S13 start signal wire

[Sketchysil]

Hi all
Im trying to figure out what wire the start signal wire is? i can't seem to find anything about it. I am trying to wire it into a rb25 harness . Its a 1991 S13 that came with a sr20de.

Any help is much appreciated!

[zombiewolf513]

Should be orange on the little white or brown plug by the ecu