Isuzu 2008MY N Series, Руководство по ремонту

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Engine Control System (4HK1) 1A-51
Scan Tool Does Not Communicate with
CAN Device (Euro 4 Specification)
Circuit Description
The ECM communicates with the scan tool over the
controller area network (CAN) link. The ECM,
transmission control module (TCM), electric hydraulic
control unit (EHCU) and the data recording module
(DRM) communicate with each other over the
separated CAN link that does not affect to the scan tool
communication.
Diagnostic Aids
The following conditions will cause a loss of CAN serial
data communication between the scan tool and the
ECM.
• A CAN serial data circuit open
• A CAN serial data circuit shorted to ground
• A CAN serial data circuit shorted to voltage
• An internal condition within a module or connector
on the CAN serial data circuit, that causes a short
to voltage or ground to the CAN serial data circuit
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Circuit/ System Testing Scan Tool Does Not Communicate with CAN Device (Euro 4 Specification)
Step Action Value(s) Yes No
1
Did you perform the Diagnostic System Check
- Engine Controls?
—
Go to Step 2
Go to Diagnostic
System Check -
Engine Controls
2
Important: Make sure the CANdi module is not
malfunctioning. When functioning properly, the
CANdi module LED will be flashing. In the event of
a problem, the LED will be continually illuminated
or not illuminated.
1.
Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. Attempt to establish communication with the
ECM.
Does the scan tool communicate with the
ECM?
—
Go to Intermittent
Conditions Go to Step 3
3
1. Inspect for an intermittent, for poor
connections and for corrosion at the data link
connector (DLC) (pins 6 and 14 of B-31).
2. Repair the connection(s) as necessary.
Did you find and correct the condition?
—
Go to Step 18 Go to Step 4
4
1. Inspect for an intermittent, for poor
connections and for corrosion at the ECM E-
12 and J-14 connectors.
2. Repair the connection(s) as necessary.
Did you find and correct the condition?
—
Go to Step 18 Go to Step 5
5
1. Check the ECM (30A) slow blow fuse, ECM
MAIN (15A) fuse and ECM (10A) fuse.
Replace and retest if open. If any fuse
continues to open, repair the short to ground
on each circuit fed by that fuse.
2. Turn OFF the ignition.
3. Disconnect the ECM J-14 harness connector.
4. Turn ON the ignition, with the engine OFF.
5. Connect a test lamp to ground and check for
voltage at ignition voltage supply circuit at the
ECM (pin 24 of J-14).
Does the test lamp illuminate?
—
Go to Step 7 Go to Step 6
LG4HKED-WE-0871.book 51 ページ ２００７年１１月２９日 木曜日 午後６時２９分