On Tue, 21 Dec 2010 15:18:58 +0000, Nigel Molesworth
wrote:

On Tue, 09 Nov 2010 16:37:26 +0100, Dino
wrote:

Hany suggestion or link?

http://www.ybw.com/forums/showpost.php?p=2693853&postcount=10

Thaks for the link.

The above link do not show any details about wiring
connection.

I have decided to progress with a separate hourmeter and
leave the original tachometer only for the RPM display.

The reason is because of the uncertainty of hourmeter
connection. The VDO is connected to the motor with two wires
that carry the RPM pulse. It is my believe that RPM pulses
are internally analyzed to originate the "motor running"
information to the original hourmeter.

I'm progressing with a mechanical 12V hourmeter and a small
12V relay connected to the alternator output.