DTC P0601: Control Module Read Only Memory: Description
WARNING: This page is about a different car, the 2001 Cadillac Seville, 2001 Cadillac Eldorado, and 2001 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
Powertrain Control Module (PCM) uses an Electrically Erasable Programmable Read Only Memory (EEPROM) to store software and calibration information. PCM uses a checksum to verify integrity of the information. At time of programming, PCM calculates a checksum and stores the value in the EEPROM. With ignition on, PCM retrieves the information and performs a checsum. PCM compares the ignition on value to the value stored in the EEPROM. If checksum at ignition on does not match stored checksum, DTC P0601 will set.