yellow wire on HKS turbo timer

[bobmac]

as title guys, i had a greddy TT fitted but all it did was count down all the time, got very annoying after a while trying to turn off the car only when the TT hit + one minute, anyway kept looking on fleabay and got hold of a HKS one ( not sure of model) this has an extra wire pretty sure the red, green and blue go to the same spot on the greddy harness, however i dont know where the yellow wire on the HKS one goes to, any help appreciated thanks