Isuzu 2008MY N Series Workshop Manual page 236

Step
1. Leave the DMM connected to the boost
pressure sensor harness connector.
2. Turn OFF the ignition.
3. Disconnect the intake throttle valve harness
5
connector.
4. Turn ON the ignition, with the engine OFF.
Does the DMM voltage change to more than
the specified value?
1. Leave the DMM connected to the boost
pressure sensor harness connector.
2. Turn OFF the ignition.
3. Disconnect the crankshaft position (CKP)
6
sensor harness connector.
4. Turn ON the ignition, with the engine OFF.
Does the DMM voltage change to more than
the specified value?
1. Leave the DMM connected to the boost
pressure sensor harness connector.
2. Turn OFF the ignition.
3. Disconnect the exhaust differential pressure
7
sensor harness connector.
4. Turn ON the ignition, with the engine OFF.
Does the DMM voltage change to more than
the specified value?
1. Test the 5 volts reference circuit 3 between the
ECM (pin 80 of J-14) and the exhaust
differential pressure sensor (pin 3 of J-33) for
a short to ground or short to the low reference
circuit.
2. Test the 5 volts reference circuit 4 between the
ECM (pin 95 of E-12) and the following
components for a short to ground or short to
8
the low reference circuit:
• CKP sensor (pin 3 of E-20)
• Boost pressure sensor (pin 3 of E-24)
• Intake throttle position sensor (pin 5 of E-
16)
3. Repair the circuit(s) as necessary.
Did you find and correct the condition?
1. Test the 5 volts reference circuit 3 between the
ECM (pin 80 of J-14) and the exhaust
differential pressure sensor (pin 3 of J-33) for
a short to battery or ignition voltage.
2. Test the 5 volts reference circuit 4 between the
ECM (pin 95 of E-12) and the following
components for a short to battery or ignition
voltage.
9
• CKP sensor (pin 3 of E-20)
• Boost pressure sensor (pin 3 of E-24)
• Intake throttle position sensor (pin 5 of E-
16)
3. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Action
Engine Control System (4HK1)
Value(s) Yes
4.5 volts
Go to Step 11
4.5volts
Go to Step 12
4.5volts
Go to Step 13
—
Go to Step 15
—
Go to Step 15
1A-233
No
Go to Step 6
Go to Step 7
Go to Step 8
Go to Step 14
Go to Step 14