Action
9Check for short or open between the PCM and the fuel
pump relay.
Was a problem found?
ÐVerify repairGo to Step 10
101. Check the fuel pump relay circuit for a poor terminal
connection at the PCM.
2. If a problem is found, replace terminal as necessary.
Was a problem found?
ÐVerify repairGo to Step 11
11Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ
121. Reconnect the fuel pump relay.
2. Disconnect the fuel pump electrical connector at the
fuel tank.
3. Using a test light connected to ground, probe the
fuel pump feed wire (harness side).
4. Command the fuel pump ªONº with Tech 2.
Did the light illuminate for 2 seconds?
ÐGo to Step 15Go to Step 13
131. Honk the horn to verify that the horn relay is
functioning.
2. Substitute the horn relay for the fuel pump relay.
3. Leave the test light connected as in step 12.
4. Command the fuel pump ªONº with Tech 2.
Did the test light illuminate for 2 seconds when the fuel
pump was commanded ªON?º
ÐGo to Step 17Go to Step 14
141. Re-connect the horn relay in its proper location.
2. Check for a short circuit, blown fuse or open circuit
between the relay and the fuel tank.
Is the action complete?
ÐVerify repairÐ
151. With the fuel pump electrical connector at the fuel
tank disconnected, connect a test light between the
feed wire and the ground wire (harness side).
2. Command the fuel pump ªONº with Tech 2.
Did the test light illuminate for 2 seconds?
ÐGo to Step 18Go to Step 16
16Repair the open circuit in the fuel pump ground wire.
Is the action complete?
ÐVerify repairÐ
171. Re-connect the horn relay in its proper location.
2. Replace the fuel pump relay.
Is the action complete?
ÐVerify repairÐ
18Replace the fuel pump.
Is the action complete?
ÐVerify repairÐ