P0625 Generator Field / F Terminal Circuit Low

OBD-II Trouble Code - P0625 - Data Sheet

P0625 - Low signal in the generator field terminal F circuit

What does trouble code P0625 mean?

This is a generic Diagnostic Trouble Code (DTC) applicable to many OBD-II vehicles (1996 and newer). This may include, but is not limited to, Ford, Hyundai, Mercedes Benz, Sprinter, Land Rover, Kia, etc. Despite the general nature, the exact repair steps may vary depending on the model year, make, model and transmission configuration. ...

A stored P0625 code means the powertrain control module (PCM) has detected a voltage signal lower than expected from the generator field coil circuit. The letter F simply repeats that the field coil control circuit is faulty.

The field coil is probably best recognized by its windings, which are visible through the vents on most alternators. The excitation coil surrounds the generator armature and remains stationary in the generator housing. The armature rotates inside an excitation coil, which is powered by battery voltage. Every time the engine is started, the field coil is energized.

The PCM monitors the continuity and voltage level of the generator excitation circuit whenever the engine is running. The generator field coil is integral to the operation of the generator and the maintenance of the battery level.

If a problem is detected while monitoring the generator excitation circuit, a P0625 code 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 to illuminate the MIL.

Typical alternator:

What is the severity of this DTC?

A stored P0625 code can result in a variety of handling problems including no starting and / or low battery. It should be classified as heavy.

What are some symptoms of code P0625?

Symptoms that indicate that a P0625 code has been stored include difficult time shifting. The engine may even stall, or you may find that it starts to vibrate or make strange noises when you are idling.

The battery may also be drained. There are a number of other handling issues that will also tell you something is wrong. Acceleration is usually difficult after this code has been stored and fuel efficiency is likely to suffer as a result.

If the module that intercepts it needs multiple occurrences before saving the code, it can still record a wait for the original.

Symptoms of a P0625 trouble code may include:

• Charging lamp illumination
• Engine control problems
• Unintentional engine shutdown
• Engine start delay
• Other stored codes

What are some of the common causes for the code?

The P0625 code is unique in that, unlike most other PCM codes, it is usually caused by a faulty alternator or a problem with the generator control module. Many of the generator control circuits are integrated into the PCM.

Reasons for this code may include:

• Open or short circuit in the generator field control circuit
• Blown fuse or blown fuse
• Defective generator / generator
• Defective PCM
• PCM programming error
• Faulty CAN bus
• Loose control module ground strap
• Damaged or broken ground wire

What are some steps to troubleshoot the P0625?

Diagnosing the P0625 code requires a diagnostic scanner, battery / alternator tester, digital volt / ohmmeter (DVOM), and a reliable vehicle information source.

Consult your vehicle information source for technical service bulletins (TSBs) that reproduce the stored code, vehicle (year, make, model and engine) and symptoms detected. If you find a suitable TSB, it can provide useful diagnostics.

Start by connecting the scanner to the vehicle's diagnostic port and retrieving all stored codes and freeze frame data. You will want to write this information down just in case the code turns out to be intermittent. After recording all relevant information, clear the codes and test drive the vehicle until the code is cleared or the PCM enters standby mode. If the PCM enters ready mode, the code is intermittent and harder to diagnose. The condition for which the P0625 was stored may even get worse before a diagnosis can be made. If the code is cleared, continue diagnostics.

Use a battery / alternator tester to test the battery under load and make sure it is sufficiently charged. If not, charge the battery as recommended and check the alternator / generator. Follow the manufacturer's recommended specifications for minimum and maximum output voltage requirements for battery and alternator. If the alternator / generator does not charge, proceed to the next diagnostic step.

Use your vehicle information source to obtain connector views, connector pinouts, component locators, wiring diagrams, and diagnostic block diagrams relevant to the code and vehicle in question.

Check for battery voltage on the alternator / alternator control circuit using the appropriate wiring diagram and your DVOM. If not, check system fuses and relays and replace defective parts if necessary. If voltage is detected at the generator excitation coil control terminal, suspect that the generator / generator is faulty.

• The excitation coil is an integral part of the generator and usually cannot be replaced separately.

COMMON ERRORS WHEN DIAGNOSING CODE P0625

This code can represent many different underlying communication problems. Unfortunately, the symptoms are often misdiagnosed as the problem and the essence of the repair. This leaves the main problem unresolved. Diagnosis and recovery of codes in the order in which they were saved. The use of still image data will help with this.

HOW SERIOUS CODE P0625 IS?

The crux of the problem concerns CAN. Simply put, CAN controls almost every electrical function in your vehicle. The PCM serves as the main controller. So if you continue this problem, it's only a matter of time before more and more symptoms appear.

WHAT REPAIRS CAN FIX CODE P0625?

The exact steps your mechanic will take will depend on the specifics of the saved codes. However, you will most likely

• Replace damaged electrical components (including blown fuses)
• Replacing the Control Module Grounding Wristband
• Disconnect all CAN pins to test them (this is time consuming and can be very expensive so should be the last step)

ADDITIONAL COMMENTS REGARDING CODE P0625 CONSIDERATION

Remember that after every repair, you need to reset the system to see if there are other issues. Everything that happens with CAN can lead to a number of other problems.

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Need more help with the P0625 code?

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NOTE. This information is provided for informational purposes only. It is not intended to be used as a repair recommendation and we are not responsible for any action you take on any vehicle. All information on this site is protected by copyright.