Chart 7

Diagnostic Chart:

Schematic:

The PCM contains an Output Driver Module (ODM) which controls the EVAP vent solenoid circuit ground. The ODM monitors the feedback voltage level on circuit 1310 at the PCM when the device is being commanded On or Off. When the device is commanded Off (circuit not grounded), the voltage level at the PCM should be high (ignition voltage). When the device is commanded On (circuit grounded), the voltage level at the PCM should be low. Chart 5 diagnoses a low circuit voltage fault in which the PCM detected lower than normal feedback voltage when the EVAP vent solenoid was commanded Off.

DTC PARAMETERS
DTC P1640 will set if EVAP vent solenoid feedback voltage is less than 4.0 volts when EVAP vent solenoid is commanded Off when:
^ Condition exists for longer than 6 seconds
^ Engine is running

DTC P1640 diagnostic runs continuously with engine running.

P1640 is a (type C) DTC

DIAGNOSTIC AIDS
To locate an intermittent problem, use Scan to monitor EVAP VENT CKT OPEN SHORT TO GND with ignition On, engine Off. When a fault (open or short to ground) exists, the Scan tool will display YES.

EVAP vent solenoid resistance: 18-27 ohms