MOUNT AS 4W0077 - Caterpillar

Using Cat® Electronic Technician (Cat® ET) to Determine Diagnostic Codes
Perform the following:
Connect Cat® Electronic Technician (Cat® ET) 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 (ECM modules) on the machine will be established.Cat® ET will list the ECM modules.
Choose the desired ECM.Cat® ET will display the diagnostic codes.
See the test procedure, within this service manual, corresponding to the active, or logged diagnostic code.Reference: Troubleshooting, "Service Tools"Diagnostics are logged in non-volatile memory.Active Diagnostic Codes
Illustration 1 g02625416
Typical Cat® Electronic Technician (Cat® ET) Service Tool screen for 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 displayed in Cat ET.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:
Component identifier (CID) or Suspect Parameter Number (SPN).
Failure mode identifier (FMI).
Text description of the problem.Logged Diagnostic Codes
Illustration 2 g02625437
Typical Cat® ET screen for logged diagnostic codes
Cat® ET displays logged diagnostic codes. Intermittent problems are shown as logged diagnostic codes. The logged diagnostic data includes the following:
Component identifier (CID) or Suspect Parameter Number (SPN).
Failure mode identifier (FMI).
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.