California System Description

EFI System (California) (1 of 2):

EFI System (California) (2 of 2):

When any troubles, as listed below, occurs in EFI system, the ECM activates the "CHECK ENGINE" light while engine is running. This warns the driver of an occurrence of such trouble, and stores the data (where the trouble occurred) in its back-up memory. The memory is kept even if the trouble was only temporary and disappeared immediately. It is not erased unless either the engine is started and stopped 50 times or more with the EFI system in good condition, or the power to the ECM is shut "OFF" for 20 seconds or longer. The ECM also indicates defective area in memory by means of flashing the "CHECK ENGINE" light at the time of inspection (i.e. when the diagnosis terminal is grounded, and ignition switch is turned "ON").

A. When the ECM receives a defect informing signal from any one of following sensors and circuits, or no signal at all.

- Oxygen sensor
- Manifold Air Temperature (MAT) sensor
- Manifold Absolute Pressure (MAP) sensor
- Coolant Temperature Sensor (CTS)
- Throttle Position Sensor (TPS)
- Idle switch circuit
- Lock-up circuit (For A/T vehicle)
- 5th switch circuit (For M/T vehicle)
- Ignition circuit

B. When problems exists in the EGR system, or re-circulated exhaust gas temperature sensor is defective.

C. When the Central Processor Unit (CPU) of the ECM fails to operate.

NOTE: Even when a trouble occurs in lock-up signal, 5th switch signal circuit, or when the idle switch circuit becomes open, the ECM does not indicate it (or activate "CHECK ENGINE" light) while engine is running. When that troubled circuit regains good condition, the memory of defective area will be erased automatically even if the power circuit to ECM is not opened.

"CHECK ENGINE" light:

The "CHECK ENGINE" light is located at the top of the instrument cluster. It indicates defective area identified by the self-diagnosis function of the ECM. It also lights when the following condition applies:

A. When the ignition switch is "ON" and engine is not running. When engine speed is lower than 500 rpm, the "CHECK ENGINE" light turns "ON" for the purpose of its circuit check, but turns "OFF" once the engine is started, (when engine speed is higher than 500 rpm) regardless of EFI system condition.

FAIL-SAFE FUNCTION:

When a failure occurs, a signal indicating such failure is sent to the ECM, which judges that signal as such. However, control over the injector, ISC solenoid valve, and other components are maintained on the basis of the standard signals stored in the memory of the ECM, while ignoring that failure signal. This function is called "fail-safe function." Thus, with this function, a certain level of engine performance is available even when some failures occur in these sensors or their circuits. This allows the vehicle to run even if a failure exist.

- Coolant Temperature Sensor (CTS)
- Throttle Position Sensor (TPS)
- Manifold Air Temperature (MAT) sensor
- Manifold Absolute Pressure (MAP) sensor

BACK-UP FUNCTION:

Even when the microcomputer in the ECM fails to operate properly, the back-up circuit in the ECM controls operation of the injector on the basis of the signals from the pressure sensor, so as to least impair driving performance.