Isuzu 2008MY N Series Workshop Manual page 207

1A-204 Engine Control System (4HK1)
Step
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?
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 also set?
Connect a test lamp between the low reference
circuit (pin 2 of J-48) and battery voltage.
4
Does the test lamp illuminate?
1. Test the signal circuit between the ECM (pin
19 of J-14) and the VSS (pin 3 of J-48) for a
short to battery or ignition voltage.
5
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Repair the open circuit or high resistance on the
low reference circuit between the VSS (pin 2 of J-
48) and ground terminal. Clean or tighten ground
6
as necessary.
Did you complete the repair?
1. Inspect for an intermittent and for a poor
connection at the harness connector of the
VSS (pin 2 of J-48).
7
2. Repair the connection(s) as necessary.
Did you find and correct the condition?
Replace the VSS. Refer to Vehicle Speed Sensor in
Section 9E Instrumentation/Driver Info.
8
Did you complete the replacement?
Important:
programmed and learned.
9
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.
10
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.
11
Are there any DTCs that you have not
diagnosed?
Action
Replacement ECM
all previously disconnected
within the conditions
Value(s)
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must be
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that you
—
Yes
Go to Diagnostic
Go to Step 3
Go to Step 4 Go to Step 5
Go to Step 7 Go to Step 6
Go to Step 10 Go to Step 9
Go to Step 10
Go to Step 10 Go to Step 8
Go to Step 10
Go to Step 10
Go to Step 3 Go to Step 11
Go to DTC List
No
Aids
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—
—
System OK