Hey, Anyone know how the factory in dash tach operates in a '69 Mustang? I dont see a wire going to the negative side of the coil. I have a wire diagram and it doesnt show a tach wire at the coil either. Mine works, but I dont know how it could, and I want to use it with a Mallory ign amp. I dont want to burn it up wiring it wrong. Thanks
The factory tach connects between the ignition switch terminal (red-green) and primary resistance wire (pink) feeding the plus side of the ignition coil. Basically it's in series with the primary ignition circuit. In block form:
Ign sw---red/gr---Tach---pink---Resistance wire---Connector---red/gr---Coil+
HTH
-- Mike
93 Cobra(Wishing he was in Nashville for the 40th)
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