start ISUZU KB P190 2007 Workshop Repair Manual

Engine Management – V6 – General Information Page 6C1-1–25

Engine Oil Level Sensor
The engine oil level sensor is comprised of a magnetic reed
switch (1) contained within the sensor, a float (2) and a
magnetic pin (3). The magnetic reed switch is a normally
open switch, which closes when a magnet field is present.
W hen the engine oil level is within specifications, the pin on
the inside of the float is pushed up against the reed switch
(view A). W hen the oil level drops and the magnetic pin
moves away from the reed switch (view B), the switch
contacts opens.
The ECM provides a 5 V reference signal to the engine oil
temperature sensor and monitors the return signal. The
ECM only monitors the oil level signal prior to engine start-
up, and once the engine is cranking, the ECM disregards
the oil level sensor signal.
Figure 6C1-1 – 26
4.11 Engine Oil Pressure Sensor
The engine oil pressure (EOP) sensor measures engine oil
pressure. W hen the EOP sensor signal is below a certain
value, the ECM sends a serial data message to the
powertrain interface module (PIM) requesting the PIM to
turn on the engine oil pressure warning lamp.


Figure 6C1-1 – 27

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Engine Management – V6 – Diagnostics Page 6C1-2–1

6C1-2 Engine Management – V6
Diagnostics
ATTENTION
Before performing any service operation or other procedure described in this Section, refer to 1.5 Warning
Caution and Notes for correct workshop practices with regard to safety and/or property damage.
1 General Information ............................................................................................................ ...................4
1.1 Diagnostic System Check ..................................................................................................................................... 4
1.2 Diagnostic Trouble Code Tables ................................................................................................. ......................... 4
1.3 Symptoms Diagnostics ......................................................................................................................................... 5
1.4 Diagnostic Trouble Codes .................................................................................................................................... 5
1.5 Warning Caution and Notes .................................................................................................................................. 6
2 GM LAN Serial Communication Circuit ............................................................................................ ....8
3 Wiring Diagrams and Connector Charts ........................................................................................... ...9
3.1 Wiring Diagrams .................................................................................................................................................... 9
3.2 ECM Connector End Views ................................................................................................................................. 12
3.2 Engine Control Connector End Views ............................................................................................. .................. 16
4 Diagnostics Starting Point...................................................................................................................18
4.1 Basic Requirements ............................................................................................................................................ 18
4.2 Diagnostic Precautions ......................................................................................................... .............................. 18
4.3 Preliminary Checks.............................................................................................................................................. 19
4.4 Diagnostic System Check ........................................................................................................ ........................... 20
5 Symptoms Diagnostics ........................................................................................................................22
5.1 Symptoms Diagnosis Table ....................................................................................................... ......................... 22
5.2 Intermittent Fault Conditions .............................................................................................................................. 22
5.3 Backfire................................................................................................................................................................. 24
5.4 Cranks But Does Not Run ........................................................................................................ ........................... 26
5.5 Cuts Out, Misses.................................................................................................................................................. 27
5.6 Detonation / Spark Knock ....................................................................................................... ............................ 28
5.7 Dieseling, Run-on ................................................................................................................................................ 28
5.8 Hard Start ............................................................................................................................................................. 29
5.9 Hesitation, Sag and Stumble .................................................................................................... .......................... 30
5.10 Lack of Power, Sluggishness or Sponginess ...................................................................................... ............. 31
5.11 Poor Fuel Economy ............................................................................................................................................. 32
5.12 Rough, Unstable, Incorrect Idle or Stalling .................................................................................... ................... 34
5.13 Surges / Chuggles ............................................................................................................................................... 35
6 Functional Checks................................................................................................................................37
6.1 General Information ............................................................................................................ ................................. 37
6.2 Fuel Injector Coil Test ......................................................................................................................................... 37
6.3 Fuel Injector Balance Test ..................................................................................................... ............................. 42
6.4 Fuel Injector Leak Down Test ................................................................................................... .......................... 44
6.5 Alcohol / Contaminants in Fuel Diagnosis ....................................................................................... ................. 46
6.6 Crankshaft Position (CKP) System Variation Learn Procedure..................................................................... .. 46
6.7 Throttle Body Relearn.......................................................................................................................................... 47

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Engine Management – V6 – Diagnostics Page 6C1-2–4

