Transmission Controlled Spark: Description: Speed-Sensor

Consists of a magnet driven by speedometer cable and an on-off reed switch. The switch is actuated by a magnetic field of the magnet. Reed switch produces 6 pulses (18R-C engine except Celica and F engine) and 4 pulses (all other engines) for each revolution of speedometer cable. These pulses are fed to either the speed marker relay or computer.