Circuit Description
The powertrain control module (PCM) uses an electrically erasable programmable read only memory (EEPROM) to store software and calibration information. The PCM uses a checksum to verify the integrity of the information. At the time of programming, the PCM calculates a checksum and stores the value in the EEPROM. At key ON, the PCM retrieves the information and performs a checksum. The PCM compares the key ON value to the value stored in EEPROM. If the checksum at key ON does not match the stored checksum, DTC P0601 will set.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | DTC P0601 was not set previously. |
Conditions for Setting the DTC
The PCM detects a calculated checksum value that does not match the stored checksum 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/Failure 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.
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | ||
|
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- |
