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DTC P0622: Generator Field Not Switching Properly: Testing

  1. Ignition on, engine not running. Record all DTCs and the related Freeze Frame data. Using a 12-volt test light connected to ground, backprobe the (K20) Generator Field Control circuit at the back of the Generator. With the DRBIII®, actuate the Generator Field Driver. Does the test light blink? If yes, go to next step. If no, go to INTERMITTENT CONDITION  under SELF-DIAGNOSTIC SYSTEM.
  2. Backprobe the (K125) Generator Field Source circuit at back of Generator with a volt meter. With the DRBIII® actuate the Generator Field Driver. Is the voltage above 10.0 volts? If yes, go to the next step. If no, repair the open in the (K125) Generator Field Source circuit.
  3. Turn the ignition off. Disconnect the PCM harness connectors. Disconnect the Generator Field harness connector. Measure the resistance of the (K20) Generator Field Control circuit from the Generator Field harness connector to the PCM harness connector. Is the resistance below 5.0 ohms? If yes, go to the next step. If no, repair the open in the (K20) Generator Field Control circuit.
  4. Measure the resistance between ground and the (K20) Generator Field Control circuit in the PCM harness connector. Is the resistance below 100 ohms? If yes, repair the short to ground in the (K20) Generator Field Control circuit. If no, go to the next step.
  5. Measure resistance across the Generator Field Terminals at the Generator. Is the resistance between 0.5 and 15 ohms? If yes, go to next step. If no, repair the Generator as necessary.
    6. NOTE: Before continuing, check the PCM harness connectors for corrosion, damage, or terminal push out. Repair as necessary.
  6. Using the wiring diagram as a guide, inspect the wire harness and connectors. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace PCM. Program the new PCM. See PROGRAMMING .
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