Diagnostic System Check - Engine Controls - Isuzu N 2008 Series Workshop Manual

1A-32 Engine Control System (4JJ1)
Diagnostic System
Controls
Description
The Diagnostic System Check - Engine Controls is an
organized approach to identifying a condition that is
created by a malfunction in the electronic engine
control system. The Diagnostic System Check must be
the starting point for any driveability concern. The
Diagnostic System Check directs the service technician
to the next logical step in order to diagnose the
concern. Understanding and correctly using the
diagnostic table reduces diagnostic time, and prevents
the replacement of good parts.
Test Description
The numbers below refer to the step numbers on the
diagnostic table.
2. Lack of communication may be because of a partial
or a total malfunction of the serial data circuit.
7. The presence of DTCs which begin with U, indicate
that some other module is not communicating.
10. If there are other modules with DTCs set, refer to
the DTC list. The DTC list directs you to the appropriate
diagnostic procedure. If the control module stores
multiple DTCs, diagnose the DTCs in the following
order:
• Component level DTCs, such as sensor DTCs,
solenoid DTCs, actuator DTCs, and relay DTCs.
Diagnose the multiple DTCs within this category in
numerical order. Begin with the lowest numbered
DTC, unless the diagnostic table directs you
otherwise.
Diagnostic System Check - Engine Controls (Euro 4 Specification)
Step
Install a scan tool.
1
Does the scan tool turn ON?
1. Turn ON the ignition, with the engine OFF.
2. Attempt to establish communication with the
2
ECM.
Does the scan tool communicate with the ECM?
Notice: If an immobilizer system is active the ECM
will disable the fuel injection causing the engine to
stall immediately after starting and energize the
3
starter cut relay to disable cranking. Attempt to
crank the engine.
Does the engine crank?
Check - Engine
Action
Diagnostic System Check Engine Controls
Important:
• DO NOT perform this diagnostic if there is not a
driveability concern, unless another procedure
directs you to this diagnostic.
• Before you proceed with diagnosis, search for
applicable service bulletins.
• Unless a diagnostic procedure instructs you, DO
NOT clear the DTCs.
• If there is a condition with the starting system, refer
to the Starting System in Section 1E Engine
Electrical.
• Ensure the battery has a full charge.
• Ensure the battery cables (+) (-) are clean and
tight.
• Ensure the ECM grounds are clean, tight, and in
the correct location.
• Ensure the ECM harness connectors are clean
and correctly connected. DO NOT attempt to crank
the engine with
disconnect.
• Ensure the ECM terminals are clean and correctly
mating.
• Ensure the fuel injector ID code data is correctly
programmed in to the ECM.
• Ensure the immobilizer security information is
correctly programmed
immobilizer control unit (ICU).
• If there are fuel system DTC's (P0087, P0088,
P0089, P0093 or P1093), diagnose sensor DTCs,
solenoid DTCs, actuator DTCs and relay DTCs
first.
• If there are DPD system DTC's (P1455, P1471,
P242F, P2452, P2453 or P2458), diagnose sensor
DTCs, solenoid DTCs, actuator DTCs and relay
DTCs first.
Value(s) Yes
—
Go to Step 2
—
Go to Step 3
—
Go to Step 4
ECM harness connectors
into the ECM
No
Go to Scan Tool
Does Not Power Up
Go to Scan Tool
Does Not
Communicate with
CAN Device
Go to Step 5
and