Technical Description of OBD-II Trouble Code
Performance of the Generator System
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 Land Rover, Honda, Jeep, Subaru, VW, Ford, Chrysler, 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 P065A indicates that the powertrain control module (PCM), or one of the other related controllers, has detected a low output condition in the generator system.
In some cases, the alternator is referred to as the generator, but this type of code is more commonly used in hybrid or electric vehicles that generate electrical power from a generator. The generator may be driven by the engine or any of the drive wheels.
The PCM monitors the generator’s output voltage and amperage at different RPM levels and load degrees, and calculates the voltage requirements accordingly. In addition to monitoring the generator’s output performance, the PCM is also responsible for activating the generator lamp if there is low output.
If a problem is detected in monitoring the generator’s performance, a code P065A will be stored and a malfunction indicator lamp (MIL) may illuminate.
Example of an alternator (generator):
What is the severity of this DTC?
A P065A should be considered severe because it can result in a low battery charge level and/or a no start condition.
What are some of the symptoms of the code?
Symptoms of a P065A trouble code may include:
What are some of the common causes of the code?
Possible causes for this code may include:
What are some P065A troubleshooting steps?
Before attempting to diagnose a P065A, ensure that the battery is fully charged and the generator is operating at an acceptable level.
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.
To accurately diagnose a code P065A, you will need a diagnostic scanner and a digital volt/ohmmeter. You will also require a reliable source of vehicle information.
Start by connecting the scanner to the vehicle’s 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 will be even more challenging to diagnose. The condition that caused the P065A to be stored may need to worsen before an accurate diagnosis can be made. However, if the code fails to reset and there are no drivability symptoms, the vehicle can be operated normally.
If the P065A is immediately reset, conduct a visual inspection of the system’s wiring and connectors. Repair or replace any broken or unplugged harnesses as necessary.
If the wiring and connectors appear to be functional, refer to your vehicle information source to obtain the appropriate wiring diagrams, connector face views, connector pin-out charts, and diagnostic flow charts.
Once you have the correct information, test all system fuses and relays to ensure that the generator is receiving voltage.
If generator supply voltage is not present, trace the appropriate circuit back to the fuse or relay from which it originates. Repair or replace any defective fuses, relays, or fusible links as necessary. In some cases, generator supply voltage may pass through the PCM. You can use wiring diagrams and other vehicle-specific information to help diagnose generator voltage supply malfunctions.
If generator supply voltage is present, use your DVOM to test the generator’s output performance at the appropriate pin of the generator connector. If the generator does not produce the expected level of output voltage, suspect that the generator is defective.
If the generator is charging within specifications, check the voltage level at the appropriate pin of the PCM connector. If the voltage at the PCM connector matches the voltage at the generator connector, suspect that the PCM is defective or there is a programming error.
If the voltage at the PCM connector differs from the voltage at the generator connector by more than 10 percent, suspect a shorted or open circuit between the two.
