Roadmaster V8-350 5.7L (1994)
Evaporative Canister Purge Solenoid Circuit
CIRCUIT DESCRIPTION
EVAP canister purge is controlled by a solenoid valve that allows manifold vacuum to purge the EVAP canister when energized. The PCM
supplies a ground to energize the solenoid valve.
If the "output/field service enable" terminal is grounded with the engine stopped and ignition "ON," or the following conditions are met with the
engine running, the EVAP canister purge solenoid valve will be energized (purge "ON").
^
Engine coolant temperature above 60° C (140° F).
^
Vehicle speed above 2 mph.
^
Throttle off idle, above 1.6%.
CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Checks to see if the solenoid valve is opened or closed. The solenoid valve is normally closed and should open when actuated by Tech 1 or the
"output/field service enable" terminal is grounded.
2. This should energize the solenoid valve and allow the vacuum to drop (purge "ON").
DIAGNOSTIC AIDS
Normal operation of the EVAP canister purge solenoid valve is described as follows:
With the ignition "ON," engine "OFF," "output/field service enable" terminal grounded, the EVAP canister purge solenoid valve should be
energized.