ADAPTER- 9U5338 - Caterpillar

Diagnostic Codes
Diagnostic codes are used by the electronic system to alert the operator that a problem exists and indicates to the service technician the nature of the problem.The CID, or Component IDentifier, tells which component in the system the diagnostic code is for. The FMI, or Failure Mode Identifier indicates what the failure mode is.Diagnostic Codes may be viewed using Electronic Service Tools. To troubleshoot a Diagnostic Code, refer to the reference table in this section under the specific code number. The code number will direct you to a procedure in Section 5: Functional Tests. Do not confuse diagnostic codes (Active or Logged) with diagnostic events! Events can be logged in the ECM to track operating information about the engine conditions. An example would be a low fuel pressure event. A logged event code is generated when the engine fuel pressure is low, but not out of range for the sensor to communicate with the ECM, which would generate a diagnostic code. This occurrence does not indicate a problem with the engine sensor, rather it would be an indication there is a problem with engine fuel pressure.Active Diagnostic Codes
An ACTIVE diagnostic code represents a problem with the electronic control system that should be investigated and corrected as soon as it is practical.When an ACTIVE diagnostic code is generated, a display module such as the Electronic Monitoring may indicate the diagnostic code. If the condition generating the diagnostic occurs only for a brief moment, the message will disappear and the diagnostic code will be LOGGED in the ECM memory.Logged Diagnostic Codes
When the ECM generates a diagnostic code, it usually logs the code in permanent memory within the ECM. The ECM has an internal diagnostic clock and will record the hour of the first occurrence, the hour of the last occurrence and the number of occurrences of the code. Knowing when and how often the code was generated can be a valuable indicator when troubleshooting intermittent problems. The ECAP Electronic Service Tool can be used but does not support all logged codes.Logged codes can be retrieved or erased using an Electronic Service Tool. Logged diagnostic codes will automatically be deleted if no additional occurrences are recorded in 100 hours.When investigating logged diagnostic codes, keep in mind the following information.* Some diagnostic codes may be sensitive, and may log occurrences that did not result in operator or pilot complaints. If the time the code was logged does not correlate to a complaint, there may be nothing to fix.* The most likely cause of an intermittent problem is a faulty connection or damaged wiring. Next likely is a component failure (sensor or switch). Least likely is failure of the ECM itself.* Diagnostic codes that are logged repeatedly may indicate a problem that needs special investigation.To troubleshoot a logged diagnostic code, refer to the Diagnostic Code Cross Reference to Functional Test Procedures in this section under the specific code number. The code number will direct you to a procedure in Section 5: