Last update: Aug 8 2014
Driving the tachometer is the EV West Precision Tachometer Sensor, mounted at the front of the motor. To my surprise, the exciter wheel is made of aluminum. Prior to using this sensor, I incorrectly thought that inductive sensors detected only ferrous metals. In fact some inductive sensors detect nonferrous metals as well. This sensor works perfectly and looks great. The 2006 Subaru Impreza WRX tachometer requires two 12V pulses per rotation.
Before the conversion, the tachometer signal was produced by the ECU. Therefore, the wires from the sensor are routed to the location of the ECU. The power to the sensor is connected to a convenient ignition switched source - the fuel pump relay coil.