Description
DATA TROUBLE CODE: 31SYSTEM: Volume Air Flow Meter Circuit
CIRCUIT DESCRIPTION
As shown in the figures, 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 Engine Control Module 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 optically senses the vibrations in the mirror. The Engine Control Module uses these signals mainly for calculation of the basic injection volume and the basic ignition advance angle.
DIAGNOSTIC TROUBLE CODE DETECTING CONDITION
- All conditions below are detected.
- No Volume Air Flow Meter signal to Engine Control Module for 2 seconds when engine speed is above 300 rpm.
- Engine stall.
TROUBLE AREA
- Open or short in Volume Air Flow Meter circuit.
- Volume Air Flow Meter.
- Engine Control Module.
NOTE: If the Engine Control Module records 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.
Malfunction Indicator Lamp
Normal Mode On
Test Mode Na