For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC P0601: Control Module Read Only Memory (ROM)
DTC P0602: Control Module Not Programmed
DTC P0603: Control Module Long Term Memory Reset
DTC P0604: Control Module Random Access Memory (RAM)
DTC P0606: Control Module Internal Performance
DTC P2610: Control Module Ignition Off Timer Performance

### Circuit/System Description

This diagnostic applies to internal microprocessor integrity conditions within the engine control module (ECM). This diagnostic also addresses if the ECM is not programmed.

### Conditions for Running the DTC

#### P0601

The checksum calculation at power down in the last drive cycle completely finished. DTC P0601 runs once an ignition cycle for 30 seconds.

#### P0602

The ignition is ON, with the engine OFF. DTC P0602 runs continuously when the ignition is ON for more than 1 second.

#### P0603

The throttle actuator control (TAC) power down calculation in the last drive cycle was completely finished. DTC P0603 runs once an ignition cycle for 5 seconds.

#### P0604

The read/write test at power down in the last drive cycle completely finished. DTC P0604 runs once an ignition cycle for 5 seconds.

#### P0606

The power down calculation in the last drive cycle was completely finished. DTC P0606 runs continuously with ignition ON or engine operating for more than 5 seconds.

#### P2610

DTC P2610 runs continuously once the engine is operating and the real time clock is active.

### Conditions for Setting the DTC

#### P0601

The ECM detects the incorrect read only memory (ROM) checksum for more than 4 seconds.

#### P0602

The ECM detects that programming is incomplete for more than 4 seconds.

#### P0603

The ECM detects an error during the shut down path test.

#### P0604

The ECM detects random access memory (RAM) errors.

#### P0606

The ECM detects an internal condition for more than 4 seconds or for a cumulative of 50 seconds.

#### P2610

The ECM detects the engine off timer is not valid for more than 4 seconds or for a cumulative of 50 seconds.

### Action Taken When the DTC Sets

• | DTCs P0601, P0602, P0603, P0604, and P0606 are Type A DTCs.

• | DTC P2610 is a Type B DTC.

### Conditions for Clearing the DTC

• | DTCs P0601, P0602, P0603, P0604, and P0606 are Type A DTCs.

• | DTC P2610 is a Type B DTC.

### Reference Information

#### Description and Operation

Engine Control Module Description

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

### Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. DTC P0602 or P0606 should not set.

⇒ | If DTC P0602 failed this ignition, program the ECM. If the DTC resets, replace the ECM.

⇒ | If DTC P0606 failed this ignition, clear the DTCs with a scan tool and verify the DTC does not reset. If DTC resets, replace the ECM.

Important: A low battery condition can cause DTC P0603 to set. Verify the starting and charging system is in good condition when diagnosing DTC P0603. Refer to Charging System Test .

2. Observe the DTC information with a scan tool. DTC P0601, P0603, P0604, or P2610 should not set.

⇒ | If a DTC failed this ignition, replace the ECM.

3. Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that you observed in the Freeze Frame/Failure Records data.

### Repair Instructions

• | Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Control Module References for engine control module replacement, setup, and programming