Speed Sensor

Speed sensor consists of a magnet driven by speedometer cable and an on-off reed switch which is actuated by a magnetic field of the magnet. Reed switch produces six pulses (four pulses on 2T-C) for each revolution of speedometer cable. At 60 MPH, 6, 000 pulses (4, 000 pulses on 2T-C) are produced and fed into speed marker which then actuates that unit.