troubleshooting engine ISUZU KB P190 2007 Workshop Owner's Manual

ENGINE DIAGNOSIS (C24SE) 6-13
Fuel Consumption Excessive
Condition Possible cause Correction
Trouble in fuel system Mixture too rich or too lean due to
trouble in fuel injection system Refer to "Abnormal Combustion"

Fuel cut function does not act Refer to "Abnormal Combustion"
Trouble in ignition system Misfiring or abnormal combustion
due to trouble in ignition system Refer to Hard Start or Abnormal
Combustion Troubleshooting
Guide
Others Engine idle speed too high Reset Idle Air Control Valve
Returning of accelerator control
sluggish Correct

Fuel system leakage Correct or replace
Clutch slipping Correct
Brake drag Correct
Selection of transmission gear
incorrect Caution operator of incorrect gear
selection
Oil Problems
Condition Possible cause Correction
Oil pressure too low Wrong oil in use Replace with correct engine oil
Relief valve sticking Replace
Oil pump not operating properly Correct or replace
Oil pump strainer clogged Clean or replace strainer
Oil pump worn Replace
Oil pressure gauge defective Correct or replace
Crankshaft bearing or connecting
rod bearing worn Replace
Oil contamination
Wrong oil in use Replace with new engine oil
Oil filter clogged Replace oil filter
Cylinder head gasket damage Replace gasket
Burned gases leaking Replace piston and piston rings or
rebore cylinders
Oil not reaching valve system Oil passage in cylinder head or cylinder body clogged Clean or correct

Engine Oil Pressure Check
1. Check for dirt, gasoline or water in the engine
oil.
a. Check the viscosity of the oil.
b. Change the oil if the viscosity is outside the specified standard.
c. Refer to the "Maintenance and Lubrication" section of this manual.
2. Check the engine oil level. The level should fall somewhere between the
"ADD" and the "FULL" marks on the oil level
dipstick.
If the oil level does not reach the "ADD" mark on
the oil level dipstick, engine oil must be added.
3. Remove the oil pressure unit.
4. Install an oil pressure gauge.
5. Start the engine and allow the engine to reach normal operating temperature (About 80 °C).
6. Measure the oil pressure.
Oil pressure should be:
150 kPa(21.8 psi) at idle speed.
7. Stop the engine.
8. Remove the oil pressure gauge
9. Install the oil pressure unit.
10. Start the engine and check for leaks.

