Tach signal for universal tachometer

Hello everyone

I am building a harness for 2jz vvti/Haltech elite 750. I know the ECU gets its rpm signal from the crank trigger, and I want to include a tachometer signal wire that can be ran to an external tachometer with a needle, like a universal one. Where would be the correct spot to splice in a tachometer wire that can be used as a signal wire? Crank trigger? Coil negative wire? (Using LQ9 COP coils) Thanks in advance.

You would normally connect the tacho to a aux output from the ecu (DPO in haltech terms) and that would be set to a "tacho output" function.

Ok great thanks. Never would have figured that out myself!