ENGINE AR 4W9127 - Caterpillar

Using Cat® Electronic Technician (Cat ET) Service Tool to Determine Diagnostic Codes
Perform the following:
Connect Cat® Electronic Technician (Cat ET) Service Tool to the machine.
Turn the key start switch to the RUN position.
Start Cat ET. After Cat ET is started, communications with the electronic control modules (ECMs) on the machine will be established.Cat ET will list the ECMs.
Choose the desired ECM. Cat ET will determine the diagnostic codes.
See the test procedure for the corresponding diagnostic code. Reference: Troubleshooting, "Service Tools"Diagnostics are logged in non-volatile memory. On powerup, the ECM will clear any diagnostic codes that have not been detected or active within the last 150 hours of machine operation.Active Diagnostic Codes
The following procedures may cause new diagnostic codes to be logged. Before any procedures are performed, make a list of all the active diagnostic codes. When each procedure is complete, clear the diagnostic codes that were caused by the procedure.Note: Before performing a procedure, always check all the circuit breakers. Repair the cause of any tripped circuit breaker.Cat ET displays active diagnostic codes. Active diagnostic data includes:
CID (Component Identifier)
FMI (Failure Mode Identifier)
Text description of the problemLogged Diagnostic Codes
Cat ET displays logged diagnostic codes. Intermittent problems are shown as logged diagnostic codes. The logged diagnostic data includes the following:
CID (Component Identifier)
FMI (Failure Mode Identifier)
Text description of the problem
Number of occurrences of the problem
Time stamp of the first occurrence of the problem
Time stamp of the most recent occurrence of the problem