Fault finding tachometer

[Awally]

I am trying to find out, how to measure the output from the tachometer drive wire, that has been fitted on my alternator. With the engine running the tachometer indicates a fixed speed (no use at all) I get a DC voltage there of about 6.5 volts, and from the little I understand the tachometer works
, by measuring ac frequency, so has the tacho wire been connected to wrong part of the alternator. Any clarification appreciated

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[Awally]

It would be good to get some feedback, as I don't want to strip this thing down for nothing.
Thanks

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[donradcliffe]

Did you select AC volts on your multimeter?? The tach output is before the diodes, and the AC voltage should vary with alternator output level. My multimeter also measures frequency.

[Awally]

Sorry about that, did not get a notification of reply. All fixed now thanks


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