Roadmaster Estate Wagon V8-350 5.7L VIN P SFI (1996)
EVAP Vacuum Switch: Description and Operation
EVAP Vacuum Switch
DESCRIPTION
The EVAP Purge Vacuum Switch is used by the PCM to monitor EVAP canister purge solenoid operation and purge system integrity. The EVAP
Purge Vacuum Switch should be closed to ground with no vacuum present (0% EVAP Purge PWM). With EVAP Purge PWM at 25% or greater,
the EVAP Purge Vacuum Switch should open.
An incorrect EVAP Purge system flow should set a DTC P0441. A continuous purge condition with no purge commanded by the PCM should set
a DTC P1441. Refer to Evaporative Emission (EVAP) Control System for a complete description of the EVAP system.
The Evaporative Emission (EVAP) canister purge solenoid valve and the EVAP Vacuum switch diagnosis is covered in the following DTCs:
^
P0441
^
P0443
^
P1441
