TUBE AS 3157332 - Caterpillar

Illustration 1 g02594859
Schematic of the Parking Brake Pressure SwitchThis diagnostic code is associated with the Parking Brake Pressure Switch. The switch is connected to two inputs of the ECM. The inputs are "Normally Open" and "Normally Closed". One of the inputs is open and the other input is grounded during proper operation.
Table 1
Status of Parking Brake Pressure Switch    
Parking Brake Pressure Switch    Terminal B
(N/O)
Wire G756-YL
J2-53    Terminal C
(N/C)
C491-PU
J2-52    
Low Pressure
Parking Brake Engaged     Open     Closed    
High Pressure
Parking Brake Engaged     Closed     Open    The FMI 04 means that the ECM has determined that the "Normally Open" and "Normally Closed" circuits are grounded.Note: The following test procedure may create other diagnostic codes. Ignore these diagnostic codes and clear these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 0627 FMI 04 is active before performing this procedure.System Response:The Parking Brake Lockout is disabled.Test Step 1. CHECK THE SWITCH
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness from the switch.
Turn the key start switch and the disconnect switch to the ON position.Expected Result:The CID 0627 FMI 04 has been replaced by CID 0627 FMI 03.Results:
OK - The CID 0627 FMI 04 has been replaced by CID 0627 FMI 03. The machine harness and the ECM are correct. Proceed to Test Step 3.
NOT OK - The CID 0627 FMI 04 is still active. Proceed to Test Step 2.Test Step 2. CHECK THE HARNESS
Turn the disconnect switch and the key start switch to the OFF position.
The machine harness remains disconnected from the switch.
Disconnect the machine harness connectors from the ECM.
Measure the resistance between contacts J2-53 (wire G756-YL) and J2-52 (wire C491-PU) of the machine harness to all the contacts that are used in machine harness connectors for the ECM.Expected Result:Each resistance measurement is greater than 5000 ohms.Results:
YES - Each resistance measurement is greater than 5000 ohms. The ECM has failed.Repair: Failure of the ECM is unlikely. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, contact your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. Refer to the Testing and Adjusting, "Electronic Control Module (ECM) - Replace" Section of this manual for additional details.STOP
NO - One or more of the resistance measurements are less than 5 ohms. The harness has failed. The short is between J2-53 (wire G756-YL) and the circuit with the lowest resistance or the short is between J2-52 (wire C491-PU) and the circuit with the lowest resistance. Repair: Repair the wiring harness or replace the wiring harness.STOPTest Step 3. CHECK THE OPERATION OF THE SWITCH
The machine harness remains disconnected from the switch.
Connect one lead from a multimeter to contactA (wire A273-BK) of the harness connector for the switch.
Connect the other lead from a multimeter to contact B (wire G756-YL) of the harness connector for the switch.
Measure the resistance between contact A