Isuzu N 2008 Series Workshop Manual page 190

Step
1. Turn OFF the ignition.
2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for a poor
connection at the harness connector of the
10
ECM (pin 19 of J14).
4. Repair the connection(s) as necessary.
Did you find and correct the condition?
Important:
programmed.
Replace the EHCU. Refer to EHCU in Section 4C1
11
ABS/ ASR.
Did you complete the replacement?
Important:
programmed and learned.
12
Replace the ECM. Refer to ECM Replacement.
Did you complete the replacement?
1. Reconnect
harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
13
5. Operate the vehicle within the Conditions for
Running the DTC. You may also operate the
vehicle
observed from the Freeze Frame/ Failure
Records.
Did the DTC fail this ignition?
Observe the DTC Information with a scan tool.
14
Are there any DTCs that you have not diagnosed?
Circuit/ System Testing DTC P0503 (Model without ABS)
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. Disconnect the VSS harness connector.
3
3. Turn ON the ignition, with the engine OFF.
Is DTC P0502 set?
Connect a test lamp between the low reference
circuit (pin 2 of J48) and battery voltage.
4
Does the test lamp illuminate?
Action
Replacement EHCU
Replacement ECM
all previously disconnected
within the conditions
Action
Engine Control System (4JJ1)
Value(s)
—
must be
—
must be
—
—
that you
—
Value(s)
—
—
—
—
Yes
Go to Step 13 Go to Step 12
Go to Step 13
Go to Step 13
Go to Step 3 Go to Step 14
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
Go to Step 7 Go to Step 6
1A-187
No
—
—
System OK
No
Aids