PDF Troubleshooting Manual Isuzu 4HK1 & 6HK1 Diesel Engine - 3 MB
Quickly diagnose and resolve issues with your Isuzu 4HK1 or 6HK1 diesel engine using this specialized troubleshooting manual.
This guide provides systematic diagnostic procedures, fault codes, and symptom-based charts to help you pinpoint problems accurately.
It's an invaluable tool for mechanics to reduce diagnostic time and perform effective repairs.
Get your engine back in service faster with this expert guide.
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--- Page 1 ---
Introduction
This Troubleshooting Manual describes the structure and the troubleshooting of
electronic control fuel injection system (common rail type) in 4HK1 and 6HK1
industrial engines.
Use this manual sufficiently to perform service work properly and quickly.
Isuzu Motors Limited
Off-highway Powertrain
Operation Dept.
--- Page 3 ---
4/6HK1 Electronic Control Fuel Injection System (Common Rail Type) 1E-9
How to read trouble diagnosis section
The following illustration is an example for trouble diagnosis section. See this illustration and description.
DTC: P0192 (Flash code 245) Common rail pressure sensor fault (low voltage fault, short Action taken when DTC is set Improper connection of harness connector
circuit) 1 2 3 4 Trouble is displayed on the monitor of the Defective harness routing
machine* or diagnosis lamp comes on. (* Nothing Worn harness cladding
10
is displayed depending on the machine manufac- Wire disconnection inside harness cladding
turer) Following inspections are necessary to detect these
causes.
Engine control Back-up mode
module (ECM) Improper connection of harness connector and
Rail pressure feedback control stopped ECM connector
CMP sensor
signal
Common rail pressure
sensor signal
5V
EGR position
sensor signal
EGR position
sensor signal
EGR position
sensor signal
11
Limited injection amount 2 (multi-injection stopped) Poor connection of terminal from connector
EGR stopped Unmatched terminals are fitted.
B+ B+ B+ Switches the control to SCV compulsory drive Damage of connector lock
80 MPa target Poor contact between terminal and wire
99 E-56 98 E-56 100 E-56 101 E-56 82 E-56 90 E-56 87 E-56 92 E-56 110 E-56 93 E-56 103 E-56 94 E-56 111 E-56 Damaged harness
Recovery from failure
Visually check the harness for damage.
Refer to 1E-310, List of Diagnostic Trouble Codes Check the relevant items on the scan tool data
recovery from failure. 12
and About recovery from failure in this section for display while moving the connector and the har-
ness which are related to the sensor. The varia-
3 H-8 7 H-8 2 H-8 6 H-8 1 H-8 5 H-8
tion of the display indicates the faulty part.
4 H-20 5 H-20 6 H-20 14 H-20 13 H-20 12 H-20 The conditions to clear the MIL/DTC
5 The present trouble turns to history trouble when
the condition is out of the range from DTC set con-
Test description
Numbers below indicate step numbers in the chart.
0.75
W/R
0.75
B/W
0.75
Br 0.75 0.75 0.75 0.75 0.75 0.75 0.75 0.75
dition (recovery from failure). 3. In case of present trouble, the Common rail pres-
W G/Y W/L G/W W/B G/B W/R B
The diagnosis lamp will go off after the code turns sure sensor displays more than the specified value. In
to history trouble and the key switch is turned this case, identify the cause by referring to Diagnostic
0.75 0.75 0.75 0.75
1 E-80 2 E-80 6 E-80 3 E-80 7 E-80 4 E-80 8 E-80 5 E-80 OFF then ON again. aid .
Br B G W
Using the scan tool, or memory clear switch and 5. If the Common rail pressure sensor displays more
diagnostic switch operation enables to clear DTCs. than the specified value when the common rail pres-
sure sensor connector is removed, the circuit beyond
1 E-1122 E-112 3 E-112 1 E-113 2 E-113 3 E-113 V
Diagnostic aid the sensor is normal including ECM.
W
EGR position sensor/EGR motor
U
be the cause. 13
If the intermittent trouble is suspected, followings may
EGR valve
Step Action Value YES NO
CMP sensor Common rail pressure sensor Perform the OBD system check. Perform the OBD
1 system check and
Is the procedure completed? Go to Step 2. Go to Step 2.
TSHK0028 2 Is the scan tool (KW communication) available? Go to Step 3. Go to Step 14.
Check the value for common rail pressure sensor
Description of circuit Main trouble symptom using scan tool.
