I would like to install a racing style LCD dashboard with RPM and current gear indicator on my 997 C2S manual transmission car.

To do this, the unit needs a tach signal and the vehicle speed signal. It then does the math and computes the current gear.

I already have the tach signal from the ECU (it is the ignition signal to cylinder 1). I just need the vehicle speed signal.

Here are some possibilities on the location:
1. VSS signal around the PCM/center console area used for the navigation system. Not sure if my car has this, and it may be inaccurate, too.

2. ECU. There are several pins that seem to state "speed sensor". They are:
https://www.6speedonline.com/forums/...4&d=1325732520
"speed signal from ABS control module"
"speed signal output"
"Signal A, speed sensor"
"Signal B, speed sensor"

Does anybody know which I should use? Is it Pulse Width Modulated, Pulse Frequency Modulated or perhaps just an analog 0-12 Volt signal?

 

My guess would be "speed signal output"

 

Yeah, I'll have to hook it up to my oscilloscope and record the signals as I'm driving around.

There is an aftermarket gear indicator called the Engear:
http://www.starlane.com/vedit/15/cro...sp~idprod~1072

It's not clear exactly what type of electrical signals it wants. It's worth trying, however. If it doesn't work, I'm thinking about making a simple version custom for the car with some customer micro-controller code and selling it on eBay or Amazon.

I like having a gear indicator and RPM shift lights so that I can drive fast without worrying about making a costly mistake.