Isuzu 2008MY N Series Workshop Manual page 208

Circuit/ System Testing DTC P0503 (Model with 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. Start the engine.
2
4. Monitor the DTC Information with a scan tool.
Does the DTC fail this ignition?
Observe the ABS DTCs information with a scan
tool.
3
Is DTC C0251, C0252, C0253, C0254,
C0261, C0262, C0263 or C0264 set?
1. Turn OFF the ignition for 30 seconds.
2. Disconnect the EHCU harness connector.
4
3. Turn ON the ignition, with the engine OFF.
Is DTC P0502 also set?
1. Test the signal circuit between the ECM (pin
19 of J-14) and the EHCU (pin 14 of J-22) for
a short to battery or ignition voltage.
5
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
1. Inspect for an intermittent and for a poor
connection at the harness connector of the
EHCU (pin 14 of J-22).
6
2. Repair the connection(s) as necessary.
Did you find and correct the condition?
Important:
programmed.
Replace the EHCU. Refer to EHCU in Section 4C1
7
ABS/ASR.
Did you complete the replacement?
Important:
programmed and learned.
8
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.
9
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?
Action
Replacement EHCU
Replacement ECM
all previously disconnected
within the conditions
Engine Control System (4HK1)
Value(s)
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must be
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must be
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that you
Yes
Go to Diagnostic
System Check -
Go to Step 2 Engine Controls
Go to Diagnostic
Go to Step 3
Go to Applicable
DTC
Go to Step 6
Go to Step 9
Go to Step 9
Go to Step 9
Go to Step 9
Go to Step 3
1A-205
No
Aids
Go to Step 4
Go to Step 5
Go to Step 8
Go to Step 7
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Go to Step 10