System Description

Scan Tool:

DESCRIPTION
The Engine Control Module (ECM) monitors the input/output signals (some signals at all times and the others under specified conditions) to the ECM. When it is noticed that an irregularity has continued for a specified length of time, the ECM judges that an irregularity has occurred, sets the Diagnostic Trouble Code (DTC) into memory, and outputs the signal to the diagnostic output terminal.

There are 50 DTC's, including the normal state, which can be read out with a scan tool.

Since memorization of the DTC's is backed up directly by the battery, the codes are not erased if the ignition key is turned "OFF". The diagnostic trouble codes will, however, be erased when the battery terminal or the ECM connector is disconnected.

In addition, the DTC 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 ECM.

CAUTION: If a sensor connector is disconnected with the ignition switch turned "ON", the DTC is memorized. In this case, send the diagnostic trouble code erase signal from the scan tool to the engine control module and the diagnostic memory will be erased.

If there are multiple DTC's, they will be indicated sequentially from the smallest code number to the largest.

CAUTION: The trouble code for ignition timing adjustment is usually set when the ignition timing adjustment terminal is grounded. Therefore, it is necessary to clear the trouble code from memory after the timing has been adjusted.