Isuzu N 2008 Series Workshop Manual page 215

1A-212 Engine Control System (4JJ1)
Step
1. Turn OFF the ignition.
2. Disconnect the ECM harness connector.
3. Inspect
connections and corrosion at the harness
connector of the ECM (pin 2, 5, 21 and 40 of
J14).
4. Test for an open circuit or high resistance on
each relay circuit.
• Between pins 2 and 5 of J14 and pin 2 of
X18
5
• Between pins 21 and 40 of J14 and pin 3
of X18
• Between ECM (30A) slow blow fuse and
pin 1 of X18
• Between pin 5 of X18 and chassis
ground (J13)
5. Repair the connection(s) or circuit(s) as
necessary.
Did you find and correct the condition?
Replace the ECM main relay.
6
Did you complete the replacement?
Important:
programmed and learned.
7
Replace the ECM. Refer to ECM Replacement.
Did you complete the replacement?
1. Reconnect all previously disconnected relay
or harness connector(s).
2. Clear the DTCs with a scan tool.
8
3. Turn OFF the ignition for 30 seconds.
4. Turn ON the ignition, with the engine OFF.
Did the DTC fail this ignition?
Observe the DTC Information with a scan tool.
9
Are there any DTCs that you have not diagnosed?
Circuit/ System Testing DTC P0687
Step
Did you perform the Diagnostic System Check -
1 Engine Controls?
1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
2
4. Monitor the DTC Information with a scan tool.
Does the DTC fail this ignition?
1. Turn OFF the ignition for 30 seconds.
2. Remove the ECM main relay.
3
3. Turn ON the ignition, with the engine OFF.
Is DTC P0685 set?
Action
for an intermittent,
Replacement ECM
Action
Value(s)
for poor
—
—
must be
—
—
—
Value(s)
—
—
—
Yes
Go to Step 8 Go to Step 7
Go to Step 8
Go to Step 8
Go to Step 3 Go to Step 9
Go to DTC List
Yes
Go to Diagnostic
System Check -
Go to Step 2 Engine Controls
Go to Diagnostic
Go to Step 3
Go to Step 4 Go to Step 5
No
—
—
System OK
No
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