I'm trying to find information on wiring for the 3-port power steering pump to enable speed and engine sensing in my FB with an S5 swap. Right now my power steering setup is installed but basically not working. Specifically, the 6-pin "stepping motor" connector that the wiring diagram just shows going to some kind of steering control unit. I've looked through factory wiring diagrams but can't find information on how these wires work and which is which so I don't know how to hook it up.




My car is an 84 GSL-SE which had speed-sensing power steering also, and ideally I could hook that into the S5 pump somehow. On the GSL-SE the steering box has just a 2 pin connector coming from the steering control unit under the dash. Any help is appreciated

 

the FC's (mostly) had a stepper motor in the pump so they can very the assist, its completely different from the GSL-SE or practically any other car.

 

I can't find much info on the GSL-SE system either, but it also has a separate steering control box with an input from the gauge cluster (speedometer) for sensing vehicle speed. I assumed that steering box also had a stepper motor and I could use the same GSL-SE steering controller for the the S5 PS pump (at least for vehicle speed and not engine speed)?

Alternatively, if there is a way to just force the stepper motor into one position that would help. Right now I have all the power steering parts installed but almost nothing is happening. It still feels a lot like manual steering

 

Alternatively... if I can get a Power Steering Control Unit from an FC and wire power into both the PSCU and stepper motor like the daigram shows (B/G wire on right), the only piece missing is the instrument cluster connection (G/R). Since my GSL-SE also has a PSCU that is also fed from the instrument cluster, maybe I can just swap that connection onto the S5 PSCU? Any idea how I could determine what that signal needs to look like and whether my GSL-SE's signal is compatible with an S5 PSCU?

 

How does the bypass line act? Does the stepper add more pressure as speed increases to reduce the assist and have a heavier feel or the reverse and drop the line pressure?

 

i think it drops pressure, but http://foxed.ca/rx7manual/manuals/Tr...ing_System.pdf

 

Thanks for that training manual link. There is a lot more information in there than in the service manual or wiring diagram.

Last night I did more reading and learned a few things. First, based on the cruise control unit documentation, in an FC the speedometer output is a range between 0v and 10v. I assume this is the same thing I'd get in the speed input to the power steering control unit. Since the steering wheel input is just a potentiometer, and since the control unit really only needs the vehicle speed input to work according to their failsafe table, I may still be able to get an FC controller to work in my FB as long as I can confirm the FB speedo output is also in a 0-10v range. I could even install my own dial potentiometer in place of the steering position sensor if I wanted to adjust the power assist on the fly as long as I can find the total resistance across that potentiometer. Make sense? