Error Code P064B is defined as PTO Control Module. This is a generic trouble code, meaning it applies to all vehicles equipped with the OBD-II system. This includes vehicle models from Chrysler, Ford, GMC, Mercedes Benz, etc. Specifications on the definition, troubleshooting, and repairs, of course, vary from make, model, and powertrain configuration.
The job of the PTO (power take off) control module is to initiate various functions of the PTO. This includes activation of the specified lighting, an increase of engine RPM (when PTO is engaged), and disengagement of drive wheels (using transfer case). For most cases, the PTO controller is integrated right into the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes). For some vehicles, it’s a stand-alone module.
This feature is included on many hydraulically operated service vehicles, such as dump body rucks and wreckers. This allows a large hydraulic pump to be driven using the engine’s power. 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 through an auxiliary drive shaft. This a very durable system and provides a lot of power for heavy-duty functions, such as dumping heavy materials (for dump body) or lifting other vehicles (wrecker). The PTO system is also used in many specialized applications.
Whenever the ignition is turned on, and the PCM is energized, various controller self-tests are simultaneously performed. Aside from running internal controller self-test, the CAN (controller area network) carries serial data from each module to make sure the onboard controllers are interfacing correctly.
If the PCM sees a problem in monitoring the PTO control module, it will store the Error Code P064B and activate the Check Engine light, as it indicates a malfunction in the Power Take Off control module.
- Malfunctioning or completely inoperative PTO
- Slow and hard starting
- Engine stall at startup
- Engine drivability issues
Other codes may be stored as well.
Common causes for this code include:
- Defective PTO controller
- Faulty or programming error in PCM
- Open or short in PTO control circuit
How to Check
Checking this code requires a DVOM (digital volt ohmmeter), dependable vehicle information for TSB (technical service bulletin) that has the code stored, vehicle (year, make, model, engine), and exhibited symptoms. Finding the right TSB can lead you to more easy and successful diagnostic and repair procedure.
Start by connecting the scanner to the vehicle diagnostic port. Retrieve all the stored data including freeze frame data. Write down this information. Then, clear the codes and then take the vehicle for a test drive until the code reset, or the PCM enter readiness mode.
If the PCM enters readiness mode, that means the problem is intermittent. You may have to wait for the problem to get worse before you can successfully diagnose and repair. If the code resets on the other hand, then continue with the diagnosis.
Use the vehicle information to know the connector pin-out charts, face views, component locators, wiring diagrams, and diagnostic flow charts of the vehicle.
Use the diagram and DVOM to check the voltage of the battery on the PTO control circuit. If there’s none, check the system fuses and relays. Replace the defective parts as necessary.
If there is no voltage (and ground) on the PTO control circuit (and all fuses and relays look to be working correctly), inspect the controller related wiring and harness. Check the chassis and engine ground junctions. Use the vehicle information source to get a ground location for related circuits.
If there is voltage (and ground) present on the PTO control circuit, then check system controllers and look for signs of damage, water intrusion, heat, or collision damage. Damaged controllers, especially those damaged by water, are considered defective and must be replaced.
If the controller power and ground circuits are in good shape, then you can suspect a defective controller or a programming error. In which case, controller replacement will be required, as well as reprogramming.
In some cases, you may want to purchase a re-programmed controller from aftermarket sources. Other vehicles/controllers require onboard reprogramming that may be done through a dealership, or by a qualified technician.
How to Fix
- Replace defective PTO control circuit
- Replacement of damaged or corroded wiring and related electrical connectors
- Repair or replacement of damaged terminals (straighten bent pins)
- Replacement of burnt out fuse(s)
It’s important to test the integrity of the controller ground by connecting its negative test lead of the DVOM to ground, and a positive test lead to the battery voltage.