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 Descriptor

DTC C1550 36: ECU Failure EEPROM failure
DTC C1550 37: ECU Failure watchdog/safety failure
DTC C1550 38: ECU Failure supervision software failure
DTC C1550 39: ECU Failure internal electronic failure
DTC C1550 3A: ECU Failure incorrect component installed

### Circuit/System Description

### Conditions for Running the DTC

#### DTC C1550 38

Engine starting

#### DTC C1550 36

Engine running

#### DTC C1550 39

• | Engine starting

• | Engine running

### Conditions for Setting the DTC

#### DTC C1550 36, 38, 39

• | Control unit software/hardware failure.

• | Above condition must be fulfilled for at least 0 seconds.

### Action Taken When the DTC Sets

#### DTC C1550 36

No steering boost function

#### DTC C1550 38

The system function is not affected.

#### DTC C1550 39

• | The steering boost is switched off.

• | The system function is not affected.

### Conditions for Clearing the DTC

A history DTC will clear after 60 consecutive malfunction-free ignition cycles.

### Reference Information

#### Schematic Reference

Power Steering Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Power Steering System Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Verification

1. Verify that DTC C1550 is not set.

⇒ | If the DTC is set, reprogram the PSCM. If the DTC resets, replace the PSCM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.