Circuit Description

ECM uses an Electronically Erasable Programmable Read-Only Memory (EEPROM). EEPROM contains program information and calibration required for engine, transmission and powertrain diagnostics operation. Unlike proms used in past applications, EEPROM is not replaceable. When ECM is replaced or update calibration is required, ECM must be reprogrammed using scan tool. See EEPROM PROGRAMMING PROCEDURE  under POWERTRAIN CONTROL MODULE.

When DTC sets, ECM illuminates MIL as soon as fault was detected. ECM will store conditions present when DTC was set as freeze frame data in the FAILURE RECORDS data.

ECM 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 ECM.