just got the hks timer 1,instructions in japanese no engrishh at all
have harness noted black to ground but other 4 brown and blue and grey unknown?
help ta

 

Grey = handbrake

Brown = RPM signal wire (splice into loom)

Blue = Speed signal (splice into loom)

you will need to locate these wires obviously, do a search for ecu pinout diagram or ask on here for car specific wiring.

Also grey wire to handbrake varies depending on how many wires you have to the handbrake on switch.