REGULATOR ASSEM. 7N0178 - Caterpillar

Illustration 1 g06016284
Simplified Schematic for CID 1674 (Solenoid Return #1)
This diagnostic code is associated with the "Solenoid Return #1" circuit. The FMI 03 means that the Brake ECM has determined that the voltage in the return circuit for the Automatic Retarder Control (ARC) solenoids is above normal. This condition is likely caused by a short to another voltage source.For more information on the ARC solenoids, refer to Systems Operation, "Electrical Output Components" in this manual.Conditions that could cause this diagnostic code to be activated are listed below:
The return circuit of an ARC solenoid is shorted to another voltage source.
The ECM has failed. ECM failure is unlikely.Note: Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure and in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear these diagnostic codes when the original diagnostic code has been corrected.Test Step 1. CHECK THE RETURN CIRCUIT OF THE SOLENOIDS FOR A SHORT
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connectors from both of the secondary steering solenoids. Disconnect the J1 machine harness connector from the Brake ECM.
At the machine harness connectors for the Brake ECM, measure the resistance from the return contact of the solenoid, J1-54 (wire J815-BK(Black)) and the following contacts:
J1-67 (wire K988-WH(White))
J1-68 (wire F792-WH(White))Expected Result:Each resistance measurement is greater than 5000 ohms.Results:
YES - Each resistance measurement is greater than 5000 ohms. The resistance measurement does not indicate a short in the machine harness. Proceed to Test Step 2.
NO - Each resistance measurement is not greater than 5000 ohms. There is a short in the machine harness.Repair: The short is between wire P997-BR(Brown)and the circuit that has a low-resistance measurement.
For information on testing for short circuits and finding short circuits, refer to Testing and Adjusting, "Wiring Harness (Short Circuit) - Test" in this manual.
Repair or replace the machine harness.STOPTest Step 2. CHECK THE OPERATION OF THE ECMThe disconnect switch and the key start switch remain in the OFF position. The machine harness connectors for the solenoids and the ECM remain disconnected.
At the machine harness connector J1 for the ECM, use a 151-6320 Removal Tool to remove the return wire P997-BR(Brown)and the socket at contact J1-54 from the harness connector.
Reconnect the J1 machine harness and connectors to the ECM.
Turn the disconnect switch and the key start switch to the ON position.
Observe the status of the active CID 1674 FMI 03 diagnostic code.Expected Result:The CID 1674 FMI 03 diagnostic code is no longer active. A CID 1674 FMI 05 diagnostic code is now active.Results:
YES - The CID 1674 FMI 03 diagnostic code is no longer active. A CID 1674 FMI 05 diagnostic code