Ecm Voltage And Continuity Test/Measurement; Functional Check List; Hearing Diagnostic; Key Points On Hearing - Isuzu 4HL1 Workshop Manual

1A-44 Engine Control System

ECM Voltage and Continuity Test/Measurement

To test and measure the ECM for voltage and
continuity, use a circuit breaker box and 4HL1 adapter
harness.
1
18
35
52
69
86
103
120

Functional Check List

Hearing
On-Board Diagnostic System
Check
Inactive CHECK ENGINE Lamp
(MIL) Check
Active CHECK ENGINE Lamp
(MIL) Check
ECM Power Supply and
Grounding System Circuit Check

Hearing Diagnostic

1. Using the Engine Control System Diagnostic
Chart, completely hear and comprehend the
customer complaint.
Reference:
Proceed the process by focusing on the possible
faulty system estimated from the fault (fact)
instead of random hearing.
2. Judge the failure information accurately.
Comprehend the situation concretely based on
5W1H principle.
Example: Low
permanent generation, vicinity of engine, metallic
sound, etc.
V
17
A
34
51
68
B
85
102
C
119
130
LNW21ASH010501
The objective is to comprehend the symptom completely based on the
customer complaint and provide accurate diagnostic.
The objective is to identify the faulty portion on the electronic engine control
system. (Checking procedure)
The objective is to check the CHECK ENGINE lamp (MIL) when it is not
turned on even after starter switch turn-on.
The objective is to check the CHECK ENGINE lamp (MIL) when it does not
blink (i.e., it keeps continuous lighting) even after diagnostic switch turn-on.
The objective is to check ECM power supply and grounding system circuits
when they seem to be faulty.
temperature, startup

Key points on hearing

• What
• When
• Where
• State
• Result
stage,
• Faulty event
• Date and time, generation
frequency
• Situation of road
• Running condition, driving
condition, weather conditions
• Feeling of fault