Design and function Engine speed Coolant temperature Accelerator linkage Charge air temperature Charge air pressure Control rod position Regulator selector Fuel temperature EDC system control unit Monitoring functions The control unit, which is built into the fuel filters, re- ceives signals from the following sensors (sensor loca- tion is noted in brackets). The EDC system contains functions for monitoring the following parameters on the engine:
Control rod position (injection pump) Engine speed (injection pump) Control rod position Engine speed EDC fault codes Charge air pressure (control unit) Charge air pressure Charge air temperature (inlet manifold) Charge air temperature Coolant temperature (thermostat housing) Coolant temperature Fuel temperature (control unit) Fuel temperature Accelerator position (driver’s foot pedal) Using these signals, the control unit directs the injec- tion pump to provide the engine with the correct amount of fuel under every loading.
Excess current, (control unit) if the above-mentioned sensors give unreasonable val- ues, the system takes various measures to protect the engine and its auxiliaries (e.g. the turbocharger). If anything abnormal occurs, the control unit generates and stores a code. The diagnosis lamp on the EDC control panel then begins to flash. The number of flashes given by the diagnosis lamp corresponds to the relevant fault code, which is ob- tained by pressing the diagnosis button.
To protect the engine if there is excessive charge tem- perature, coolant temperature, charge air pressure, en- gine speed, the EDC system reduces the amount of fuel injected (and thus reduces power) until the relevant values return to the permissible interval. The engine must be re-started to get normal power back. Please refer to the “Function checking with diagnosis button“ chapter for function checking with the diagnosis button, and fault codes. In addition, there are Limp-home values (emergency control parameters) stored in the control unit. These come into action if there are any technical faults in the system or its auxiliaries, sensors etc.
Limp-home val- ues are activated to allow the engine to continue in op- eration, but at reduced performance. The control unit also contains a diagnosis function, which can help the user/service personnel to quickly find any faults in the system, by using a diagnosis lamp, diagnosis instrument or PC based diagnosis pro- gram.
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