P0601

CIRCUIT DESCRIPTION
The PCM uses an Electrically Erasable Programmable Read Only Memory (EEPROM) to store software and calibration information. The PCM uses a check sum to verify the integrity of the information. At the time of programming, the PCM calculates a check sum and stores the value in the EEPROM. At key ON, the PCM retrieves the information and performs a check sum. The PCM compares the key ON value to the value stored in EEPROM. If the check sum at key ON does not match the stored check sum, DTC P0601 will set.

CONDITIONS FOR RUNNING THE DTC
The ignition is ON.

CONDITIONS FOR SETTING THE DTC
The PCM detects a calculated check sum value that does not match the stored check sum value.

ACTION TAKEN WHEN THE DTC SETS
The PCM will illuminate the Malfunction Indicator Lamp (MIL) the first time the malfunction is detected.

The PCM will store conditions which were present when the DTC set as Freeze Frame and the Fail Records data.

DIAGNOSTIC AIDS
DTC P0601 indicates that the contents of the EEPROM have changed since the PCM was programmed. The PCM must be replaced. Remember to program the replacement PCM with the correct software and calibration for the vehicle.

If the condition is intermittent, refer to Intermittent Conditions in Symptoms. Intermittent Conditions

TEST DESCRIPTION

Steps 1 - 2:

The number below refers to the step number on the diagnostic table.
2. This DTC indicates an internal PCM malfunction.