1 General Information
1.1 Diagnostic System Check
The engine management diagnostic procedure is organised in a logical structure that begins with the Diagnostic System
Check. The Diagnostic System Check directs the diagnostic procedure to the logical steps necessary to diagnose an
engine driveability fault condition.
1.2 Diagnostic Trouble Code Tables
The Diagnostic System Check directs the diagnostic procedure to the appropriate diagnostic trouble code (DTC) tables
if there is a DTC currently stored in the engine control module (ECM).
The diagnostic tables locate a faulty circuit or component through a logic based on the process of elimination. These
diagnostic tables are developed with the following assumptions:
• the vehicle functioned correctly at the time of assembly,
• there are no multiple faults, and
• the problem currently exists.
Understanding and the correct use of the diagnostic tables are essential to reduce diagnostic time and to prevent
misdiagnosis.
Multiple DTC Fault Conditions
Some fault conditions trigger multiple component DTCs even if the fault condition exists only on a single component. If
there are multiple DTCs stored in the ECM, the service technician must view and record all DTCs logged.
The relationship between the logged DTCs can then be analysed to determine the source of the fault condition. Always
begin the diagnostic process with the DTC table of the fault condition that may trigger other DTCs to set.
The following fault conditions may trigger multiple DTCs:
• a fault in the serial data communication circuit,
• a system voltage that is too low may cause incorrect engine management system operation or engine
management component malfunction,
• a system voltage that is too high may damage the ECM and/or other engine management components,
• fault condition in the ECM read only memory (ROM) or random access memory (RAM),
• fault condition in the ECM internal circuitry or programming,
• improperly connected sensor or component wiring connector, or
• an electrical fault condition in the following shared ECM electrical circuits trigger DTCs on components or sensors
that share in the faulty shared circuit. Test the electrical circuit of the appropriate sensors or components to isolate
the fault condition. Refer to 3 W iring Diagrams and Connector Charts in this Section.
• 5 V Reference Circuit,
• Low Reference Circuit, or
• Ignition Control Voltage Circuit.
If there are no obvious faults to begin a multiple DTC fault condition diagnostic procedure, diagnose the DTCs in the
following order unless directed otherwise:
1 Always start with the lowest numbered component level DTCs such as:
• sensor DTCs,
• solenoid DTCs, or
• relay DTCs.
2 Then follow with system level DTCs such as:
• misfire DTCs,

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Engine Management – V6 – Diagnostics Page 6C1-2–15

C-56–28 Not Used
C-56–29 V HI_SIG_3 B1S2 O2 Sensor High Signal (Bank 1 Sensor 2)
C-56–30 Not Used
C-56–31 R/W CRANK_REQ Crank Voltage
C-56–32 B PRKNEU Park/Neutral Switch Signal
C-56–33 Not Used
C-56–34 Not Used
C-56–35 Y START_RLY Starter Relay Coil Control
C-56–36 BR/R BATT + Battery Positive Voltage
C-56–37 Not Used
C-56–38 PU SDI Data Link Connector (DLC) Serial Data
C-56–39 R 5VDC1 5 Volt Reference 1
C-56–40 BR 5VGD5 Low Reference – Ground 5
C-56–41 P RTN_4 B2S2 O2 Sensor Low Signal (Bank 2 Sensor 2)
C-56–42 Y/R FUEL_LVL1 Fuel Level Sensor Signal
C-56–43 Y MAF MAF Sensor Signal
C-56–44 Y PED_POS_2 APP Sensor 2 Signal
C-56–45 Not Used
C-56–46 GR/R CRU_ETC_TCC Brake Switch (S220 – ‘C’) Cruise Cancel Signal
C-56–47 Not Used
C-56–48 Not Used
C-56–49 GR/R AC_CLU A/C Compressor Clutch Relay Control
C-56–50 BR/Y MIL Malfunction indicator Lamp
C-56–51 Not Used
C-56–52 Not Used
C-56–53 BR CRCTL_CLU_SW Clutch Switch (S42) Cruise Cancel Signal
C-56–54 Not Used
C-56–55 R/G CAN_LO_2 GMLAN Serial Data Bus – Low
C-56–56 BR/Y 5VDC3 5 Volt Reference 3
C-56–57 BR/R RTN_3 B1S2 O2 Sensor Low Signal (Bank 1 Sensor 2)
C-56–58 R/Y ACC Accessory Voltage
C-56–59 Not Used
C-56–60 L PED_POS_1 APP Sensor 1 Signal
C-56–61 V HI_SIG_4 B2S2 O2 Sensor High Signal (Bank 2 Sensor 2)
C-56–62 Not Used
C-56–63 Not Used
C-56–64 Not Used

