1998 ISUZU TROOPER stop start

6E±252
ENGINE DRIVEABILITY AND EMISSIONS
passage and on the IAC pintle, and excessive deposits
in the throttle bore and on the throttle plate.

Large vacuum leak ± Check for a condition that causes
a large vacuum leak, such as an incorrectly installed or
faulty PCV valve or a disconnected brake booster
hose.Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
DTC P1508 ± IAC System Low RPM

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Start the engine.
2. Turn all accessories ªOFFº(A/C, rear defroster,
etc).
3. Using a Tech 2, command RPM up to 1500, down to
500, and the up to 1500 while monitoring the
ªEngine Speedº on the Tech 2.
NOTE: This Tech 2 command may cause the engine to
ªcut outº when RPM goes above 1500. If this occurs,
the ªcutting outº will stop when the Tech 2 command for
the test is discontinued, or if the Tech 2 command is
changed to less than 1500 RPM.
Does the ªEngine Speedº remain within the specified
value of the ªDesired Idleº for each RPM command?
+ 50 RPM
No trouble
found. Go to
Diagnostic
Aids
Go to Step 3
31. Disconnect the IAC.
2. Install IAC Node Light 5-8840-2312-0 or equivalent.
3. With the engine running, command RPM up to
1500, down to 500, and then up to 1500 while
observing the node light.
NOTE: This Tech 2 command may cause the engine to
ªcut outº when RPM goes above 1500. If this occurs,
the ªcutting outº will stop when the Tech 2 command for
the test is discontinued, or if the Tech 2 command is
changed to less than 1500 RPM.
Does each node light cycle red and green (never
ªOFFº)?
ÐGo to Step 5Go to Step 4
41. Check the following circuits for an open, short to
voltage, short ground, or poor connections at the
PCM:

IAC ªAº Low.

IAC ªAº High.

IAC ªBº Low.

IAC ªBº High.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 8

6E±255 ENGINE DRIVEABILITY AND EMISSIONS

Throttle body ± Check for sticking throttle plate. Also
inspect the IAC passage for deposits or objects which
keep the IAC pintle from fully extending.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how oftenthe condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
DTC P1509 ± IAC System High RPM

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Start the engine.
2. Turn all accessories ªOFFº (A/C, rear defroster,
etc.).
3. Using a Tech 2, command RPM up to 1500, down to
500, and then up to 1500 while monitoring ªEngine
Speedº on the Tech 2.
NOTE: This Tech 2 command may cause the engine to
ªcut outº when RPM goes above 1500. If this occurs,
the ªcutting outº will stop when the Tech 2 command for
the test is discontinued, or if the Tech 2 command is
changed to less than 1500 RPM.
Does the ªEngine Speedº remain within the specified
value of ªDesired Idleº for each RPM command?
+ 50 RPM
No trouble
found. Go to
Diagnostic
Aids
Go to Step 3
31. Disconnect the IAC.
2. Install IAC Node Light 5-8840-2312-0 or equivalent.
3. With the engine running, command RPM up to
1500, down to 500, and then up to 1500 while
observing the node light.
NOTE: This Tech 2 command may cause the engine to
ªcut outº when RPM goes above 1500. If this occurs,
the ªcutting outº will stop when the Tech 2 command for
the test is discontinued, or if the Tech 2 command is
changed to less than 1500 RPM.
Does each node light cycle red and green (never
ªOFFº)?
ÐGo to Step 5Go to Step 4
41. Check the following circuits for an open, short to
voltage, short ground, or poor connections at the
PCM:

IAC ªAº Low

IAC ªAº High

IAC ªBº Low

IAC ªBº High
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
5Visually/physically inspect for following conditions:

Vacuum leaks.

Throttle plate or throttle shaft for binding.

Accelerator and cruise control cables for being
misadjusted or for binding.

Faulty, missing, or incorrectly installed PCV
valve.
Do any of the above require a repair?
Ð
Refer to
appropriate
section for
on-vehicle
service
Go to Step 6

00 Ð 2 SERVICE INFORMATION
TROUBLESHOOTING
CONTENTS
PAGE
Hard Starting ................................................................................................................... 00- 3
Starter Motor Inoperative ........................................................................................... 00- 3
Starter Motor Operates but Engine does not turn over ........................................... 00- 3
Engine turns over but does not start ......................................................................... 00- 4
Quick-on Start System (QOS III) ................................................................................. 00- 5
Unstable Idling ................................................................................................................. 00- 5
Insufficient Power ............................................................................................................ 00- 7
Excessive Fuel Consumption .......................................................................................... 00- 9
Excessive Oil Consumption ............................................................................................. 00- 9
Overheating ...................................................................................................................... 00-10
White Exhaust Smoke ..................................................................................................... 00-10
Dark Exhaust Smoke ........................................................................................................ 00-11
Oil Pressure Does Not Rise .............................................................................................. 00-11
Abnormal Engine Noise ................................................................................................... 00-12
Engine Knocking .......................................................................................................... 00-12
Gas Leakage noise ....................................................................................................... 00-12
Continuous noise ......................................................................................................... 00-12
Slapping noise .............................................................................................................. 00-13
Engine Cooling Trouble ................................................................................................... 00-14
Engine Electrical ............................................................................................................... 00-15
Starter does not run .................................................................................................... 00-15
Faulty Meshing or Pinion and Ring Gear ................................................................... 00-16
Magnetic Switch does not operate though starter switch is turned to ÒStart (ST)Ó ...00-17
Pinion Meshes with ring gear but engine does not run ........................................... 00-18
Starter does not stop though starter switch is returned to ÒONÓ .......................... 00-19

