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 P064C: Glow Plug Control Module Performance

### Circuit/System Description

This DTC applies to internal microprocessor integrity conditions within the glow plug control module.

### Conditions for Running the DTC

• | The ignition is ON.

• | The battery voltage is between 9-16 volts.

• | The DTC runs once per ignition cycle when the above condition is met.

### Conditions for Setting the DTC

The ECM detects a glow plug control module malfunction.

### Action Taken When the DTC Sets

DTC P064C is a Type C DTC.

### Conditions for Clearing the DTC

DTC P064C is a Type C DTC.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component 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

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition On, observe the DTC information with a scan tool. DTC P064C should not set.
2. 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.

### Circuit/System Testing

1. Ignition OFF, and the MAIN fuse removed, disconnect the harness connector at the glow plug control module.
2. Test for less than 5 ohms of resistance between the ground circuit terminal 7 and ground.

⇒ | If greater than the specified range, repair the ground circuit for an open/high resistance.

3. Test for greater than 1 ohm of resistance between each of the glow plug circuit terminals and ground.

• | Glow Plug 1 circuit terminal 4

• | Glow Plug 2 circuit terminal 3

• | Glow Plug 3 circuit terminal 2

• | Glow Plug 4 circuit terminal 1

⇒ | If less than the specified range, repair the glow plug circuit for a short to ground.

4. Install the MAIN fuse. Ignition ON, verify a test lamp illuminates between the ignition 1 voltage circuit terminal 6 and ground.

⇒ | If the test lamp does not illuminate, repair the ignition 1 voltage circuit for a short to ground or an open/high resistance.

5. If all circuits test normal, replace the glow plug control module.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.