Add a tachometer-electronic iginition

Old 10-31-07, 03:03 PM
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Add a tachometer-electronic iginition

Just for fun. I want to add a tachometer to a vehicle(s) with electronic ignition. The older "normal" autos it is only required to attach the "tach pickup" to the negative side of the coil. Since the electronic ignition systems now use "transistorized" or "capacitor" discharge--how do I determine the correct wire to connect to the "tach pickup"? Would the source be from the coil or from the distributor?

Old 11-01-07, 09:41 AM
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I would probably source the signal from the distributor. When you hook up a timing light you always use one of the plug wires, so that seems like the most reliable place to grab a signal for an external tach.
Old 11-01-07, 10:36 AM
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Most electronic ignition modules have a 'tach wire'. You just need a good electrical schematic of the vehicle wiring to find it. Some libraries have a set of vehicle schematics published by Motors Manuals (name??) or something close to that. Maybe an automotive book on ignition systems would be a source as well. Good luck.

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