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SECTION 6E
TABLE OF CONTENTS
C24SE ENGINE DRIVEABILITY AND EMISSIONS
ABBREVIATIONS CHARTS ......................... 6E-6
ECM Circuit Diagram (1/2) ............................ 6E-11
ECM Circuit Diagram (2/2) ............................ 6E-12
GROUND POINT CHART - LHD G.EXP (1/4) 6E-13
GROUND POINT CHART - RHD G.EXP (1/4) 6E-17
LOCATION ................................................... 6E-21
CABLE HARNESS & CONNECTOR LOCATION .............................................. 6E-23
CABLE HARNESS & CONNECTOR LOCATION - LHD ................................... 6E-24
CABLE HARNESS & CONNECTOR LOCATION - RHD ................................... 6E-25
CONNECTOR LIST ...................................... 6E-28
RELAY AND FUSE ....................................... 6E-30
RELAY AND FUSE BOX LOCATION (LHD & RHD) ........................................... 6E-30
FUSE AND RELAY LOCATION (LHD & RHD) 6E-32
ECM WIRING DIAGRAM (1/9) ..................... 6E-33
ECM WIRING DIAGRAM (2/9) ..................... 6E-34
ECM WIRING DIAGRAM (3/9) ..................... 6E-35
ECM WIRING DIAGRAM (4/9) ..................... 6E-36
ECM WIRING DIAGRAM (5/9) ..................... 6E-37
ECM WIRING DIAGRAM (6/9) ..................... 6E-38
ECM WIRING DIAGRAM (7/9) ..................... 6E-39
ECM WIRING DIAGRAM (8/9) ..................... 6E-40
ECM WIRING DIAGRAM (9/9) ..................... 6E-41
ECM CONNECTOR PIN ASSIGNMENT & OUTPUT SIGNAL .................................... 6E-42
GENERAL DESCRIPTION FOR ECM AND SENSORS ............................................... 6E-48
Engine Control Module (ECM) ................... 6E-48
Manifold Absolute Pressure (MAP) Sensor 6E-48
Throttle Position Sensor (TPS) .................. 6E-49
Idle Air Control (IAC) Valve ....................... 6E-49
Crankshaft Position (CKP) Sensor ............ 6E-50
Knock Sensor (KS) .................................... 6E-50
Engine Coolant Temperature (ECT) Sensor 6E-50
Intake Air Temperature (IAT) Sensor ........ 6E-51
Vehicle Speed Sensor (VSS) .................... 6E-51
Heated Oxygen (O
2) Sensor ..................... 6E-51
GENERAL DESCRIPTION FOR FUEL METERING .............................................. 6E-52 Battery Voltage Correction Mode ............... 6E-52
Clear Flood Mode ...................................... 6E-52
Deceleration Fuel Cutoff (DFCO) Mode .... 6E-52
Engine Speed/ Vehicle Speed/ Fuel Disable Mode ........................................................ 6E-52
Acceleration Mode ..................................... 6E-52
Fuel Cutoff Mode ....................................... 6E-52
Starting Mode ............................................ 6E-52
Run Mode .................................................. 6E-52
Fuel Metering System Components .......... 6E-53
Fuel Injector ............................................... 6E-53
Fuel Pressure Regulator ............................ 6E-53
Fuel Rail ..................................................... 6E-53
Fuel Pump Electrical Circuit ....................... 6E-53
Thottle Body Unit ....................................... 6E-53
GENERAL DESCRIPTION FOR ELECTRIC IGNITION SYSTEM ................................. 6E-54
Spark Plug ................................................. 6E-54
GENERAL DESCRIPTION FOR EVAPORATIVE EMISSION SYSTEM ............................... 6E-57
EVAP Emission Control System Purpose .. 6E-57
EVAP Emission Control System Operation 6E-57
System Fault Detection .............................. 6E-57
POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM .................................................. 6E-59
Crankcase Ventilation System Purpose .... 6E-59
A/C CLUTCH DIAGNOSIS ........................ 6E-60
A/C Clutch Circuit Operation ...................... 6E-60
A/C Clutch Circuit Purpose ........................ 6E-60
A/C Request Signal ................................... 6E-60
ISUZU STRATEGY BASED DIAGNOSTICS 6E-61
Overview .................................................... 6E-61
STRATEGY BASED DIAGNOSTICS CHART 6E-61 Diagnostic Thought Process ...................... 6E-62
1. Verify the Complaint .............................. 6E-62
2. Perform Preliminary Checks .................. 6E-62
3. Check Bulletins and Troubleshooting Hints 6E-63
4. Perform Service Manual Diagnostic Checks 6E-63
5a and 5b. Perform Service Manual Diagnostic Procedures .............................................. 6E-63
5c. Technician Self Diagnoses .................. 6E-63
5d. Intermittent Diagnosis .......................... 6E-64
6 E –1
E N GINE DRIV EABILITY AND E M IS SIONS

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ENGINE DRIVEABILITY AND EMISSIONS 6E–63
3. Check Bulletins and Troubleshooting Hints
NOTE: As estimated 30 percent of successful vehicle
repairs are diagnosed with this step!
What you should do
You should have enough information gained from
preliminary checks to accurately search for a bulletin
and other related service information. Some service
manual sections provide troubleshooting hints that
match symptoms with specific complaints.
What resources you should use
You should use the following resources for assistance in
checking for bulletins and troubleshooting hints:
• Printed bulletins
• Access ISUZU Bulletin Web site.
• Videotapes
• Service manual
4. Perform Service Manual Diagnostic Checks
What you should do
The “System Checks” in most service manual sections
and in most cells of section 8A (electrical) provide you
with:
• A systematic approach to narrowing down the possible causes of a system fault
• Direction to specific diagnostic procedures in the service manual
• Assistance to identify what systems work correctly
What resources you should use
Whenever possible, you should use the following
resources to perform service manual checks:
• Service manual
• Technical equipment (for viewing DTCs and analyzing data)
• Digital multimeter and circuit testing tools
• Other tools as needed
5a and 5b. Perform Service Manual Diagnostic Procedures
NOTE: An estimated 40 percent of successful vehicle
repairs are diagnosed with these steps!
What you should do
When directed by service manual diagnostic checks,
you must then carefully and accurately perform the
steps of diagnostic procedures to locate the fault related to the customer complaint.
What resources you should use
Whenever appropriate, you should use the following
resources to perform service manual diagnostic
procedures:
• Service manual
• Technical equipment (for analyzing diagnostic data)
• Digital multimeter and circuit testing tools
• Essential and special tools
5c. Technician Self Diagnoses
When there is no DTC stored and no matching
symptom for the condition identified in the service
manual, you must begin with a thorough understanding
of how the system(s) operates. Efficient use of the
service manual combined with you experience and a
good process of elimination will result in accurate
diagnosis of the condition.
What you should do
Step 1: Identify and understand the suspect
circuit(s)
Having completed steps 1 through 4 of the Strategy
Based Diagnostics chart, you should have enough
information to identify the system(s) or sub-system(s)
involved. Using the service manual, you should
determine and investigate the following circuit
characteristics:
• Electrical: – How is the circuit powered (power distributioncharts and/or fuse block details)?
– How is the circuit grounded (ground distribution charts)?
– How is the circuit controlled or sensed (theory of operation):
– If it is a switched circuit, is it normally open or normally closed?
– Is the power switched or is the ground switched?
– Is it a variable resistance circuit (ECT sensor or TP sensor, for example)?
– Is it a signal generating device (MAF sensor of VSS, for example)?
– Does it rely on some mechanical/vacuum device to operate?
•Physical:
– Where are the circuit components (componentlocators and wire harness routing diagrams):
– Are there areas where wires could be chafed or pinched (brackets or frames)?
– Are there areas subjected to extreme temperatures?

