I want to pull my entire engine wire harness just the stuff that controls the engine; to intall my Haltech E6K.

I would still like to have all my stock indications in the intrument cluster. what wires are connected to the engine ECU that is connected to the instrument system? For example; what wire is use for RPM indication?

 

What generation?

I pulled the engine harness on my FC and I believe all I had to do was remove some pins from the ECU connectors, remove the windshiled wiper motor wires from the harness, and run a wire from the water temp sensor to somewhere in the car.

To answer your question about the tach, it gets its signal from one of the coils and you shouldn't have to do anything special.

 

Ok sorry its for a 3rd generation car

For the tach it makes sense to me to get a signal from the one of the coils or the crank trigger.
I will just do some more research.