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 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) and the throttle actuator control (TAC) system. This diagnostic also addresses if the ECM is not programmed.

### Conditions for Running the DTC

#### P0601, P0602, and P0604

• | The ignition is ON, or the engine is operating.

• | The DTCs run once an ignition cycle.

#### P0606

• | The ignition is ON, or the engine is operating.

• | The ignition voltage is between 9-18 volts for Euro III emissions or greater than 11 volts for Euro IV emissions.

• | The DTC runs continuous once the above conditions are met.

#### P2610

• | The engine is running for at least 10 seconds.

• | The ignition voltage is greater than 11 volts.

• | The DTC runs once an ignition cycle.

### Conditions for Setting the DTC

#### P0601

The ECM detects that the checksum calculation does not match the expected checksum.

#### P0602

The controller is identified as a service replacement ECM.

#### P0604 or P0606

The ECM detects an internal condition for more than 3 seconds.

#### P2610

The ECM detects an error with the Ignition OFF timer.

### Action Taken When the DTC Sets

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

• | DTC P2610 is a type B DTC.

• | The ECM will disable engine operation or command the TAC system to operate in a Reduced Engine Power mode.

• | The ECM commands the reduced engine power indicator ON.

### Conditions for Clearing the DTC

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

• | DTC P2610 is a type B DTC.

### Diagnostic Aids

• | A low battery condition may cause DTC P2610 to set.

• | An intermittent condition at the ignition switch may cause DTC P2610 to set.

### Reference Information

#### Description and Operation

Engine Control Module Description

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

• | Engine Control Module Connector End Views

• | Engine Controls Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

### Circuit/System Testing

1. Ignition ON, clear the DTC information with a scan tool. Observe the scan tool DTC information. Verify that DTCs P0602, or P2610 do not fail this ignition cycle.

⇒ | If DTC P0602 failed this ignition, reprogram the ECM. Refer to Control Module References . If DTC P0602 resets, replace the ECM.

⇒ | If DTC P2610 failed this ignition, test the ECM ignition 1, and battery positive voltage circuits, for an open/high resistance or a short to ground. If the circuits test OK, replace the ECM.

2. Observe the DTC information with a scan tool. Verify that DTCs P0601, P0604, or P0606 do not set this ignition cycle.

⇒ | If any of the DTCs P0601, P0604, or P0606 are set this ignition cycle, replace the ECM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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