Shown on engine 642.896, view of engine from above |
70 | Fuel filter |
R53/4 | Fuel filter heater with condensation sensor (engine 642.896) |
N47.50-2005-12
Location
The fuel filter heater with condensation sensor (engine 642.896) or the fuel filter water level sensor (B76) (engine 642.992) is inserted from above into the fuel filter.
Task
The condensation sensor for the fuel filter heater with condensation sensor (engine 642.8) or the fuel filter water level sensor (engine 642.9) detects the condensation level in the fuel filter.
The measurement is made using an AC voltage in order to avoid corrosion of the electrodes through electrolysis.
Engine 642.896 |
70 | Fuel filter |
76/1 | Electrode 1 |
76/2 | Electrode 2 |
76/3 | Integrated electronics |
76/4 | Plug (to water suction) |
76/5 | Heating element |
R53/4 | Fuel filter heater with condensation sensor |
D07.04-1210-11
Engine 642.992 |
70 | Fuel filter |
76/1 | Electrode 1 |
76/2 | Electrode 2 |
76/3 | Integrated electronics |
76/4 | Plug (to water suction) |
B76 | Fuel filter water level sensor |
P47.20-2257-11
Body
The condensation sensor for the fuel filter heater with condensation sensor (engine 642.8) or the fuel filter water level sensor (engine 642.9) consists of 2 electrodes. An integral electronic circuit is used for evaluation.
ENGINE 642.896
There is a heating element in the fuel filter heater with condensation sensor to improve the flow characteristics of fuel at temperatures < -10°C.
Function
The condensation sensor for the fuel filter heater with condensation sensor (engine 642.8) or the fuel filter water level sensor (engine 642.9) determines the electrical resistance between electrode 1 and electrode 2. The condensation sensor for the fuel filter heater with condensation sensor (engine 642.8) or the fuel filter water level sensor (engine 642.9) does not send an output signal if there is fuel between the electrodes.
If the water level in the fuel filter rises up to the electrodes, the electrical resistance between the electrodes drops. The drop in electrical resistance is detected by the integral electronics and read in from a condensation level of about 100 ml as a voltage signal by the glow output stage (N14/7) (engine 642.8) or by the CDI control unit (N3/20) (engine 642.9). The glow output stage (engine 642.8) reports the condensation level via the driveLIN (LIN C1) to the CDI control unit (N3/30) (engine 642.8). The CDI control unit reacts by transmitting a warning message to the display (A1p1) in the IC (A1).