Isuzu 4JA1 Workshop Manual page 356

6E-102 Engine Control System (4JH1)
Step
3 1. Turn OFF the ignition.
2. Inspect for the following conditions:
•
Vacuum hoses are damaged or kinked
•
Misrouted vacuum hoses
•
A turbocharger solenoid valve is damaged
•
A vacuum pump is damaged
•
A vacuum regulating valve is damaged
•
A turbocharger
damaged
•
Contaminated, skewed or slow vacuum
pressure sensor
3. Repair or replace as necessary.
Did you find and correct the condition?
4 1. Turn ON the ignition, with the engine OFF.
2. Observe the Vacuum Pressure Sensor and
Barometric Pressure (BARO) with the scan tool.
Does the scan tool indicate that the difference
between the Vacuum Pressure Sensor and doubled
BARO is less than the specified value?
5 1. Observe the BARO parameter with the scan tool.
2. Compare the BARO value to the range specified
in the altitude vs. barometric pressure table.
Refer to Altitude vs. Barometric Pressure.
Is the BARO parameter within the range specified?
6 1. Turn OFF the ignition.
2. Disconnect the vacuum pressure sensor harness
connector.
3. Inspect for an intermittent and for a poor
connection at the vacuum pressure sensor
harness connector (pin 2 of C-124 connector).
4. Disconnect the engine control module (ECM)
harness connector.
5. Inspect for an intermittent, for a poor connection
and corrosion on vacuum pressure sensor circuit
at the harness connector of the ECM (pin 15 of
C-57 connector).
6. Test for high resistance on vacuum pressure
sensor low reference circuit.
7. Repair the
necessary.
Did you find and correct the condition?
7 1. Turn OFF the ignition.
2. Disconnect
turbocharger wastegate valve that is connected
to the vacuum pressure sensor and the
turbocharger solenoid valve.
3. Start the engine and accelerate the engine as
necessary.
Is there boost pressure leak from the turbocharger
wastegate valve port?
Action
wastegate valve
connection(s) or circuit(s)
the vacuum hose from
Value(s)

is
10 hPa


as
the

Yes
Go to Step 15 Go to Step 4
Go to Step 7 Go to Step 5
Go to Step 6 Go to Step 14
Go to Step 15 Go to Step 10
Go to Step 13 Go to Step 8
No