Isuzu C22NE Workshop Manual page 295

CANISTER PURGE CONTROL SOLENOID VALVE CHECK (IF APPLICABLE)
Circuit Description
Canister purge is controlled by a solenoid valve that
allows manifold vacuum to purge the canister. The
engine control module (ECM) supplies a ground to
energize the solenoid valve (purge ON). The EVAP
(purge solenoid control is turned ON time) is
determined by engine operating conditions including
load, throttle position, coolant temperature and
ambient temperature. The duty cycle is calculated by
the ECM and the purge solenoid is enabled when the
appropriate conditions have been met:
• The engine run time after start is more than 60
seconds.
• The engine coolant temperature is above 30°C
(86°F).
• The fuel control system is operating in the "Closed-
Loop" mode (If applicable).
EVAPORATIVE EMISSIONS (EVAP)
DRIVEABILITY AND EMISSIONS 6E1-125
Diagnostic Aids
• Make a visual check of vacuum hoses.
• Check the throttle body for possible cracked or
plugged vacuum block.
• Check the malfunction indicator lamp for a possible
mechanical problem.
Test Description
The number(s) below refer to the step number(s) on
the Diagnostic Chart.
1. Check to see if the solenoid is open or closed. The
solenoid is normally de-energized in this step, so it
should be closed.
2. This step checks to determine if the solenoid was
open due to an electrical circuit problem or a
defective solenoid.
3. This should normally energize the solenoid,
opening the valve and allowing the vacuum to drop
(Purge ON).