P0622 Generator Field F Control Circuit Malfunction

OBD-II Trouble Code - P0622 - Data Sheet

P0622 - Generator F field control circuit malfunction

What does trouble code P0622 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 Dodge, Jeep, Chevy, Ford, Land Rover, Toyota, Ram, etc. Despite the general nature, the exact repair steps may vary depending on the model year, make, model and configuration. transmissions.

A stored code P0622 means the powertrain control module (PCM) has detected a malfunction in the generator excitation coil control 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 PCM monitors the continuity and voltage level of the generator field control 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.

Each time the ignition is turned on and power is applied to the PCM, several controller self-tests are performed. In addition to performing a self-test on the internal controller, a Controller Area Network (CAN) is used to compare signals from each individual module to ensure that the various controllers are communicating as expected.

If a problem is detected while monitoring the alternator field control circuit, a P0622 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?

Internal control module codes should be considered serious. A stored P0622 code can result in a variety of handling problems, including not starting and / or low battery.

What are some symptoms of code P0622?

As we mentioned above, the Check Engine light should come on, but it may take more than one incident before it does. In this case, a vehicle scan may show that a P0622 code is pending. Other symptoms are more severe. The battery may be discharged, for example.Acceleration can get difficult. Fuel economy is likely to suffer as well.

While driving, you may find that shifting gears is a problem. The engine can also go deaf or even start to vibrate. If you put it at idle, the engine may make a strange noise.

How does a mechanic diagnose a P0622 code?

Symptoms of a P0622 trouble code may include:

• Engine control problems
• The engine stalls at idle speed
• Unintentional engine shutdown
• Engine start delay
• Problems with driving a vehicle, accompanied by problems with the operation of the engine.
• Car start delay.
• Presence of other OBDII error codes stemming from this underlying error.
• Constant burning of the Check Engine light on the dashboard.

What are some of the common causes of a code P0622?

Reasons for this code may include:

• Defective PCM
• PCM programming error
• Open or short circuit in the generator field control circuit
• Defective generator / generator
• The battery is fully charged.
• Poor electrical connection to the generator circuit.
• The generator is controlled directly by the engine control module.
• Faulty engine control module.

What are some steps to troubleshoot the P0622?

Diagnosing the P0622 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 P0622 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.

If the alternator is charging and the P0622 continues to reset, use the DVOM to test the fuses and relays on the controller power supply. Replace blown fuses if necessary. Fuses should be checked with a loaded circuit.

If all fuses and relays are working properly, a visual inspection of the wiring and harnesses associated with the controller should be performed. You will also want to check the chassis and motor ground connections. Use your vehicle information source to obtain grounding locations for associated circuits. Use DVOM to check ground integrity.

Visually inspect the system controllers for damage caused by water, heat, or collision. Any controller damaged, especially by water, is considered defective.

If the power and ground circuits of the controller are intact, suspect a faulty controller or a controller programming error. Replacing the controller will require reprogramming. In some cases, you can purchase reprogrammed controllers from the aftermarket. Other vehicles / controllers will require onboard reprogramming, which can only be done through a dealership or other qualified source.

• The excitation coil is an integral part of the generator and usually cannot be replaced separately.
• Check the ground integrity of the controller by connecting the negative test lead of the DVOM to ground and the positive test lead to the battery voltage.

Common Mistakes When Diagnosing Code P0622

Many underlying issues may play a role in maintaining this code. This is why the mechanic must take each code one at a time and fix them in that order using the freeze frame feature of their OBD-II scanner.

How serious is the P0622 code?

The problem is quite serious, given its impact on handling. This can seriously undermine the capabilities of the car. That being said, a CAN problem could mean that something broader is going on with the vehicle's electrical functions, which could represent a more serious problem.

What repairs can fix code P0622?

There are several things a mechanic can do to clean up this code:

• Replace all defective electrical components
• Disconnect all CAN pins and test each individually.
• Replace the control module ground wire.

However, there are a number of other paths the technician can take, depending on which module reported the issue and its status.

Additional comments to consider regarding code P0622

In addition to clearing trouble codes one at a time, the mechanic should also use resets to make sure their efforts actually fix the problem.

P0622 ✅ SYMPTOMS AND CORRECT SOLUTION ✅ - OBD2 Fault Code

Need more help with the P0622 code?

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