For 1990-2009 cars

### Circuit Description

The 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.

Unlike the PROM used in past applications, 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 Replacement/Programming .

### Condition for Setting the DTC

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

### Action Taken When the DTC Sets

• | The PCM will illuminate the malfunction indicator lamp (MIL) during the first trip in which the diagnostic runs and fails.

• | If equipped with traction control, the PCM will command the EBTCM via the serial data circuit to turn OFF traction control and illuminate the TRACTION OFF lamp.

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

### Conditions for Clearing the MIL/DTC

• | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.

• | The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• | The DTC can be cleared by using the 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 Replacement/Programming .

1. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain OBD System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Replace the PCM. Important: : Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check | --