On-Board Diagnostics

A/T DIAGNOSTIC TROUBLE CODE DIAGNOSIS
ON-BOARD DIAGNOSTICS
The Powertrain Control Module (PCM) monitors its input/output signals (some signals all time and others under specified conditions). When an irregular signal is initially monitored, the PCM decides that a malfunction has occurred. There are 25 diagnostic items. The diagnostic results can be read with a scan tool. Diagnostic trouble codes are kept in memory by direct battery feed. The codes are retained in memory if the ignition switch is "LOCK" (OFF).
Diagnostic trouble codes will, however, be erased when a battery terminal or the PCM connector is disconnected. In addition, the diagnostic trouble code can also be erased by the scan tool MUT-II (MB991502).

NOTE: If a sensor is disconnected with the ignition switch is "ON" a diagnostic trouble code is memorized. In this case, erase the DTC using the scan tool. The 25 diagnostic items are all indicated sequentially from the smallest code number.