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Engine Management – V6 – Diagnostics Page 6C1-2–18

4 Diagnostics Starting Point
4.1 Basic Requirements
Basic Knowledge Required

A lack of basic understanding regarding
electronics, electrical wiring circuits and use
of electrical circuit testing tools when
performing an engine management system
diagnostic procedure could result in incorrect
diagnostic results or damage to engine
management system components.
Understanding of the following is required to perform the diagnostic procedures detailed in this Section. Refer to 8A
Electrical - Body and Chassis and to Basic Tools Required.
• Basic electronics,
• Electrical wiring circuits,
• Electrical circuits testing, and
• Correct use of the basic engine management system diagnostic tools.
In addition, understanding of the engine management system is essential to prevent misdiagnosis and component
damage. Refer to 6C1-1 Engine Management – V6 – General Information.
Basic Tools Required

Use of incorrect electrical circuit diagnostic
tools when performing the Engine
Management diagnostic procedures could
result in incorrect diagnostic results or
damage to engine management system
components.
The following electrical circuit testing tools are required to perform the diagnostic procedures detailed in this Section.
• Tech 2,
• Test lamp, refer to 8A Electrical - Body and Chassis, and
• Digital multimeter with 10 M Ω impedance, refer to 8A Electrical - Body and Chassis.
4.2 Diagnostic Precautions
The following precautions must be observed when performing the powertrain diagnostic procedure, otherwise incorrect
diagnostic results or damage to engine management system components will occur:
• Disconnection of the battery affects certain vehicle electronic systems. Refer to 6D1-3 Battery – V6 before
disconnecting the battery.
• Disconnect the battery negative lead when performing the following procedures:
− Disconnecting the ECM connectors, or
− Charging the battery.
• Disconnect the battery terminal lead and the ECM connectors before attempting any electric arc welding on the
vehicle.

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Engine Management – V6 – Diagnostics Page 6C1-2–19

• Do not start the engine if the battery terminal is not properly secured to the battery.
• Do not disconnect or reconnect the following while the ignition is switched on or when the engine is running:
− Any engine management system component electrical wiring connector, or
− Battery terminal leads.
• Ensure the correct procedure for disconnecting and connecting engine management system electrical wiring
connectors is always followed. For information on the correct procedure for disconnecting and connecting specific
wiring connectors, refer to 6C1-3 Engine Management – V6 – Service Operations.
• Ensure that all wiring harness connectors are fitted correctly.
• W hen steam or pressure cleaning engines, do not direct the cleaning nozzle at engine management system
components.
• Do not clear any DTCs unless instructed.
• The fault must be present when using the diagnostic trouble code (DTC) diagnostic tables. Otherwise,
misdiagnosis or replacement of good parts may occur.
• Do not touch the ECM connector pins or soldered components on the ECM circuit board to prevent ECM
Electrostatic Discharge damage. Refer to 8A Electrical - Body and Chassis for information on Electrostatic
Discharge.
• Use only the test equipment specified in the diagnostic tables as other test equipment may give incorrect results or
damage good components.
• The ECM is designed to withstand normal current draw associated with vehicle operations. However, the following
fault conditions or incorrect test procedure may overload the ECM internal circuit and damage the ECM:
− A short to voltage fault condition in any of the ECM low reference circuits may cause internal ECM and / or
sensor damage. Therefore, any short to voltage fault condition in the ECM low reference circuits must be
rectified before replacing a faulty component.
− A short to ground fault condition in any of the ECM 5 V reference circuits may cause internal ECM and / or
sensor damage. Therefore, any short to ground fault condition in the ECM 5 V reference circuits must be
rectified before replacing a faulty component.
− W hen using a test lamp to test an electrical circuit, do not use any of the ECM low reference circuits or 5 V
reference circuits as a reference point. Otherwise, excessive current draw from the test lamp may damage
the ECM.
• Disregard DTCs that set while performing the following diagnostic Steps:
− Using Tech 2 actuator tests, or
− Disconnecting an engine management system sensor connector then switching on the ignition.
• After completing the required diagnostics and service operations, road test the vehicle to ensure correct engine
management system operation.
4.3 Preliminary Checks
The preliminary checks are a set of visual and physical checks or inspections that may quickly identify engine
management system fault condition.
• Refer to the appropriate Service Techlines for relevant information regarding the fault condition.
• Ensure the battery is fully charged.
• Inspect the battery connections for corrosion or a loose terminal.
• Ensure that all engine management system related fuses are serviceable.
• Inspect for incorrect aftermarket theft deterrent devices, lights or mobile phone installation.
• Ensure there is no speaker magnet positioned too close to any electronic module that contains relays.
• Inspect the engine wiring harness for proper connections, pinches or cuts.
• Ensure that all engine management related electrical wiring connectors are fitted correctly.
• Inspect the ECM ground connections for corrosion, loose terminal or incorrect position.

