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 P0603: Control Module Long Term Memory Reset
DTC P0604: Control Module Random Access Memory Performance
DTC P0605: Control Module Programming Read Only Memory Performance
DTC P0606: Control Module Processor Performance
DTC P167D: Control Module Ignition Coil Internal Circuit

### Circuit/System Description

This diagnostic applies to internal microprocessor integrity conditions within the engine control module (ECM).

### Conditions for Running the DTC

#### P0603

• | The ignition is ON.

• | The power down calculation in the last drive cycle was completely finished.

• | DTC P0603 runs continuously once the conditions above have been met for greater than 5 seconds.

#### P0604

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

#### P0605

The checksum calculation at power down in the last drive cycle was completely finished. DTC P0605 runs once an ignition cycle when the condition is met for 30 seconds at ignition OFF.

#### P0606

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

#### P167D

• | The engine is operating.

• | The ignition voltage is between 9-18 volts.

• | The engine speed is less than 6,000 RPM.

• | DTC P167D runs continuously once the conditions above are met.

### Conditions for Setting the DTC

#### P0603

The ECM detects an error during the shut down path test for 1 second or a cumulative of 10 seconds.

#### P0604

The ECM detects random access memory (RAM) errors for greater than 1 second.

#### P0605

The ECM detects the incorrect read only memory (ROM) checksum for greater than 1 second.

#### P0606

The ECM detects an internal software error with in the throttle actuated control (TAC) system for greater than 1 second, or a cumulative of 10 seconds.

#### P167D

The ECM detects a condition with the integrated circuits of the ignition driver module for greater than 4 seconds, or a cumulative of 30 seconds.

### Action Taken When the DTC Sets

• | DTCs P0603, P0604, P0605, and P0606 are Type A DTCs.

• | DTC P167D is a Type B DTC.

### Conditions for Clearing the DTC

• | DTCs P0603, P0604, P0605, and P0606 are Type A DTCs.

• | DTC P167D 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 P0606 should not set.

⇒ | 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 K20 ECM.

2. Observe the DTC information with a scan tool. DTC P0603, P0604, P0605, or P167D should not set.

⇒ | If a DTC failed this ignition, replace the K20 ECM.

3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from 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