Technical Description of OBD-II Trouble Code
PTO 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, 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 P064B indicates that the powertrain control module (PCM) has detected a malfunction in the power take off (PTO) control module.
The PTO control module is responsible for initiating various PTO functions. These functions may include activating specified lighting, increasing engine RPM (when the PTO is engaged), and disengaging the drive wheels (using the transfer case). In most cases, the PTO controller is integrated into the PCM, but it can also be a stand-alone module.
The PTO is a feature found in many hydraulically operated service vehicles such as wreckers and dump body trucks. It allows a large hydraulic pump to be driven using power from the engine. With the vehicle parked and the engine at idle, a transfer case on the transmission output shaft allows the drive wheels to be disengaged and the pump to be engaged via an auxiliary drive shaft. This system is quite durable and provides ample power for heavy-duty functions such as lifting another vehicle (wrecker) or dumping heavy materials (dump body). There are many specialized applications that utilize a PTO system besides just wreckers and dump trucks.
Each time the ignition is turned on and the PCM is energized, multiple controller self-tests are performed. By performing these self-tests, the PCM can monitor serial data carried over the controller area network (CAN) to ensure that on-board controllers are interfacing properly.
If a problem is detected in monitoring the PTO control module, a code P064B will be stored and a malfunction indicator lamp (MIL) may illuminate.
What is the severity of this DTC?
For safety reasons, PTO control module codes should be taken seriously. A stored code P064B could result in a lack of PTO function and may pose serious safety hazards.
What are some of the symptoms of the code?
Symptoms of a P064B trouble code may include:
What are some of the common causes of the code?
Possible causes for this code may include:
What are some P064B troubleshooting steps?
To diagnose a code P064B, 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 the 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 proves to be 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 will be more challenging to diagnose. The condition that caused the P064B to be stored may need to worsen before an accurate diagnosis can be made. If the code is reset, continue with your 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 PTO control circuit by referring to the appropriate wiring diagram and using 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 PTO control circuit (and all fuses and relays appear to be functioning properly), inspect the controller-related wiring and harnesses. Also, check the chassis and engine ground junctions. Use your vehicle information source to find the ground locations for related circuits.
If there is voltage (and ground) present on the PTO control circuit, inspect the system controllers for signs of water, heat, or collision damage. Any damaged controller, particularly due to water, should be considered defective.
If the controller power and ground circuits are intact, suspect a defective controller or a controller programming error. Controller replacement will require reprogramming.
