Caterpillar provides a factory installed Engine Monitoring system. The Caterpillar Engine Monitoring system monitors engine coolant temperature. The coolant temperature sensor is standard on all engines.
Caterpillar Engine Monitoring can be programmed to three different modes (OFF, WARNING, or DERATE) through a Customer Parameter. The Coolant Temperature Sensor will operate in the Engine Monitoring Mode selected.
NOTE: Excessive Coolant Temperature will not shut down the engine.
Caterpillar Engine Monitoring OFF Operation
If Caterpillar Engine Monitoring is programmed to OFF, the control system ignores the coolant temperature sensor if conditions are exceeded which could cause the ECM to take Engine Monitoring action.
The engine still uses the Coolant Temperature sensor for normal engine operation, such as for Cold Mode operation.
Caterpillar Engine Monitoring WARNING Operation
If the system is programmed to WARNING, the ECM causes the Check Engine Lamp to Flash (because of the Active Diagnostic Code) to indicate a problem has been detected by the Engine Monitoring System. The diagnostic code is logged. No further ECM or engine action occurs if the ECM is programmed to WARNING.
Caterpillar Engine Monitoring DERATE Operation
Figure 1 – Engine Monitoring Coolant Temperature Graph
Figure 2 – Engine Monitoring Coolant Temperature Graph
Figure 3 – Engine Monitoring Coolant Temperature Graph
If the system is programmed to DERATE, the ECM begins by flashing the Check Engine Lamp to indicate a problem has been detected by the Engine Monitoring System. The diagnostic code is logged. The ECM limits the maximum vehicle speed and reduces available power as shown below.
This derating of usual engine performance is provided to influence the drivers’ attention so action can be taken to avoid engine damage. The three graphs above show the temperature derate trip points for the 3100 engines, and a rating for special applications.