tacho to newer OEM's

[Davek]

Hello guys
MS sends a 0-12v square wave signal out the tacho wire #26--MS3x. Firstly is this correct. Secondly do most or any late model OEM's need this signal for the tach to work properly? Or do we all need to these signal adapters I know nothing about.
thanks guys
as you probably figure I like to get a junk yard tach and place behind my 73 Datsun 240Z tach face.

[dontz125]

First - not quite. The MS3X Tacho pin is a ground switching output ; you'll need to add a pull-up to 12v to get the desired square wave.
Second - some of them. Some of the REALLY new tachs run by CAN or similar. Check the wires to the tach; 3 wires is probably square wave (or coil pulse if old enough!); 4 wires is probably digital. Of course, that doesn't include wires for background lamps or idiot lights ...

[jsmcortina]

Don! Check the schematic!

James

[Roofy]

First off, I apologize for the reply to this old thread, but I had this same issue with my car, a newer GM. 2005 Sunfire to be exact. I needed a 5v square wave tach signal to the PCM, and the MS3PRO sends a 12v signal. I just used a TO-220 package 7805 Voltage regulator setup on a small breadboard. 12v in, 5v out. Works great.