I am currently installing a remote start unit to my MB 230CE w124 1988, and need a "traditional" tach signal.

The tachometer signal in my car delivers +12V decreasing as RPM increases. The remote start unit needs a voltage increasing by increasing RPM (like when you have a triggering signal for each revolution).

Is there any sensor on my car which I can hook up to to get such a signal? I have heard about a diagnostic output, but not sure if this is correct. If so, could someone tell me the pin-numer for the RPM output?

Thanks in advance!

Anders Eklo - Norway.