Important Guidelines When Performing Test Procedures

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

When it is noticed that an irregularity has continued for a specified time or longer from when the irregular signal is initially monitored. Passing a certain number, the engine control unit judges that an irregularity has occurred, memorizes the trouble code and outputs the signal to the self-diagnosis output terminal.

There are 13 diagnosis items and the diagnosis results can be read out with a voltmeter.

Moreover, since memorization of the trouble codes is backed up directly by the battery, the diagnosis results are memorized even if the ignition key is turned off. The trouble codes will however, be erased when the battery terminal or the engine control unit connector is disconnected.

CAUTION: If the sensor connector is disconnected with the ignition switch turned on, the diagnosis code is memorized. In this case disconnect the battery terminal (-) for 10 seconds or more and the diagnosis memory will be erased.