P065A: Generator System Performance

What Does The P065A Code Mean?

A stored code P065A means 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 called the generator but more frequently this type of code is used in a hybrid or electric vehicle which generates electrical power from a generator. The generator may be driven by the engine or any of the drive wheels.

The PCM monitors generator output voltage and amperage at varying RPM levels and load degrees and calculates voltage requirements accordingly. In addition to monitoring generator output (performance), the PCM is also responsible for providing a signal that activates the generator lamp in the event of low output.

If a problem is detected in monitoring generator performance, a code P065A will be stored and a malfunction indicator lamp (MIL) may be illuminated.

What Are The Symptoms Of The P065A Code?

Symptoms of a P065A trouble code may include:

• Delayed or no start
• Electrical accessories may be inoperative
• Engine drivability issues

What Are The Potential Causes Of The P065A Code?

Causes for this code may include:

• Defective generator
• Bad fuse, relay, or fusible link
• Open or shorted circuit between the PCM and generator
• PCM programming error
• Faulty controller or PCM

How Serious Is This P065A Code?

A P065A should be categorized as severe because it may result in a low battery charge level and/or a no start condition.

How Can You Fix The P065A Code?

The battery must be fully charged and the generator operating at an acceptable level before attempting to diagnose a P065A.

Consult your vehicle information source for technical service bulletins (TSB) that replicate the code stored, vehicle (year, make, model, and engine), and symptoms exhibited. If you find the appropriate TSB, it may yield helpful diagnostic information.

A diagnostic scanner and a digital volt/ohmmeter will be necessary to accurately diagnose a code P065A. A reliable source of vehicle information will also be required.

Retrieve All Stored Codes

Begin by connecting the scanner to the vehicle diagnostic port and retrieving all stored codes and freeze frame data. You will want to write this information down, just in case the code proves to be an intermittent one.

Clear The Codes And Test Drive

After recording all pertinent information, clear the codes and test drive the vehicle (if possible) 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 difficult to diagnose. The condition, which caused the P065A to be stored, may need to worsen before an accurate diagnosis can be reached. On the other hand, if the code fails to reset and there are no drivability symptoms exhibited, the vehicle can be operated normally.

Visually Inspect The Related Wiring And Harnesses

If the P065A is immediately reset, proceed with a visual inspection of system related wiring and connectors. Harnesses that have been broken of unplugged should be repaired or replaced as required.

If wiring and connectors appear functional, use your source of vehicle information 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 make sure the generator is being supplied 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 defective fuses, relays, or fusible links as required. In some cases generator supply voltage is routed through the PCM. You may use wiring diagrams and other vehicle specific information to help diagnose generator voltage supply malfunctions.

Use Your DVOM To Test Generator Output Performance

If generator supply voltage is present, use your DVOM to test generator output performance at the appropriate pin of the generator connector. If the appropriate level of generator output voltage is not discovered, suspect that the generator is defective.

If the generator is charging within specifications, check the level of voltage at the appropriate pin of the PCM connector. If the voltage is the same at the PCM connector as it is at the generator, suspect that the PCM is defective or there is a programming error.

Should the level of voltage at the PCM connector differ (by more than 10-percent) between what is detected at the generator connector, suspect a shorted or open circuit between the two.

• Generator fuses should be tested with the circuit loaded to avoid a misdiagnosis

Recommended Parts

Below are some recommended auto parts to help you address the trouble code affecting your vehicle and get it running smoothly again:

>>> Alternator
>>> CrocSee 250 Pieces - Car Fuses Assortment Kit
>>> ECU
>>> INNOVA 5210
>>> KAIWEETS Digital Multimeter

Note: During the purchasing process, please check carefully whether the part you want to buy fits your car!

Reference Sources

P065A Generator System Performance, OBD-Codes.