Description
DATA TROUBLE CODE: 31SYSTEM: Manifold Absolute Pressure Sensor
WIRING DIAGRAM
CIRCUIT DESCRIPTION
By a built-in sensor unit, the manifold absolute pressure sensor detects the intake manifold pressure as a voltage. The engine control module (ECM) then determines the basic injection duration and basic ignition advance angle based on this voltage.
Since the manifold absolute pressure sensor does not use the atmospheric pressure as a criterion, but senses the absolute pressure inside the intake manifold (the pressure in proportion to the preset absolute vacuum 0), it is not influenced by fluctuations in the atmospheric pressure due to high altitude and other factors. This permits it to control the air-fuel ratio at the proper level under all conditions.
DIAGNOSTIC TROUBLE CODE DETECTING CONDITION
- Open or short in manifold absolute pressure sensor circuit for 0.5 seconds or more.
TROUBLE AREA
- Open or short in manifold absolute pressure sensor circuit.
- Manifold absolute pressure sensor.
- ECM
NOTE: 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.