COMPUSHIFT Speed Sensor Inputs

There are two types of speed sensor inputs on COMPUSHIFT controllers. This document explains how they work, how they differ, and their intended purpose.

Two Wire Speed Sensor Inputs

These inputs are generally used for transmission speed sensors. There are two inputs per speed channel: high and low. The low side, when used, provides 1.4V supply to a variable reluctance speed sensor. The high side input triggers at about 2.1V during a rising signal, and about 0.7V on a descending signal, giving some hysteresis and noise rejection. The low side input can be left unused if he high side input is to trigger relative to ground at the above levels. If the low side input is connected to ground, the high side trigger levels will be reduced by about 0.7V.

Single Wire Tachometer Input

This type is available on pin 80 on a COMPUSHIFT Sport or Pro controller. This input has protection against +/- 100 volts and triggers at about 5V. It is intended to be connected to a points type ignition system, ignition system tach output, or a 0 to 12V square wave signal.