Circuit Description

EVAP vent valve is supplied power via main relay (switched battery feed circuit). ECM controls valve by grounding control circuit via an internal driver. Primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by ECM. When ECM is commanding a component on, voltage of control circuit should be low (near zero volt). When ECM is commanding control circuit to component off, voltage should be high (near battery voltage). If fault detection circuit senses a voltage other than what is expected, this DTC will set.

ECM will monitor EVAP vent valve circuit for short to ground, short to voltage, open circuit, open component or an internally shorted or excessively low resistance on EVAP valve circuit. When ECM detects any of these malfunctions, this DTC will set and affected driver will be disabled. ECM will continue to test circuit and if fault disappears, driver will be reactivated.

Conditions required to set DTC are:

• A short to ground, open, or short to battery voltage detected on control circuit.