KIT-SEAL 2159986 - Caterpillar

"Diagnostic" Lamp
Use the "DIAGNOSTIC" Lamp or a Caterpillar electronic service tool to determine the diagnostic flash code.Use the following procedure to retrieve the diagnostic codes if the engine is equipped with a "DIAGNOSTIC" lamp:
Turn the cruise control ON/OFF switch to the OFF position.
Move the SET/RESUME switch to either position. Hold that position until the "YELLOW" lamp begins to flash.The "YELLOW" lamp will flash in order to indicate a two digit flash code and the SET/RESUME switch may be released. The sequence of flashes represents the system diagnostic message. Count the first sequence of flashes in order to determine the first digit of the diagnostic code. After a two second pause, the second sequence of flashes will identify the second digit of the diagnostic code.Any additional diagnostic codes will follow after a pause. The additional diagnostic codes will be displayed in the same manner. Flash Code 55 signals that No Detected Faults have occurred since the ignition keyswitch has been turned to the ON position.Refer to the Service Manual or consult an authorized Caterpillar dealer for the following items.
Further information
Assistance for repairs
TroubleshootingThe electronic diagnostic codes are listed and described in Table 1.Note: Table 1 indicates the potential effect on engine performance with "ACTIVE" flash codes.Some codes record events or some codes indicate that a mechanical system needs attention rather than indicating a performance problem. Troubleshooting is not required for codes "35", "41", "47" and "55". Code "01" will not flash. Some codes will limit the operation or the performance of the engine.Table 1 indicates the potential effect on the engine performance with active flash codes. Table 1 also forms a list of Electronic diagnostic codes and descriptions.
Table 1
Diagnostic Flash Code or Engine Performance Relationship    
Diagnostic Flash Code    Effect On Engine Performance (1)    Suggested Action of the Operator    
Misfire Low Power Loss of RPM    Shut Down    Stop
Engine (1)    Service
Engine (2)    Schedule
Engine
Service (3)    
01     Idle Shutdown Override                                
12     Coolant Level Sensor Fault (5)                             X    
13     Fuel Temperature Sensor Fault                             X    
14     Retarder Solenoid Fault                             X    
21     Sensor Supply Voltage Fault (5)