Function test

The diagnostic is divided into different phases in which the components involved are tested before the actual leak diagnostic begins. The diagnostic is cancelled and a diagnostic trouble code (DTC) is stored if a fault is detected in any of the phases. The diagnostic test works as follows:

• The system must be depressurized. The control module checks that the pump diaphragm is in the resting position. Diagnostic trouble code (DTC) ECM-65, faulty signal, is stored if the control module registers that the position is active
• When the engine is started, a vacuum is generated in the intake manifold. The three-way valve opens a connection to the intake manifold via the non-return valve. The diaphragm is moved to the activated position by the vacuum. Diagnostic trouble code (DTC) ECM-65, high signal, is stored if the control module registers that the diaphragm is still in the resting position
• The three-way valve closes the connection with the intake manifold. The non-return valve closes. A connection to the atmospheric pressure opens. The spring-loaded diaphragm must then return to resting position. Diagnostic trouble code (DTC) ECM 65, low signal, is stored if the diaphragm does not return to the resting position.