no current detected?

I am installing a valet a 554r on a 1997 Lexus es300. I finally! located where I was instructed to tie in the tach lead. It appears to be some module that has something to do with the speed control of the vehicle. There is a 4-wire plug on the side of it and I was told it would be either a grey wire or a WHITE/ red wire. After finding neither of those colors I used my fluke muti meter to see which wire was carrying the 1V-6V load I was looking for. Well with the car running I was unable to get voltage from any of the wires.

I read in a post while trying to solve this problem that you can use a fuel injector wire as long as you use the non common wire? Has any body had luck with this route? Or is this tie in necessary at all? I don't know but I have every thing else tied in and really don't want to power it up unless someone with a bit more experience in this department gives his 2-cents worth. Thanks much for the help guys

If it too fast your Too old...