CYLINDER HEAD AS 7N8524 - 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 ignition key to the ON position. The engine does not need to be started in order to view any codes.The "DIAGNOSTIC" lamp blinks on and off at five second intervals.When the ignition key is in the ON position, the lamp is checked for proper operation. Any active codes are displayed.Note: The "DIAGNOSTIC" lamp will illuminate for five seconds. The lamp will stay on if there is an active diagnostic code.
The diagnostic codes will always be flashed. There is no toggle switch that will shut off the lamp.
The "DIAGNOSTIC" lamp will flash in order to indicate a two-digit code. The sequence of flashes represents the system diagnostic message. Each digit of the two-digit code is determined by counting the number of flashes. The lamp flashes at a rate of two times per second. The lamp will pause for one second between digits. The lamp will pause for two seconds between codes.Table 1 indicates the potential effect on the engine performance with active flash codes.
Table 1
   Diagnostic Flash Code and Relationship of Engine Performance in a 3408 Marine Engine and a 3412 Marine Engine    
Diagnostic Flash Code    Effect On Engine Performance    Suggested Operator's Steps    
Engine Misfire Low Power    Reduced Engine Speed    Shut down the Engine (1)    Service (2)    Scheduled service (3)    
21     Sensor Supply Voltage Above/Below Normal (4)         X                 X    
22     Sensor Fault for Fuel Rack Position         X                 X    
24     Oil Pressure Sensor Open/Short Normal (4)                         X    
25     Inlet Air Manifold Pressure Sensor Open/Short (5)         X                 X    
27     Coolant Temperature Sensor Open/Short (4)                         X    
28     Check Throttle Sensor Adjustments                         X    
32     Throttle Position Sensor Fault, Inlet Air Manifold Pressure Sensor Calibration             X         X        
33     Engine Speed Fault                            
34     Loss Of Engine RPM Signal     X         X         X        
35     Engine Overspeed Warning                         X    
42     Check Timing Sensor Calibration         X                 X    
43     Rack Subsystem Fault                            
45     Shutoff