[Vwdiesel] Diesel Tachometer in an older VW

Roger Brown r.c.brown at ieee.org
Sun Aug 24 12:44:02 PDT 2008

Yep, a gas tach will read out much higher when hooked to a W-termianl signal:

Tony and Lillie wrote:
> OK, Thanks Loren and Kurt. 
> Now I'm begining to understand. I used the complete instrument cluster from the gasser 2.0 90 4-cylinder. So, it's not just a plug and play thing. I guess I was under the impression it was that simple. DOH!!
> I also have to figure out how to drive the electric speedo, but that's not as big of a deal at this time. Just one thing at a time.
> Tony
>   ----- Original Message ----- 
>   Subject: Re: Diesel Tachometer in an older VW
>     Well, a gas tach gets 2 pulses (for a four cylinder) per crank 
>   revolution.  An alternator is putting out however many pulses 
>   (number of windings or maybe a multiple of the number of 
>   windings) per revolution but it's turning at 2 to 5 times faster 
>   than the crank!  The newer it is the faster they tend to turn 
>   them for more amperage.
>     There ARE workarounds. I just don't know them.  I know Jake 
>   Russel built one.  There's a dab of circuitry and a pot to adjust 
>   it.
>       Loren



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