Scan Tool Does Not Communicate With Can Device (Euro 4 Specification); Scan Tool Does Not Communicate With - Isuzu N 2008 Series Workshop Manual

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 and the
immobilizer control unit (ICU) communicate with each
other over the same CAN link. The ECM, the electric
hydraulic control unit (EHCU), the transmission control
module (TCM), the data recording module (DRM) and
the instrument panel (IP) cluster communicate with
each other over the separated CAN link that does not
affect to the scan tool communication.
Circuit/ System Testing Scan Tool Does Not Communicate with CAN Device (Euro 4 Specification)
Step
Did you perform the Diagnostic System Check -
1 Engine Controls?
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.
2 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?
1. Inspect
connections and for corrosion at the data link
connector (DLC) (pins 6 and 14 of B31).
3
2. Repair the connection(s) as necessary.
Did you find and correct the condition?
1. Inspect
connections and for corrosion at the ECM E12
and J14 connectors.
4
2. Repair the connection(s) as necessary.
Did you find and correct the condition?
1. Check the ECM (30A) slow blow fuse and
ECM Main (10A) fuse in the chassis fuse
block, ECM (10A) fuse in the cabin fuse block.
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.
5
3. Disconnect the ECM J14 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 J14).
Does the test lamp illuminate?
Action
for an intermittent,
for an intermittent,
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
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Value(s)
—
—
for poor
—
for poor
—
—
Engine Control System (4JJ1)
Yes
Go to Step 2
Go to Intermittent
Conditions
Go to Step 18
Go to Step 18
Go to Step 7
1A-47
No
Go to Diagnostic
System Check -
Engine Controls
Go to Step 3
Go to Step 4
Go to Step 5
Go to Step 6