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ENGINE DRIVEABILITY AND EMISSIONS 6E–69
Reading Diagnostic Trouble Codes Using a
Te c h 2
The procedure for reading diagnostic trouble code(s) is
to used a diagnostic Tech 2. When reading DTC(s),
follow instructions supplied by Tech 2 manufacturer.
Clearing Diagnostic Trouble Codes
To clear Diagnostic Trouble Codes (DTCs), use the
Tech 2 “clear DTCs” or “clear information” function.
When clearing DTCs follow instructions supplied by the
Tech 2 manufacturer.
Diagnosis With Tech 2
If no codes are set:
•Refer to F1: Data Display and identify the electrical
faults that are not indicated by trouble code.
• Refer to “SYMPTOM DIAGNOSIS ”.
If codes are set: 1. Record all trouble codes displayed by Tech 2 and check id the codes are intermittent.
2. Clear the codes.
3. Drive the vehicle for a test to reproduce the faulty status.
4. Check trouble codes again using the Tech 2.
5. If no codes is displayed by test driving, the fault is intermittent. In this case, refer to “DIAGNOSIS
AIDS”.
6. If a code is present, refer to DTC Chart for diagnosis.
7. Check trouble codes again using the Tech 2.
Tech 2 CONNECTION
Tech 2 scan tool is used to electrically diagnose the
automatic transmission system and to check the
system. The Tech 2 enhances the diagnosis efficiency
though all the troubleshooting can be done without the
Te c h 2 . 1. Configuration of Tech 2
• Tech 2 scan tool kit (No. 7000086), Tech 2 scan tool (No. 7000057) and DLC cable (No.
3000095).
• SAE 16/19 adapter (No. 3000098) (3), RS232 loop back connector (No. 3000112) (2) and
PCMCIA card (No. 3000117) (1).
2. Tech 2 Connection
• Check the key switch is turn OFF.
• Insert the PCMCIA card (1) into the Tech 2 (5).
• Connect the SAE 16/19 adapter (3) to the DLC cable (4).
• Connect the DLC cable (4) to the Tech 2 (5).
• Connect the SAE 16/19 adapter (3) to the data link connector of the vehicle.
• Turn the key switch of the vehicle ON and press the “PWR” key of the Tech 2.
• Check the display of the Tech 2.
NOTE: Be sure to check that the power is not supplied
to the Tech 2 when attaching or removing the PCMCIA
card.

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ON-VEHICLE SERVICE (AW30–40LE) 7A3-13
Evaluation
i. If there is no 1→2 upshift:
• Solenoid S2 is stuck
• 1–2 shift valve is stuck
ii. If there is no 2 →3 upshift:
• Solenoid S1 is stuck
• 2–3 shift valve is stuck
iii. If there is no 3 →OD upshift (throttle valve opening
1/2):
• Solenoid S2 is stuck
• 3–OD shift valve is stuck
iv. If the shift point is defective: Refer to TROUBLESHOOTING CHART in this
section.
v. If the lock-up is defective: Refer to TROUBLESHOOTING CHART in this
section.
2. In the same manner, check the shock and slip at the 1→ 2, 2 →3 and 3 →OD upshifts.
NOTE: Drive the vehicle on level ground.
Evaluation
If the shock is excessive:
Refer to TROUBLESHOOTING CHART in this section. 3. Run at “D" position lock-up or OD gear and check fo
r
abnormal noise and vibration.
NOTE: The check for the cause of abnormal noise and
vibration must be made with extreme care as it could
also be due to loss of balance in the propeller shaft,
differential, the torque converter, etc. or insufficient
bending, rigidity, etc. in the power train.




RUW 37ASH000201

4. W hile running in “D" position, 2nd, 3rd gears and
OD, check to see that the possible kick-down
vehicle speed limits for 2 →1, 3 →1, 3 →2, OD →3
and OD →2 kick-downs conform to those indicated
on the automatic shift diagram.




RTW 77ASH003101
5. Check for abnormal shock and slip at kick-down.
6. W hile running in “D" position, OD gear or “lock-up", shift to “2" and “L" positions and check the engine
braking effect at each of these positions.


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