Continuous Memory Self-Test

WARNING: This page is about a different car, the 2001 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Continuous memory self-test may also be known as memory test.

Continuous memory self-test is a functional test of PCM performed under any condition (engine running or engine off) with ignition switch turned to ON position. Unlike KOEO and KOER self-tests which can only be activated on demand, continuous memory is always active in monitoring the system. When a fault is detected, DTC will be stored in memory. This makes it possible to diagnose intermittent faults. Memory DTCs should be serviced last, after all other type of DTCs.

There are 2 types of Continuous Memory DTCs. Emission related DTCs will illuminate the Malfunction Indicator Light (MIL) on instrument cluster. Non-emission DTCs will never illuminate MIL. On emission-related MIL DTCs, PCM will store DTC in continuous memory at first detection of problem. The MIL will not be illuminated, but DTC is considered by PCM to be a pending DTC. If same problem is detected in next drive cycle, MIL will illuminate. MIL will go out if fault is not present after 3 consecutive drive cycles, or PCM has been reset. An emission-related pending DTC or non-emission DTC will be erased after 40-80 warm-up cycles or PCM reset.

The vehicle may need to be driven or the OBDII Drive Cycle completed to allow the PCM to detect a fault. See TRANSAXLE DRIVE CYCLE TEST under SELF-DIAGNOSTIC SYSTEM. When a fault is stored in memory, a DTC will be output on the data link at the end of the test when requested by a scan tool.