Isuzu N 2008 Series Workshop Manual page 183

1A-180 Engine Control System (4JJ1)
Circuit/ System Testing DTC P0478
Step
Did you perform the Diagnostic System Check -
1 Engine Controls?
1. Install a scan tool.
2. Perform the Exhaust Brake Control with a
scan tool.
2
3. Command the solenoid valve ON and OFF.
Does the solenoid valve click with each command?
1. Turn OFF the ignition.
2. Disconnect the exhaust brake solenoid valve
harness connector.
3
3. Turn ON the ignition, with the engine OFF.
4. Monitor the DTC Information with a scan tool.
Is DTC P0477 set, but not P0478?
1. Test the control circuit between the ECM (pin
15 of J14) and the solenoid valve (pin 2 of
J26) for a short to battery or ignition voltage.
4
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Replace the exhaust brake solenoid valve.
5
Did you complete the replacement?
Important:
programmed and learned.
6
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. Perform the Exhaust Brake Control with a
7
scan tool.
4. Command the solenoid valve ON and OFF.
Does the solenoid valve click with each command?
Observe the DTC Information with a scan tool.
8
Are there any DTCs that you have not diagnosed?
Action
Replacement ECM
all previously disconnected
Value(s)
—
—
—
—
—
must be
—
—
—
Yes
Go to Diagnostic
System Check -
Go to Step 2 Engine Controls
Go to Diagnostic
Aids
Go to Step 5
Go to Step 7
Go to Step 7
Go to Step 7
Go to Step 8
Go to DTC List
No
Go to Step 3
Go to Step 4
Go to Step 6
—
—
Go to Step 3
System OK