P0622 - GENERATOR FIELD CONTROL CIRCUIT F MALFUNCTION

When the error code P0622 OBDII is stored it means that the Power Train Control Module (PCM) has observed a malfunction in the generator field coil control circuit. The letter F indicates that the field coil control circuit is defective.

The field coil is around the generator armature and remains in the alternator housing. The PCM constantly checks the continuity and also voltage level of the generator field control circuit whenever the engine is in action. The generator field coil is a fundamental part of the correct operation of the generator and also maintains the battery charge levels.

Each time the vehicle is turned on and the PCM is activated, multiple driver self-tests are performed. Also, through the Control Area Network (CAN) the internal controller is self-tested to compare the signals from each module. If a problem is found in the generator field control circuit, the DTC code P0622 OBD2 is set and the Check Engine light is illuminated.

• Warning light (MIL) on.
• The vehicle may show signs that the battery is discharged.
• When driving the functions are limited due to battery discharge.
• At idle the engine can be turned off.

The storage of fault code P0622 OBDII is due to the following:

• There may be burned, short, or badly connected connectors.
• The control circuit of the generator field in short.
• The alternator may be defective.
• PCM programming error.

The steps to solve the failures related to the diagnostic code P0622 OBD2 are

• Check for Technical Service Bulletins (TSB). The solution to the problem may be known by the manufacturer.
• Check that the battery is fully charged. If not, charge it to the required level and test the alternator. Consult the manufacturer's specifications for minimum and maximum voltage output requirements for the battery and alternator. If they do not match, it is because the alternator is not charging correctly.
• With the help of the wiring diagram and a DVOM (Digital Volt-Ohm Meter), check if the battery voltage is present in the alternator field control circuit. If not, check the state of the system fuses and relays and change them if they are defective. Fuse tests should be performed with the circuit loaded. If the control terminal of the coil has voltage, the alternator is in bad condition.
• Perform an inspection of the wiring related to the controller. Also, check the ground connection between the chassis and the engine. Use the meter to check for good ground.
• Check the controller for the presence of water, heat, or physical shocks. If water is present, the controller may be defective, replace it.
• Change the driver. The change requires reprogramming.