Technical Description of OBD-II Trouble Code
Glow Plug Control Module
What does that signify?
This is a generic diagnostic trouble code (DTC) that is applicable to many OBD-II vehicles (1996-newer). This includes vehicles from Chrysler, Ford, General Motors, Mercedes-Benz, Nissan, Toyota, and others. While it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration.
A stored code P064C indicates that the powertrain control module (PCM) has detected a malfunction in the glow plug control module.
The glow plug control module is responsible for initiating the glow plug preheater timer and the glow plug for each individual cylinder. Glow plugs, the glow plug timer, and the glow plug controller are exclusively used in vehicles with diesel propulsion systems.
The glow plug control module may exist as a stand-alone module, but it is most commonly integrated into the PCM.
Every time the ignition is turned on and the PCM is powered, multiple controller self-tests are conducted. By performing these self-tests, the PCM can monitor serial data transmitted over the controller area network (CAN) to ensure proper interaction with on-board controllers.
If a problem is detected in monitoring the glow plug control module, a code P064C will be stored and a malfunction indicator lamp (MIL) may illuminate.
A typical glow plug:
What is the severity of this DTC?
Glow plug control module codes may result in the loss of glow plug function and can cause an engine no-start condition. The code P064C should be considered severe.
What are some of the symptoms of the code?
Symptoms of a P064C trouble code may include:
What are some of the common causes of the code?
Possible causes for this code may include:
What are some P064C troubleshooting steps?
To diagnose a code P064C, you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information.
Refer to your vehicle information source for technical service bulletins (TSB) that match the stored code, vehicle details (year, make, model, and engine), and exhibited symptoms. If you find a relevant TSB, it may provide helpful diagnostic information.
Start by connecting the scanner to the vehicle diagnostic port and retrieving all stored codes and freeze frame data. It is advisable to write down this information in case the code is intermittent. After recording all relevant information, clear the codes and, if possible, test drive the vehicle until the code is reset or the PCM enters readiness mode.
If the PCM enters readiness mode, the code is intermittent and diagnosing it will be more challenging. The condition that caused the P064C to be stored may need to worsen before an accurate diagnosis can be made. If the code is reset, continue with the diagnosis.
Use your source of vehicle information to obtain connector face views, connector pin-out charts, component locators, wiring diagrams, and diagnostic flow charts related to the code and the specific vehicle.
Check if there is battery voltage on the glow plug control circuit using the appropriate wiring diagram and your DVOM. If there is no voltage, check the system fuses and relays and replace any defective parts as necessary.
If there is no voltage (and/or ground) on the glow plug control circuit (and all fuses and relays appear to be functioning properly), inspect the wiring and harnesses related to the controller. Also, check the chassis and engine ground junctions. Use your vehicle information source to find the ground locations for the relevant circuits.
If there is voltage (and ground) present on the glow plug control circuit, inspect the system controllers for signs of water, heat, or collision damage. Any damaged controller, particularly due to water exposure, should be considered defective.
If the controller power and ground circuits are intact, suspect a defective controller or a controller programming error. Replacing the controller will require reprogramming.
