Chart 3

Diagnostic Chart:

Schematic:

The EVAP purge solenoid is feed ignition voltage on the high side and controlled by an Output Driver Module (ODM) in the PCM on the low side. When PCM is not commanding the EVAP purge solenoid On, it expects to see ignition voltage at the feedback. When the solenoid is commanded On, it expects to see zero volts at the feedback.

DTC PARAMETERS
DTC P1640 will set if feedback voltage does not agree with expected voltage (based on commanded state of output).

DIAGNOSTIC AIDS
Use Scan tool to command EVAP purge solenoid On or Off and monitor EVAP vent CKT feedbacks while manipulating harness to find intermittents.