Just want to know where the PS vehicle speed sensing gets it signal from... I know there's a ps cpu... but what is needed for it to work correctly? Is the main CPU needed? Will a standalone nullify it? Also, i'm guessing the pump is the one that controls the pressure after some x/mph and not some other device in the rack? Thanks ahead of time.

 

The PS has it's own computer, and works totally seperately from both the ECU (engine) and CPU (body functions). It gets a speed signal from a pulse generator in the speedo. The line pressure is controlled by a computer-controlled stepper motor that alters the pump's output pressure.

 

speed sensor signal for the cruise and power steering computer comes from the speedometer in the gauges.

 

great... is this stepper motor outside the pump or inside? I read something about signals from the leading coil... but don't know if this refers to this type of system. To lay it out, and put it short, the rotary is out, along everything related to it. I want to retain the mechanism, whether by using the OEM pump/hardware, or by modifying the new non-oem pump to interact w/it.

 

You might want to dig up the wiring diagrams from the Factory Service Manual. Any questions you have about what's wired to what will be answered by those.

-=Russ=-

 

What year car?

This all applies to the 91 S5. Anywho, lead 51 comes from the speedo...


In this picture you will see the three things it feeds. Cruise, PS, and passive belts.


And no, standalone does not mess with it.
https://www.rx7club.com/showthread.p...ighlight=speed

James

 

The fc s4 online manual for some reason doesn't have any info on the electronics of the ps (looked in ps and body electronics). If I were to "upgrade" to s5 cluster, would the signal remain the same to the s4 vehicle speed sensing ps cpu? In other words, let's say I pick up an s5 na engine speed sensing cluster, will this cluster have provisions for the s4 vehicle speed sensing stuff?

Thanks a lot guys.

 

They send the same signal

So yes, if you wanted to go with the smaller gauges of a S5 in a S4 car it would work fine after you re-wired the dash harness