Component description Function check with diagnosis instrument Sensor, coolant, charge air, fuel temperature and charge air pressure General information When the control unit receives system voltage, the control unit checks the system. There is a service/diag- nostic instrument for the EDC system, to read the re- sults of checks for diagnosis and function checking. The instrument makes it easier to quickly localise and fix any faults in the EDC system. Coolant temperature sensor (12) The sensor, which is located in the thermostat housing, gives the control unit information about engine coolant temperature.
This consists of a non-linear resistor, whose resistance is highly dependent on the tempera- ture of the resistor body. The resistance falls as the temperature rises. Diagnosis instrument Charge air temperature sensor (20) The instrument has a window (1) where menus for dis- playing fault codes, sensor values and input/output sig- nals are displayed. The menus can be supplemented and modified, such as other languages in the menus, by just changing the cassette (5) which contains the in- strument software. The sensor is located underneath the intercooler on the right side of the engine.
This consists of a non-linear re- sistor, whose resistance is highly dependent on the temperature of the resistor body. The resistance falls as the temperature rises. There are three buttons under the instrument display, two arrows (2) and (3) and an Execute button (4) which corresponds to “Enter“ on a computer. Fuel temperature sensor (21) The sensor is located inside the fixing lug on the con- trol unit for the fine fuel filter. Service/diagnostic instrument The fuel flows from the filter head, via the fixing lug and on through the filter, back into the system. When the fuel passes the fixing lug, the sensor provides in- formation about current fuel temperature to the control unit.
The fuel also cools the control unit to a certain ex- tent. 1. Display 4. Execute button (“Enter” on a com- 2. Arrow key, left puter) 3. Arrow key, right 5. Program cassette (change to change language) The sensor consists of a non-linear resistor, whose re- sistance is highly dependent on the temperature of the resistor body. The resistance falls as the temperature rises. Since the sensor is integrated into the control unit, it can not be replaced separately, the entire control unit must be changed if necessary. Instruments Connection The instrument is connected to a connector on the in- strument panel.
Charge air pressure sensor (22) The sensor, which is integrated into the control unit, senses the charge air pressure via an air pressure pipe, which is connected between the inlet manifold and the T-nipple underneath the control unit. The sensor measures absolute pressure, which is the sum of charge pressure plus atmospheric pressure. The installer is responsible for ensuring that this con- nector is wired in. Connect the red and black clamps on the diagnostic instrument cables to the positive (+) and negative (-) terminals on the engine electrical system, or another power supply (24 V).
Connection of diagnostic instrument Since the sensor is integrated into the control unit, it can not be replaced separately, the entire control unit must be changed if necessary. 32 21