Indentify & located the ECU wires arrangement

[riq]

Hello to all sifus out there...

Newbie here...

I need some help regarding how to indentify & located the ECU wires arrangement...
I drive a Satria with 4G13P & SVDO ECU..i know where is the location of ECU in my car...
The problem is, i don't know which wire that carry signal for O2, RPM & KM/H...

For your information, i want to install HKS Type-1 TT & my DIY AFR meter by myself...

Is it true that most wires in ECU has in & out?
A friend of mine said that if we want to tap a wire from any meters to the ECU...we should tap at the "out wires" one?
This is to avoid interuption to the sensors maybe...

Thank you very much for you time here...mind to help me please...