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Engine Management – V6 – Diagnostics Page 6C1-2–22

5 Symptoms Diagnostics
5.1 Symptoms Diagnosis Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2 Refer to
4.4 Diagnostic System Check
2 Is the fault intermittent? Refer to
5.2 Intermittent Fault Conditions Go to Step 3
3
Does the engine backfire? Refer to
5.3 Backfire Go to Step 4
4
Does the engine crank but does not run? Refer to
5.4 Cranks But Does Not Run Go to Step 5
5
Does the engine cut-out or miss? Refer to
5.5 Cuts Out, Misses Go to Step 6
6
Is there a detonation or spark knock noise coming from the engine? Refer to
5.6 Detonation / Spark Knock Go to Step 7
7
Is there an engine dieseling or run-on condition? Refer to
5.7 Dieseling, Run-on Go to Step 8
8
Is there an engine hard starting condition? Refer to
5.8 Hard Start Go to Step 9
9
Is there an engine hesitation, sag or stumble condition? Refer to
5.9 Hesitation,
Sag and Stumble Go to Step 10
10
Does the engine suffer from lack of power, sluggishness or
sponginess? Refer to
5.10 Lack of Power, Sluggishness or Sponginess Go to Step 11
11
Does the engine suffer from poor fuel economy? Refer to
5.11 Poor Fuel Economy Go to Step 12
12
Does the engine suffer from rough, unstable or incorrect idle and
engine stalling? Refer to
5.12 Rough,
Unstable, Incorrect Idle or Stalling Go to Step 13
13
Does the engine surge or chuggle? Refer to
5.13 Surges / Chuggles Go to Step 14
When all diagnosis and repairs are completed, check the system for correct operation.
5.2 Intermittent Fault Conditions
Description
A fault condition is intermittent if one of the following conditions exists:
• the fault condition is not always present,
• the fault condition cannot be presently duplicated, or

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Engine Management – V6 – Diagnostics Page 6C1-2–23

• there is no Current DTC but a History DTC is stored.
Diagnostic Table
Checks Actions
Preliminary
• Perform the preliminary checks. Refer to 4.3 Preliminary Checks in this
Section.
• Gather information from the customer regarding the conditions that trigger the
intermittent fault such as:
• At what engine or ambient temperature range does the fault occur?
• Does the fault occur when operating aftermarket electrical equipment inside
the vehicle?
• Does the fault occur on rough roads or in wet road conditions?
• If the intermittent fault is a start and then stall condition, check the immobiliser
system. Refer to 11A Immobiliser.
Tech 2 Tests The following are lists of Tech 2 diagnostic tests that may be used to diagnose
intermittent faults:
• W riggle test the suspected wiring harness and connectors while observing Tech 2
operating parameters. If Tech 2 read-out fluctuates during this procedure, check
the tested wiring harness circuit for a loose connection.
• Observe the freeze frame / failure records for the suspected history DTC and then
operate the vehicle in the conditions that triggers the intermittent fault while an
assistant observes the suspected Tech 2 operating parameter data.
• Capture and store data in the snapshot mode when the fault occurs. The stored
data may be played back at a slower rate to aid diagnostics. Refer to Tech 2 User
Instructions for further information on the Snapshot function.
• Compare the engine operating parameters of the engine being diagnosed to the
engine operating parameters of a known good engine.
Malfunction Indicator Lamp The following conditions may cause an intermittent Malfunction Indicator Lamp fault with no DTC listed:
• Electromagnetic interference (EMI) caused by a faulty relay, ECM controlled
solenoid, switch or other external source.
• Incorrect installation of aftermarket electrical equipment such as the following:
• mobile phones,
• lights, or
• radio equipment.
• ECM grounds are loose.

