Diagnostic Trouble Code (Dtc) P1441 Evap System Flow During Non-Purge - Isuzu Trooper 1999 Workshop Manual

6E–416
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P1441 EVAP System Flow During Non-Purge

Circuit Description
Canister purge is controlled by a solenoid valve that
allows manifold vacuum to purge the canister.
powertrain control module (PCM) supplies a ground to
energize the solenoid valve (purge "ON"). The EVAP
purge solenoid control is pulse-width modulated (PWM)
or turned "ON" and "OFF" several times a second. The
duty cycle (pulse width) is determined by engine
operating conditions including load, throttle position,
coolant temperature and ambient temperature. The duty
cycle is calculated by the PCM and the output is
commanded when the appropriate conditions have been
met.
The EVAP purge vacuum switch is a normally closed
switch positioned in the purge line between the canister
and to EVAP purge solenoid. The EVAP purge vacuum
switch will open when vacuum increases to greater than 5
inches of water in the purge line. The PCM monitors the
EVAP purge vacuum switch signal to determine if the
evaporative emission control system is working properly.
If the switch is open (purge flow detected) when the PCM
is not commanding the EVAP purge solenoid "ON," DTC
P1441 will be set.
Conditions for Setting the DTC
f No active ECT sensor, IAT sensor, MAP sensor,
vacuum switch, or TP sensor DTCs set.
f BARO reading is above 85 kPa.
f Engine coolant temperature is below 70°C (158°F).
f Start-up intake air temperature (IAT) and start-up
engine coolant temperature (ECT) are both above 5°C
(41°F).
The
f The difference between start-up ECT and start-up IAT
is less than 25°C (45°F).
f TP sensor indicates a throttle position above 12%.
f Battery voltage is between 11.5 volts and 16 volts.
f Engine speed is between 800 and 6,000 RPM.
f Canister purge duty cycle is below 3%.
f Canister purge vacuum switch is open, which results
in the PCM signal voltage (from the vacuum switch
input) being approximately 12 volts.
f All conditions are present for at least 3 seconds.
Action Taken When the DTC Sets
f The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.
f The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
f The PCM will turn the MIL "OFF" on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.
f A history DTC P1441 will clear after 40 consecutive
warm–up cycles have occurred without a fault.
D06RW018