This tacho adapter converts the square wave tachometer signal from the LS based ECU into a signal that emulates the negative side of an ignition coil for the use of coil negative driven tachometers.
Perfect when using the factory clusters on older vehicles like Kingswoods, Toranas, 1st Gen Commodores, 80 Series Landcruisers and GQ Patrols.
The tach output may need to be reconfigured to suit the tachometer which is easily done in the ECU.