Circuit Description

Input and output devices in the PCM include analog-to-digital converters, signal buffers, counters and special drivers. PCM controls most components with electronic switches which complete a ground circuit when switched On. Switches are arranged in groups of 4 and 7 called surface-mounted Quad Driver Modules (QDM), which independently control 4 or 7 outputs.

When DTC sets, PCM will not illuminate MIL. PCM will store conditions present when DTC was set as FAILURE RECORDS data only.

PCM will turn MIL off on third consecutive trip cycle during which diagnostic runs and fault is no longer recognized. A history DTC will clear after 40 consecutive trip cycles during which diagnostic runs and fault is no longer recognized. DTC can be cleared with scan tool, or by disconnecting battery voltage feed to PCM.