P0622 GENERATOR FIELD NOT SWITCHING PROPERLY

When Monitored and Set Condition:

When Monitored: When the ignition is on.
Set Condition: The feedback signal does not match the commanded signal for the voltage regulator.

POSSIBLE CAUSES

• GENERATOR
• OPEN DRIVER CIRCUIT
• GEN SOURCE SHORTED TO BATTERY NEGATIVE
• (K20) FIELD DRIVER CIRCUIT SHORTED TO VOLTAGE
• GEN SOURCE OPEN
• ECM

DIAGNOSTIC PROCEDURE

1. Turn the ignition off. Disconnect the Generator field harness connector. Check connectors - Clean/repair as necessary. Measure the resistance between the generator field terminals. Is the resistance between.5 and 15 Ohms?
   Yes --> Go To 2
   No --> Replace the Generator.
2. Disconnect the ECM harness connectors. Check connectors - Clean/repair as necessary. Measure the resistance of the generator driver wire between the generator harness connector and the ECM harness connector. Is the resistance less than 10 ohms.
   Yes --> Go To 3
   No --> Repair the open driver circuit.
3. Measure the resistance of the generator source circuit between the generator harness connector and battery negative. Is the resistance less than 10 ohms.
   Yes --> Repair the Gen source shorted to Battery negative.
   No --> Go To 4
4. Measure the voltage between the (K20) generator field driver circuit in the generator harness connector and battery negative. Is the voltage greater than 1 volt?
   Yes --> Repair the (K20) Generator field driver circuit shorted to voltage.
   No --> Go To 5
5. Measure voltage of the Gen source circuit at the generator harness connector. Is voltage within one volt of battery voltage?
   Yes --> Replace the ECM.
   No --> Repair the open or high resistance of Gen source circuit.