Isuzu 2000 Trooper Workshop Manual page 1199

6E–330
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
D The EVAP system is unable to achieve or maintain
vacuum during the diagnostic test.
D Above conditions are present for 60 to 180 seconds.
Action Taken When the DTC Sets
D The PCM will illuminate the MIL during the second key
cycle in which the DTC sets.
D The PCM will store conditions which were present
when the DTC set as Freeze Frame and in the Failure
Records data.
Conditions for Clearing the MIL/DTC
D The PCM will turn the MIL "OFF" when the diagnostic
has been run and the fault condition is no longer
present.
D A history DTC P0440 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
D DTC P0440 can be cleared by using the Tech 2 "Clear
Info" function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
D Cracked or punctured EVAP canister.
D Damaged or disconnected source vacuum line, EVAP
purge line, vent hose or fuel tank vapor line.
D Poor connection at PCM – Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal to wire connection.
D Damaged harness–Inspect the wiring harness to the
EVAP canister vent solenoid, EVAP canister purge
solenoid and the fuel tank pressure sensor for an
intermittent open or short circuit.
Step
1 Was the "On-Board Diagnostic (OBD) System Check"
performed?
2 Is DTC P0452 or P0453 also set?
3 1. Ignition "OFF."
2. Remove the fuel cap.
3. Ignition "ON."
4. Observe "Fuel Tank Pressure" on the Tech 2.
Does the Tech 2 indicate "Fuel Tank Pressure" at the
specified value?
4 1. Replace the fuel cap.
2. Engine is running.
3. Observe "Fuel Tank Vacuum" on the Tech 2.
Does Tech 2 indicate "Fuel Tank Vacuum" at the
specified value?
DTC P0440 – EVAP System
Action
D Kinked, pinched, or plugged vacuum source, EVAP
purge, or fuel tank vapor line–Verify that the lines are
not restricted.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. If an EVAP canister vent solenoid or an EVAP
canister purge solenoid electrical fault is present,
the purge system will not operate correctly.
Repairing the electrical fault will very likely correct
the condition that set DTC P0440.
3. Checks the fuel tank pressure sensor at ambient
pressure.
4. Determines whether or not the EVAP system can be
sealed sufficiently to be pressurized. If not, the
large leak must be located and corrected before
continuing with diagnosis.
5. Verifies that the fuel tank pressure sensor accurately
reacts to EVAP system pressure changes.
8. Checks for a blocked EVAP canister purge solenoid.
The PCM commands the EVAP canister purge
solenoid "OFF" (open) and the vent solenoid "ON"
(closed) with the Tech 2 "System Perf." EVAP
output control function activated. Any pressure in
the system should be released through the EVAP
canister purge solenoid within a few seconds when
"System Perf." is activated.
9. Ensures that sufficient source vacuum is present at
the EVAP canister purge solenoid.
Value(s)
— Go to Step 2
Go to other
—
DTC first
Go to Step 4
1.51 V
Go to Step 7
1.47–1.51 V
Yes No
Go to OBD
System
Check
Go to Step 3
Go to DTC
P0452 or
DTC P0453
Go to Step 6