Isuzu 2008MY N Series Workshop Manual page 150

Step
1. Inspect the following for possible causes of
high boost pressure.
• Turbocharger nozzle control solenoid
valve for a stuck condition. Perform the
Turbocharger Control with a scan tool.
• Intake throttle valve sticking. Perform the
Intake Throttle Solenoid Control with a
scan tool.
5
• Oil in the air induction tubing causing an
incorrect boost pressure sensor signal.
When there is adhesion of oil inside of
the tubing, intercooler or turbocharger it
needs to be wiped off.
2. Repair or replace as necessary.
Did you find and correction the condition?
1. Turn OFF the ignition.
2. Disconnect
harness connector.
3. Inspect for an intermittent and for a poor
connection at the harness connector of the
boost pressure sensor (pin 2 of E-24).
4. Disconnect the ECM harness connector.
5. Inspect for an intermittent, for a poor
6
connection and corrosion at the harness
connector of the ECM (pin 109 of E-12).
6. Test for high resistance of the low reference
circuit.
7. Repair the connection(s) or circuit(s) as
necessary.
Did you find and correct the condition?
1. Turn OFF the ignition.
2. Disconnect
connector.
3. Inspect for an intermittent and for poor
connections at the harness connector of the
BARO sensor (pins 2 and 3 of B-121).
4. Disconnect the ECM harness connector.
5. Inspect for
7
connections and corrosion at the harness
connector of the ECM (pins 61 and 71 of E-
12).
6. Test for high resistance on each circuit.
7. Repair the connection(s) or circuit(s) as
necessary.
Did you find and correct the condition?
Replace the boost pressure sensor. Refer to Boost
Pressure Sensor in Section 1J Induction.
8
Did you complete the replacement?
Replace the BARO sensor. Refer to BARO Sensor
Replacement.
9
Did you complete the replacement?
Action
the boost pressure
the BARO sensor harness
an intermittent, for
Engine Control System (4HK1)
Value(s)
—
sensor
—
poor
—
—
—
Yes
Go to Diagnostic
Go to Step 10
Go to Step 10 Go to Step 8
Go to Step 10 Go to Step 9
Go to Step 10
Go to Step 10
1A-147
No
Aids
—
—