The common rail pressure sensor detects the common Engine stall possible 1. Connect the scan tool.
rail internal pressure. The common rail pressure sensor
is installed to the common rail. As the common rail
Output lowering 7 3
2. Start the engine.
0.7 V (at idle)
3. Check the value for Common rail pressure
internal pressure changes depending on engine condi- Preconditions when DTC is set sensor using scan tool.
tion, output voltage of the common rail pressure sensor
6
will change (if the common rail internal fuel pressure is
low, output voltage becomes low, if the pressure is
8
Key switch input voltage is 18V or more.
DTC P1630 or P1635 is not detected.
Is the Common rail pressure sensor output volt-
age less than the specified value? Go to Step 4.
Go to Diagnostic
aid .
high, the output voltage becomes high as well). The Check for installation condition of the common rail
engine control module (ECM) reads this output voltage DTC set condition pressure sensor, ECM and coupling connector.
change, converting it into common rail internal pres-
sure, to utilize for control. Dedicated communication 0.7V or less.
9
Common rail pressure sensor voltage becomes
4
1.
2.
Check for play or looseness in the connection.
If the trouble is detected, repair or replace as
circuits are used for the sensor power supply (5V), SIG, required.
and ground in the common rail pressure sensor, which
are connected to the ECM. Also, the sensor circuit is Is the trouble detected? Go to Step 12. Go to Step 5.
shielded to avoid electrical noise etc.
Step Action Value YES NO About common rail pressure sensor Breaker box inspection procedure
1. Turn the key switch to OFF . Perform the inspection in the following procedure if
2. Disconnect the common rail pressure sensor there is such an instruction to use breaker box in the
connector. step. After inspection, return to the diagnostic step.
3. Turn the key switch to ON .
5 0V
4. Check the value for Common rail pressure
sensor using scan tool.
Is the Common rail pressure sensor output volt-
age specified value? Go to Step 8. Go to Step 6.
1. Check for followings in the power supply circuit
between ECM and common rail pressure sen-
sor using breaker box or DMM. 3 2 1
Refer to 1E-427, Breaker box inspection pro-
cedure, DTC: P0192 (Flash code 245) Com-
mon rail pressure sensor fault (low voltage
14
fault, short circuit), List of Diagnostic Trouble
Codes .
Note:
If breaker box is not available, refer to 1E-428, TSWG0055
6 On-board check procedure for sensors, DTC: Name
P0192 (Flash code 245) Common rail pressure 1. GND
sensor fault (low voltage fault, short circuit), List of 2. Signal
Diagnostic Trouble Codes . 3. Power supply Name
Open circuit 1. Breaker box
High resistance 2. DMM
Characteristics of common rail pressure
2. If the trouble is detected, repair or replace as
required.
sensor
Is the trouble detected? Go to Step 12. Go to Step 7.
1. Check for followings in the signal circuit
(V)
between ECM and common rail pressure sen-
4.2
sor using breaker box or DMM.
Refer to 1E-427, Breaker box inspection pro-
cedure, DTC: P0192 (Flash code 245) Com-
mon rail pressure sensor fault (low voltage
fault, short circuit), List of Diagnostic Trouble
Codes .
Note:
If breaker box is not available, refer to 1E-428,
7 On-board check procedure for sensors, DTC: 1
P0192 (Flash code 245) Common rail pressure
sensor fault (low voltage fault, short circuit), List of
Diagnostic Trouble Codes .
Short circuit to common rail pressure sen-
0 200(29008)
sor ground circuit MPa(psi)
Short circuit to ground TSWG0201
2. If the trouble is detected, repair or replace as
Step Item to be Inspection Measuring condition Terminal No. Normal Abnormal
required.
checked method value value
Is the trouble detected? Go to Step 12. Go to Step 9. 6 Open circuit/ Resistance Disconnect the 87 Sens or connector 100Ω or less 10 MΩ or
Replace the common rail (common rail pressure high resistance measurement sensor connector. power supply terminal more
sensor). Key w
s itch OFF
Note:
8 For work procedure, refer to Engine section in the
service manual.
TSWG0198
--- Page 4 ---
4/6HK1 Electronic Control Fuel Injection System (Common Rail Type) 1E-19
About DTC indicated by blinking of diagnosis If the trouble is not detected
lamp In this case, the machine is judged as it operates prop-
While the engine stops, both the current and past DTCs erly. The condition explained by the customer may be
are displayed. the normal condition. Confirm the customer’s complaint
While the engine is operated, the lamp illuminates only comparing with the condition of the machine to that of
if the current DTC occurs. another machine. That condition may mean an intermit-
tent trouble. Confirm the complaint in the situation the
How to read DTC by trouble display monitor customer explains before returning the machine to the
customer.