CUP 1730594 - Caterpillar

Use this procedure in order to troubleshoot an engine overspeed or use this procedure if one of the following event codes is active. Refer to Troubleshooting, "Event Code List" for information about event codes and the default trip points for these codes. You must access the monitoring system on Caterpillar Electronic Technician (ET) in order to view the current trip points for these codes.
Table 1
Event Code    
Code and Description    Conditions which Generate this Code    System Response    
E004(3) Engine Overspeed Shutdown     The engine rpm has exceeded the trip point for engine overspeed for the delay time.     The air shutoff will be activated. The engine will shut down.
Power must be cycled to the engine's Electronic Control Module (ECM) in order to reset the code.
The code is logged.    
E190(1) Engine Overspeed Warning     The code is logged. Probable Causes
Intake air is combustible.
Sudden drop of load
The Overspeed Verify Switch is activated.Recommended Actions
Intake Air is Combustible
Check for hydrocarbons in the surrounding atmosphere. Do not operate the engine in an environment with hydrocarbons in the surrounding atmosphere.Sudden Drop of Load
Decrease the load on the engine gradually.Check the Overspeed Verify Switch
The Overspeed Verify Switch provides a way to check the system at 75 percent of the set point. The set point is 118 percent over the rated engine rpm. When the engine reaches the set point, the strategy for the overspeed is initiated. This action will test the shutoff system. The Overspeed Verify Switch allows you to verify proper operation of the system. If the "Engine Overspeed Shutdown" code or the "Engine Overspeed Warning" code is logged before reaching full engine rpm, the Overspeed Verify Switch should be checked for proper operation. Refer to Troubleshooting, "Overspeed Verify Switch " for troubleshooting information.