How can I tell what voltage a PPS steering rack sees at highway speeds?

[Insidious Surmiser]

My 88 apparently has a PPS rack, but none of the wiring, computer, or sensors. I want to just make a simple on/off circuit for it, but I don't want to put too much juice into it.

http://www.cygnusx1.net/Media/Supra/Library/TSRM/MK3/SR/SR_095.gif does this mean the rack is supposed to see negative voltage at higher speeds?

 

[jetjock]

Not that simple. Current controlled proportioning valve. That said, to answer your question, the PPS solenoid is normally closed and opens when normal polarity is applied to the + and - terminals. Although the book doesn't say it, under those conditions displacement of the needle will be appx .80 inch. Again though, if current isn't limited the coil will fail in short order...

 

[Insidious Surmiser]

oh, shoot. I smell a mad science experiment brewing.....