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 P050B: Ignition Timing Performance

### Circuit/System Description

The engine control module (ECM) continuously compares the commanded spark timing to the actual spark timing. The ECM uses the crankshaft position (CKP) sensor and the camshaft position (CMP) sensor in order to calculate the actual spark timing.

### Conditions for Running the DTC

• | DTCs P0300, P0301, P0302, P0303, P0304, P0335, P0336, P0351, P0352, P0353, and P0354 are not set.

• | The engine is operating.

• | The engine speed is steady.

• | The ignition voltage is between 11-16 volts.

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

### Conditions for Setting the DTC

• | The ECM detects the difference between the actual spark and the commanded spark is greater than 5 degrees.

• | The condition exists for greater than 7 seconds.

### Action Taken When the DTC Sets

DTC P050B is a Type B DTC.

### Conditions for Clearing the DTC

DTC P050B 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 Testing

1. Engine running, observe the DTC information with a scan tool. DTCs P0016, P0324, P0325, or P0340 should not set.

⇒ | If any DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

2. Observe the DTC information with a scan tool. DTC P050B should not set.

⇒ | If DTC P050B is set, replace the ECM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming