CHASSIS AS 2454657 - Caterpillar

Oil Pressure Map
Illustration 1 g00911985
Oil pressure mapSeparate 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 high Coolant Temperature Warning is set to 102 °C (216 °F) with a five seconds delay, the delay timer starts counting once the coolant temperature exceeds 102 °C (216 °F). If the coolant remained above 102 °C (216 °F) for five 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 a certain amount below the trip point before the ECM response will end.If a warning is programmed to 102 °C (216 °F) the temperature must exceed the range in order for the warning to activate. The temperature must decrease below 99 °C (210 °F) for the warning to stop. The variance is the hysteresis. The following table gives the hysteresis for each parameter.
Table 2
Parameter     Hysteresis    
ECM Voltage     3 VDC    
Oil Pressure    
20 kPa (3 psi)    
High Coolant Temperature     3 °C or 6 °F    
Low Coolant Temperature     3 °C or 6 °F    
Overspeed     100 rpm    
Air Inlet Restriction     N/A    
Altitude     N/A    
High Exhaust Temperature    
102 °C (216 °F)    
Oil Filter Differential Pressure    
10 kPa (1.5 psi)    
Fuel Filter Differential Pressure    
10 kPa (1.5 psi)    
Crankcase Pressure     N/A    
Aftercooler Water Temperature     3 °C or 6 °F    Most active engine derates that occur are activated when the associated parameter is out of range.When the parameter returns to normal operation, the active engine derate is disengaged.There are a few exceptions:
High exhaust temperature
High air filter restriction
Crankcase pressureThe active engine derate is latched until the ECM is powered down.