00 Ð 4 SERVICE INFORMATION
Checkpoint Possible cause Correction
Engine stop
mechanismDefective fuel cut solenoid valve Replace the fuel cut solenoid valve
3. ENGINE TURNS OVER BUT DOES NOT START
FUEL IS NOT BEING DELIVERED TO THE INJECTION PUMP
Fuel Fuel tank is empty Fill the fuel tank
Fuel piping Clogged or damaged fuel lines. Loose fuel
line connectionRepair or replace the fuel lines
Retighten the fuel line connection
Fuel filter Fuel filter overflow valve does not close Repair or replace the fuel filter
overflow valve
Clogged fuel filter element Replace the fuel filter element or
the filter cartridge
Fuel system Air in the fuel system Bleed the air from the fuel system
Fuel feed pump Defective feed pump Repair or replace the feed pump
FUEL IS BEING DELIVERED TO THE INJECTION PUMP
Fuel Use of the wrong fuel Use the correct fuel
Water particles in the fuel Carge the fuel
Fuel system Air in the injection pump Bleed the air from the fuel system
Injection nozzle Injection nozzle sticking Replace the injection nozzle
Injection nozzle injection starting pressure
too low
Improper spray conditionAdjust or replace the injection
nozzle
Injection pump Defective fuel injection nozzle resulting in
the fuel drippage after fuel injectionReplace the delivery valve
Defective injection pump control rack
operationRepair or replace the injection pump
control rack
Injection pump plunger worn or stuck Replace the injection pump plunger
assembley
Injection pump drive shaft seizure or other
damageReplace the injection drive shaft
Injection pump governor spring seizure Replace the injection pump
governor spring

SERVICE INFORMATION 00 Ð 19
STARTER DOES NOT STOP THOUGH STARTER
SWITCH IS RETURNED TO “ON”
YESNO
REPLACE STARTER SWITCHMAGNETIC SWITCH CONTACTS
ARE FUSED AND NOT MOVED, OR
A RETURN SPRING IS BROKEN OR
DETERIORATED
DISCONNECTED STARTER SWITCH WIRING CONNECTOR, AND CHECK STARTER SWITCH OPERATION.
THERE MUST BE NO CONTINUITY EXCEPT ABOVE LINES
KEY
POSITIONBATTERY
B1
LOCK
OFF
ACC
ON
START
IGNITION
IG1BATTERY
B2ACCESSORIES
ACCIGNITION
IG2STARTER
ST
REPLACE MAGNETIC SWITCH

6D2 Ð 2 STARTING SYSTEM
the plunger returns, the pinion is disengaged from ring
gear, and the armature stops rotation. When the engine
speed is higher than the pinion, the pinion idles, so that
the armature is not driven.
STARTING CIRCUIT

6D2 Ð 6 STARTING SYSTEM
DISASSEMBLY
1. Lead Wire Nut
·Loosen the nut on terminal ÒMÓ of magnetic
switch and disconnect the connector cable.
2. Bolt (2 pcs)
3. Magnetic Switch Assembly
10. Motor Assembly
11. Brush Holder
·Raise a brush spring to detach the negative side of
the brushes (2 pcs) from the commutator face and
remove the positive side of brushes (2pcs) from
the positive side of brushes (2pcs) from the brush
holder.
4. Torsion Spring
·Remove torsion spring from magnetic switch
assembly.
5. Plunger
6. Shim
7. Magnetic Switch
8. Through Bolt
9. Rear Cover
·Remove the through bolts, then remove the rear
cover.
12. Armature
13. Yoke Assembly
14. Bearing Retainer
15. Pinion Assembly
16. Bearing Holder
17. Bearing
18. Pinion Stopper Clip
·Remove the stopper clip using a screw driver o
equivalent.
19. Pinion Stopper
20. Return Spring
21. Pinion Shaft
22. Clutch
23. Dust Cover
24. Shift Lever
25. Gear Case

6D3 Ð 4 CHARGING SYSTEM
DIAGNOSIS
GENERAL ON-VEHICLE INSPECTION
The operating condition of charging system is indicated
by the charge warning lamp. The warning lamp comes on
when the starter switch is turned to ÒONÓ position. The
charging system operates normally if the lamp goes off
when the engine starts. If the warning lamp shows
abnormality or if undercharged or overcharged battery
condition is suspected, perform diagnosis by checking the
charging system as follows:
1. Check visually the belt and wiring connector.
2. With the engine in stop status, turn the starter switch
to ÒONÓ position and observe the warning lamp.
·If lamp does not come on:
Disconnect wiring connector from generator, an
ground the terminal ÒLÓ on connector side.
·If lamp comes on:
Repair or replace the generator.