DTC 31

CIRCUIT DESCRIPTION
As shown in the illustration above, when a pillar (Vortex generating body) is placed in the path of a uniform flow, vortices called Karman-Vortex are generated downstream of the object. Using this principle, a vortex generator is placed inside the volume air flow meter. By measuring the frequency of the vortices generated, the ECM can determine the volume of air flowing through the volume air flow meter. The vortices are detected by their exerting pressure on thin metal foil (mirror) surfaces and a light emitting element and light receptor (LED and photo transistor) positioned opposite the mirror which senses the vibrations in the mirror optically. The ECM uses these signals mainly for calculation of the basic injection volume and the basic ignition advance angle.





DETECTING CONDITION AND TROUBLE AREA
If the ECM detects diagnostic trouble code "31", it operates the fail safe function, keeping the ignition timing and fuel injection volume constant and making it possible to drive the vehicle.





DIAGNOSTIC CHART





WIRING DIAGRAM














INSPECTION PROCEDURE