Tachometer problems

[kwale86]

I recently purchased a speedometer and tachometer form ebay for a 1999 Honda Magna. The speedometer works fine but the tachometer is not working.  I am getting voltage from bike to the connector.   I am not sure on how to fix it or what I can do.  Any suggestions would be greatly appreciated.  Thank you.  Misty (Kales wife)

[kwale86]

I am getting 12volts (= to battery voltage) with the ground unhooked from the tach with the engine off.  When it is started, with the ground still unhooked, it drops slightly, then when i raise the rpms, it progressively drops to about 8 volts at pretty high rpms.  with the ground hooked up, the voltage stays at abotu 1.5 volts whether the engine is off, idling or revved up.  I hooked the tach up directly up to the battery momentariy & as soon as I connected it the needle pegged all the way.  I checked the resistance between the tach connections & it reads about 10 ohms one way only.  no continuity the other way.  I connected an alternate ground to make sure that was not the problem but still nothing.  I dont know what any of these readings are supposed to be so maybe one of you electronic geniuses out there can help me out.  I really dont want to buy another tach but it is looking that way.   The bike had been wrecked there was no tach on it when i bought it so I dont know if it was working before the wreck or not.
Thanks,
Kale

[MagnaMan]

Perhaps you can meet up with another Magna owner and see if you get similar readings from a bike with a working tachometer.

[RedMagna]

kwale86 please check your PM, as I have an OT question for you.  Thx.

[silveradocowboy]

I can only give reference from a vintage Magnas manual but maybe it will help. The manual also says to use a known working tach as Jesse already mentioned. Check continuity from the yellow wire at the tach connector to the yellow wire on the 1-3 cylinder coil and then to the 1-3 cylinder spark unit. There should be continuity. If there is continuity replace the tach. If there is no continuity repair the circuit.