SEAL --TO PILOT RING 4L4355 - Caterpillar

The EFR will immediately disable regulator operation.The possible condition that can cause the Drivetrain ECM to activate this diagnostic code are listed:
There is a short circuit to a ground source in the enable circuit between the ECM and the EFR.
The EFR has failed.
The ECM has failed.During machine operation, the Excitation Field Regulator (EFR) supplies 144.0 DC volts to the Generator exciter windings through current drive circuits. These circuits are connected in the four contact exciter circuit harness connectors at the EFR and at the Generator auxiliary enclosure. After machine shutdown, these circuits can contain hazardous voltage levels for approximately 5 minutes. After Engine shutdown, wait for at least 5 minutes before disconnecting the four contact exciter circuit connectors at the EFR and at the enclosure or before entering the Generator auxiliary enclosure. Always use a multimeter to verify that there is 50.0 VDC or less at any exposed exciter circuit contacts before any other action is taken.Points to consider before performing this procedure:
During normal operation with the key start switch is in the ON position (Engine OFF), the EFR feedback PWM duty cycle is expected to be 10 percent. When the Engine is operating, the PWM duty cycle is expected to be 50 percent.
On the right-hand side of the cab, the EFR control circuits pass through the cab wall in the round 24 contact MC-C3 / EF-C1 connectors that are shown in the diagram at the beginning of this procedure. When this connector is disconnected, this connection provides a good check point in order to determine if there is a short circuit, an open circuit, or a poor connection in the cab sections of the harness or in the chassis sections of the harness. Test Step 1. CHECK THE ENABLE CIRCUIT FOR A SHORT TO GROUND
Turn the key start switch and the battery disconnect switch to the OFF position.
At the EFR, disconnect the 14 contact control circuit harness connector from the module connector. Visually inspect each of the connector contacts for damage or contamination. Verify that the contacts are clean, secured, in the connector and in good condition.
At the mating connector on the EFR, measure the resistance between the enable circuit contact J and a good frame ground point.
At the Drivetrain ECM, disconnect the J1 and the J2 harness connectors. Visually inspect each of the connector contacts for damage or contamination. Verify that the contacts are clean, secured, in the connector and in good condition.
At the J2 machine harness connector for the Drivetrain ECM, measure the resistance between the enable circuit contact J1-12 (wire E865) and a good frame ground point.Expected Result:The resistance measurement between contact J and frame ground is greater than 4000 ohms. The resistance check between the harness enable circuit at the Drivetrain ECM connectors is greater than 4000 ohms.Results:
OK - The enable circuit resistance checks to frame ground do not indicate a short circuit to ground in the machine harness or in the EFR. Proceed to Test Step 2.
NOT OK - One or both