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Old 10-01-2012, 11:56 AM
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Default Grey wire on msd 6al

Hello. I have a 83 porsche sc
All the diagrams are great though there is no mention of where the grey wire off the msd harness goes.
I suspect it is the tach output wire.
Is that right?
If so would it connect to the car's harness at TD?

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Old 10-01-2012, 02:49 PM
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msdtech1955 msdtech1955 is offline
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from page 2:

The MSD Ignition features a Gray Tach Output wire that provides a trigger signal for tachometers, a
shift light or other add-on rpm activated devices. The Tach Output wire produces a 12 volt square
wave signal with a 22.5 duty cycle.
Some vehicles with factory tachometers may require a Tach Adapter to operate with the MSD. For
more information on Tachometers and MSD Tach Adapters, see the Tachometer Section on page 6.
If your GM vehicle has an in-line filter it may cause the tach to drop to zero on acceleration. If this
occurs, bypass the filter.


Tach output wire. Connects to the tachometer trigger wire or other
rpm activated device.
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