Component description RPM sensor Housing: grey Coding A Housing: black Coding B 1 2 2 1 Plug connection RPM sensor (1) Plug connection Auxiliary rpm sensor (2) Function The rpm sensor consists of a permanent magnet and a coil with a high number of windings. The magnet “touches” the rotaring component to be measured, normally a crown gear or grooved ring gear; with its magnetic field. With the EDC MS5 system, there are 6 grooves on the flywheel. When a groove passes the sensor, the magnetic current is reduced. This generates an induction voltage in the sensor coil which is measured by the electronic control. The distance between the sensor and the grooved ring gear is approx. 1 mm.
Two rpm sensors are required to ensure reliable operation of the EDC system. Both rpm sensors are installed in the flywheel housing. A distinction is made between the rpm sensor and the auxiliary rpm sensor. The rpm sensor is installed in the flywheel housing such that an rpm pulse is triggered 105 after TDC. The auxiliary rpm sensor is installed in the flywheel housing in such a way that an auxiliary speed pulse is triggered 185 after TDC. The signals of the auxiliary rpm sensor are used only for redundant engine speed sensing. Caution: Do not confuse installation locations of the rpm sensor (1) and the auxiliary rpm sensor (2), nor the “+” and “–” wires of the sensors. 17