For 1990-2009 cars

### Circuit Description

The powertrain control module (PCM) used in this vehicle utilizes an electrically erasable programmable read only memory (EEPROM). The EEPROM contains program information and the calibrations required for engine, transaxle, and powertrain diagnostics operation.

The EEPROM is not replaceable. When the PCM is replaced or a calibration update is required, the PCM must be programmed using a scan tool or approved Techline equipment. Refer to Powertrain Control Module Programming .

### Condition for Setting the DTC

The PCM detects an internal program fault (check sum error).

### Action Taken When the DTC Sets

• | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.

• | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

### Conditions for Clearing the MIL/DTC

• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• | Clear the MIL and the DTC with a scan tool.

### Diagnostic Aids

DTC P0601 indicates that the contents of the EEPROM have changed since the PCM was programmed. The only possible repair is PCM replacement. Remember to program the replacement PCM with the correct software and calibration for the vehicle. Refer to Powertrain Control Module Programming .

Step | Action | Yes | No
--- | --- | --- | ---
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | Go to Diagnostic System Check - Engine Controls
2 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | Go to Diagnostic System Check - Engine Controls | --