Description of On-Board Diagnostics

CHECK ENGINE MALFUNCTION INDICATOR LAMP

INSPECTION
1. Check that when the ignition switch is turned on. the light illuminates for about 5 seconds and then goes out.
2. If the light does not illuminate, check for open circuit in harness, blown fuse and blown bulb.

DIAGNOSTIC TEST MODE
The engine control module monitors the input/output signals (some signals at all times and the others under specified conditions) of the engine control module.

When it is noticed that an irregularity has continued for a specified time, the engine control module will set the diagnostic trouble code, and output it to the diagnostic output terminal.

There are 17 diagnostic items, including the normal state, and the diagnostic results can be read out with a scan tool. Moreover, since memorization of-the diagnostic trouble codes is backed up directly by the battery, the diagnostic results are memorized even if the ignition key is turned off. The diagnostic trouble codes will, however, be erased when the battery terminal or the engine control module connector is disconnected.

In addition the diagnostic trouble code can also be erased by turning the ignition switch to ON and sending the diagnostic trouble code erase signal from the scan tool to the engine control module.

CAUTION: If a sensor connector is disconnected with the ignition switch turned on, the diagnostic trouble code is memorized. In this case, send the diagnostic trouble code erase signal from the scan tool to the engine control module or disconnect the battery terminal (-) for 10 seconds or more, and the diagnosis memory will be erased.

CAUTION: The diagnostic trouble code of ignition timing adjustment signal is outputted when terminal for ignition timing adjustment is short circuited. Therefore, it is not abnormal that the code is outputted even when terminal for ignition timing adjustment is short circuited at the time of ignition timing adjustment.