Technical Description of OBD-II Trouble Code
The circuit for the Generator Field/F Terminal is experiencing low voltage.
What does that mean?
This is a generic diagnostic trouble code (DTC) that is applicable to many OBD-II vehicles (1996-newer). This includes vehicles from Ford, Hyundai, Mercedes Benz, Sprinter, Land Rover, Kia, and others. While it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
A stored code P0625 indicates that the powertrain control module (PCM) has detected a voltage signal from the generator field coil circuit that is lower than expected. The “F” indicates that the field coil control circuit is at fault.
The field coil is easily recognizable by its windings, which can be seen through the vent holes on most alternators. The field coil surrounds the generator armature and remains stationary in the alternator housing. The armature spins inside the energized field coil, which is powered by the battery voltage. Each time the engine is started, the field coil is energized.
The PCM continuously monitors the continuity and voltage level of the generator field circuit while the engine is running. The generator field coil is essential for the operation of the generator and for maintaining battery charge levels.
If a problem is detected in monitoring the generator field circuit, a code P0625 will be stored and a malfunction indicator lamp (MIL) may illuminate. Depending on the perceived severity of the malfunction, multiple failure cycles may be required for the MIL to illuminate.
A typical alternator:
What is the severity of this DTC?
A stored code P0625 could result in various drivability concerns, including a no-start condition and/or a dead battery. It should be considered severe.
What are some of the symptoms of the code?
Symptoms of a P0625 trouble code may include:
What are some of the common causes of the code?
Possible causes for this code may include:
What are some P0625 troubleshooting steps?
To diagnose a code P0625, you will need a diagnostic scanner, a battery/alternator tester, 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 important to write down this information in case the code is intermittent. After recording the necessary information, clear the codes and 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. In some cases, the condition that caused the P0625 code to be stored may need to worsen before a diagnosis can be made. If the code is reset, continue with the diagnosis.
Use the battery/alternator tester to load-test the battery and ensure that it is adequately charged. If the battery is not charged, follow the recommended charging procedure and test the alternator/generator. Follow the manufacturer’s specifications for minimum and maximum voltage output requirements for the battery and alternator. If the alternator/generator is not charging, proceed to the next step in the diagnosis.
Refer to 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 alternator/generator field 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 voltage is present at the generator field coil control terminal, suspect a defective alternator/generator.
