ENGINE | 646 in MODEL 909 |
N07.16-2070-08
70 | Fuel filter | B76 | Fuel filter heater with condensation sensor |
Location
The fuel filter heater with condensation sensor is inserted from above in the fuel filter.
Task
The condensation sensor for the fuel filter heater with condensation sensor 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.
70 | Fuel filter |
76/1 | Electrode 1 |
76/2 | Electrode 2 |
76/3 | Integrated electronics |
76/4 | Plug (to water suction) |
B76 | Fuel filter heater with condensation sensor |
P47.20-2257-11
Body
The condensation sensor of the fuel filter heater with condensation sensor consists of 2 electrodes. An integral electronic circuit is used for evaluation.
Function
The condensation sensor of the fuel filter heater with condensation sensor determines the electrical resistance between electrode 1 and electrode 2. The condensation sensor 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 the 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 CDI control unit (N3/21). The CDI control unit reacts by transmitting a warning message to the display in the IC (P15).