MTG GP- 2976779 - Caterpillar

Monitoring System
The following is a list of codes that are associated with the active alarm circuit of the Monitoring System.
Table 1
Monitoring System Display (MID 053)    
DTC     Code Description     System Response    
271-5     Action Alarm: Current Below Normal     The alarm will not sound along with a visual alarm.    
271-6     Action Alarm: Current Above Normal     The alarm may sound constantly.    Note: The component identified in the troubleshooting table above is connected to the Monitoring System. The Monitoring System activates the alarms after receiving a signal from the J1939 Data Link. If a CID 247 is active, the troubleshooting for the J1939 Data Link must be performed before proceeding.Possible causes for an FMI 5 diagnostic code are:
The energize circuit of the action alarm is open.
The return circuit of the action alarm is open.
The action alarm has failed.
The Monitoring System has failed. A failure of the Monitoring System is unlikely.Possible causes for an FMI 6 diagnostic code are:
The action alarm circuit is shorted to ground
The action alarm has failed.
The Monitoring System has failed. A failure of the Monitoring System is unlikely.
Illustration 1 g03677785
Note: The diagram above is a simplified schematic of the "Action Alarm" and "Action Alarm" connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, KENR7524 for the complete schematic.Diagnostic Trouble Code Procedure
Note: Prior to beginning this procedure, inspect the harness connectors that are involved in this 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 the diagnostic code is active before performing a troubleshooting procedure.
Table 2
Troubleshooting Test Steps    Values    Results    
1. Identify The Active FMI Code Associated With The Circuit    
Code present.    
FMI 5 diagnostic code, proceed to Test Step 2.
FMI 6 diagnostic code, proceed to Test Step 4.    
Begin Procedure For FMI 5 Troubleshooting HERE    
2. Check The Alarm
A. Turn the key start switch and disconnect switch ON. Do NOT start the engine.
B. Disconnect alarm from machine harness.
C. At harness connector for the alarm, place a jumper wire between connector 1 and connector 2.
D. Observe status of diagnostic code.    
Code for alarm circuit remains active.     OK - Diagnostic code remains active, jumper wire does not affect diagnostic code.
Proceed to Test Step 3.
NOT OK - Diagnostic code changes from FMI 5 to FMI 6.
Repair: Replace the alarm. Verify that the new alarm corrects the problem.
STOP.    
3. Check The Harness For An Open
A. Turn the key start switch and disconnect switch OFF.
B. Disconnect harness connectors from the Monitoring System Display.
C. The jumper wire from the previous test remains installed.
D. At the Monitoring System Display connector, measure the resistance from signal contact to ground contact.    
The reading is less than 5 Ω.     OK