Looking at purchasing a Acumen PD8 shift light, which apparently is an easy fit with just 3 wires, which consist of, earth, live and pick-up.

the pick-up being the one i wire directly into the rear of the tachometer.

This is my question; I have a Smiths Telemetrix Tachometer fitted, so for the experts out there which is the wire at the rear of the gauge i use for the pick-up for the shift light, or how do I test to identify this wire?


Peter