PIN 5T5965 - Caterpillar

Diagnostic codes alert the operator that a problem exists. Diagnostic codes indicate the nature of the problem to the service technician. Diagnostic codes consist of the MID, CID, and FMI. The module identifier (MID) indicates the electronic module that generated the diagnostic code. The MID for the ECM is 36. The component identifier (CID) indicates the component in the system. The failure mode identifier (FMI) indicates the failure mode that is present. Diagnostic codes may be viewed on an Electronic Service Tool. Do not confuse diagnostic codes with diagnostic events.
Active Diagnostic Codes
An Active diagnostic code represents a problem with the electronic control system. This problem should be corrected as soon as possible. When an active diagnostic code is generated, a display module such as the Electronic Monitoring System (EMS) may produce a warning.The ECM can generate the following actions when an active diagnostic code is present:
The ECM logs the code into permanent memory.
The ECM generates a diagnostic code on the CAT Data Link.
The ECM generates a Flash Code that will be displayed on the diagnostic lamp.
The warning lamp will be turned on.Possible Performance Effect of Active Diagnostic Codes
Table 1
Possible Performance Effect of Active Diagnostic Codes    
Flash Code    CID/FMI Code    Description of Code    Engine Misfires    Low Power    Reduced Engine Speed    Engine Shutdown    
N/A     545-05     Ether Start Relay open/short to +batt                    
545-06 Ether Start Relay short to ground                    
21     262-03     5 Volt Sensor DC Power Supply short to +batt                    
262-04 5 Volt Sensor DC Power Supply short to ground                    
263-03 Digital Sensor Supply short to +batt                    
263-04 Digital Sensor Supply short to ground                    
24     100-03     Engine Oil Pressure open/short to +batt                    
100-04 Engine Oil Pressure short to ground                    
25     273-00     Turbo Outlet Pressure above normal                    
273-03 Turbo Outlet Pressure open/short to +batt                    
273-04 Turbo Outlet Pressure short to ground                    
26     274-03     Atmospheric Pressure open/short to +batt                    
274-04 Atmospheric Pressure short to ground                    
27