Tacho Output Adapter by Haltech This Tacho Output Adaptor converts the square wave tachometer signal from the Haltech ECU into a signal that emulates the negative side of an ignition coil for use with coil negative driven tachometers. Features For use with coil negative driven tachometers Environmentally sealed and vibration resistant for underhood mounting Compatible with 1-12 cylinder engines Benefits Senses current on the coil positive wire and converts it to a 12 volt signal output Please Note: Requires Spare DPO on ECU Applications Universal What’s In The Box? 1 – Tacho Output Adaptor Matching Set of DTM 4 Connector plug and pins Warranty Haltech Limited Warranty