P0622-GENERATOR FIELD CONTROL CIRCUIT





For a complete wiring diagram Refer to Section 8W.



Possible Causes
(K125) GEN FIELD CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGE
(K125) GEN FIELD CONTROL CIRCUIT OPEN
(K125) GEN FIELD CONTROL CIRCUIT SHORTED TO GROUND
GENERATOR
PCM


Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).



Diagnostic Test

1. ACTIVE DTC

Ignition on, engine not running.
With a scan tool, select View DTCs.

Is the DTC Active at this time?

Yes


No

2. GENERATOR OPERATION



Turn the ignition off.
Disconnect the Generator Field harness connector.
Using a 12-volt test light connected to ground, probe the (K125) Generator Field Control circuit in the Generator Field harness connector.
Ignition on, engine not running.

NOTE: The DTC needs to be cleared before actuating the Generator Field, if the DTC is not cleared, the Generator Field may not be allowed to actuate.


With the scan tool, actuate the Generator Field Control circuit.

Does the test light illuminate brightly and flash on and off?

Yes


No

3. (K125) GEN FIELD CIRCUIT SHORTED BATTERY VOLTAGE



Turn the ignition off.
Disconnect the C2 PCM harness connector.
Ignition on, engine not running.
Measure the voltage on the (K125) Gen Field Control circuit in the Generator Field harness connector.

Is the voltage above 0 volts?

Yes


No

4. (K125) GEN FIELD CIRCUIT OPEN



Turn the ignition off.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.


Measure the resistance of the (K125) Gen Field Control circuit from the Generator Field harness connector to appropriate terminal of the special tool #8815.

Is the resistance below 5.0 ohms?

Yes


No

5. (K125) GEN FIELD CIRCUIT SHORTED TO GROUND



Measure the resistance between ground and the (K125) Gen Field Control circuit in the Generator Field harness connector.

Is the resistance below 100 ohms?

Yes


No

6. PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.


Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Were there any problems found?

Yes


No