The Caterpillar Electronic Technician (ET) can select the ECM response. The Cat ET can be used to program the level of engine monitoring and the delay times.
ECM Supply Voltage
The ECM will provide a warning for low system voltage. The voltage must be below the trip point of 20 volts for 10 seconds in order for an alarm to occur. Once the alarm becomes active, the voltage must be above 22 volts in order to deactivate the alarm.
Engine Overspeed
The ECM will provide an alarm for engine overspeed. The ECM will provide an engine shutdown if there is an engine overspeed. The ECM will provide an alarm when the engine speed exceeds 1962 rpm. The ECM will provide an engine shutdown if the engine speed is above 2070 rpm. The ECM must be reset after an occurrence of overspeed shutdown.
Crankcase Pressure
High Crankcase Pressure
The ECM will not provide an alarm for high crankcase pressure. The ECM will not provide an engine shutdown for high crankcase pressure.
Low Crankcase Pressure
The ECM will provide an alarm for crankcase pressure when crankcase pressure is 2 kPa (0.29 psi) for 3 seconds. The ECM will provide an engine shutdown when crankcase pressure is 3.5 kPa (0.51 psi) for 3 seconds.
Engine Oil Pressure
The ECM provides an alarm in the event of low engine oil pressure. The ECM provides an engine shutdown in the event of low engine oil pressure. The strategy for low engine oil pressure is based on an oil pressure map. The strategy for low engine oil pressure is not based on specific setpoint information. Refer to Illustration 1.
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| Illustration 1 | g00924934 |
Separate timers are used in the ECM for each response that is associated with a parameter. Once the trip point is exceeded for an action, the timer for that action is started. For example, if the ECM supply voltage is set to 20 volts with a 10 seconds delay, the delay timer starts counting once the voltage falls below 20 volts. If the voltage falls below 20 volts for 10 seconds, a warning would be issued.
The engine monitoring system is enabled after the engine is started. When the engine is within 50 rpm of low idle, the ECM will check the parameters. The ECM will not check the parameter for low oil pressure. Low oil pressure has an additional 10 second delay after the engine is started. The delay is designed to eliminate false low oil pressure warnings.
Use care when you program the trip point and the delay times. The resulting ECM response must be correct for the application. If the legal range is not exceeded, the engine monitoring system will accept any setting.
If the trip point for a shutdown is lower than the trip point for a warning, the engine will shut down. The warning will not be activated.
Once a parameter has exceeded the trip point the parameter must drop below the trip point or go above the trip point before the ECM response will end.
If a warning for ECM supply voltage is programmed to 20 volts, the voltage must fall below 20 volts in order for the warning to activate. The voltage must rise above 22 volts for the warning to stop. The variance is the hysteresis.