For diagnostic testing procedures, see DIAGNOSTIC TESTS in CRUISE CONTROL SYSTEMS article.
Circuit Description
PCM 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 PCM is replaced or update calibration is required, PCM must be reprogrammed using scan tool. See EEPROM PROGRAMMING PROCEDURE under PROGRAMMING. Conditions for setting DTC
- PCM detects an internal program fault (check sum error).
Diagnostic Aids
DTC P0601 indicates that contents of EEPROM have changed since PCM was programmed. Only repair is PCM replacement. Ensure replacement PCM is reprogrammed using correct software and calibration for vehicle. See EEPROM PROGRAMMING PROCEDURE under PROGRAMMING.