Description of On-Board Diagnostics

DIAGNOSIS SYSTEM DESCRIPTION

The ECU contains a built-in, self-diagnosis system by which troubles with the engine signal network are detected and a "CHECK" engine warning light on the combination meter lights up.

By analyzing various signals, the ECU detects system malfunctions relating to the sensors or actuator.

If a malfunction is detected, the ECU lights up the "CHECK" engine warning light to inform the driver of the occurrence of a malfunction. (For some codes the light does not come on.) The light goes off automatically when the malfunction has been repaired. But the diagnostic code(s) remains stored in the ECU memory (except for code No.51). The ECU stores the code(s) until it is cleared by removing the EFI fuse with the ignition switch off.

The diagnostic code can be read by the number of blinks of the "CHECK" engine warning light when TE1 and E1 terminals on the check connector are connected. When 2 or more codes are indicated, the lowest number (code) will appear first.





"CHECK" ENGINE WARNING LIGHT CHECK

1. The "CHECK" engine warning light will come on when the ignition switch is placed at ON and the engine is not running.

2. When the engine is started, the "CHECK" engine warning light should go off.
If the light remains on, the diagnosis system has detected a malfunction or abnormality in the system.