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Engine Management – V6 – Diagnostics Page 6C1-2–24

Checks Actions
Temperature Related Temperature related intermittent fault condition occurs only when the engine or ambient
temperature is hot, or only when it is cold.
• If the intermittent fault is heat related, review Tech 2 data in relationship to the
following:
• high ambient temperature,
• engine generated heat,
• circuit generated heat due to a poor electrical connection or high electrical
load, and
• higher than normal load conditions (towing, etc.).
• If the intermittent fault is related to cold ambient or engine temperature, review
Tech 2 data in relationship to the following:
• low ambient temperature, and
• the fault condition that occurs only on a cold start situation.
Additional Tests
• Incorrect installation of aftermarket electrical equipment such as the following:
• mobile phones,
• theft deterrent alarms,
• lights, or
• radio equipment.
• Electromagnetic interference (EMI) caused by a faulty relay, ECM controlled
solenoid or switch. The fault is triggered when the relay or solenoid is activated.
• Test the A/C compressor clutch and some relays that contain a clamping diode or
resistor for an open circuit.
• Test the generator for a faulty rectifier bridge that may allow the A/C noise into the
ECM electrical circuit.
When all diagnosis and repairs are completed, check the system for correct operation.
5.3 Backfire
Description
The air / fuel mixture in the intake manifold or in the exhaust system ignites which produces a loud popping noise.
Checks Actions
Preliminary Perform the Preliminary Checks. Refer to 4.3 Preliminary Checks in this
Section.
Sensor / System • Check the air intake system and crankcase for air leaks.
• Check the PCV System for correct operation. Refer to 6A1 Engine Mechanical –
V6.
• Use Tech 2 to monitor the knock sensor system for excessive spark retard
activity. Check for items that cause spark retard activity.

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Engine Management – V6 – Diagnostics Page 6C1-2–25

Checks Actions
Fuel System
• Check the fuel system for the following fault conditions. Refer to 6C Fuel System
– V6 – V6.
• restricted fuel filter,
• incorrect fuel pressure, and
• contaminated fuel.
• Check the operation of the fuel injectors. Refer to 6C1-3 Engine Management –
V6 – Service Operations.
• Perform the fuel injector balance test, refer to 6.3 Fuel Injector Balance
Test in this Section.
• Check the items that can cause an engine to run lean.
• Check the items that cause an engine to run rich.
Ignition System
• Check for an intermittent ignition circuit malfunction.
• Inspect for moisture or corrosion around the spark plug / ignition coil area.
• Test the ignition coil voltage output. Refer to 6C1-3 Engine Management – V6 –
Service Operations.
• Remove and inspect the spark plugs. Refer to 6C1-3 Engine Management – V6 –
Service Operations.
NOTE
If the spark plugs are fouled, determine the cause of the fouling before
replacing the spark plugs. Refer to 6C1-3 Engine Management – V6 –
Service Operations.
• Check for loose ignition coil ground circuit.
Engine Cooling System Check the engine for over-heating. Refer to 6B1 Engine Cooling – V6.
Engine Mechanical Check for the following engine fault conditions. Refer to 6A1 Engine Mechanical – V6.
• low compression, and
• worn valve train components.
Additional Checks
• Check the exhaust system for possible restrictions. Refer to 6F Exhaust System –
V6.
• Electromagnetic interference (EMI) on the crankshaft position (CKP) sensor can
cause an engine misfire condition.
Using Tech 2, monitor the engine speed parameter. A sudden increase in the engine speed parameters without moving the throttle position indicates that an
Electromagnetic Interference fault may be present.
W iring harness routing which may be positioned very close to a high voltage or high current device such as the following may induce EMI:
• secondary ignition components, or
• motors and generators.
Dirty starter motor commutator or brushes can mask the crankshaft position sensor signal.
• Check the torque converter clutch (TCC) operation. A TCC that applies too soon
can cause engine detonation, which will trigger spark retard activity. Refer to 7C1
Automatic Transmission – 4L60E – General Information.
When all diagnosis and repairs are completed, check the system for correct operation.

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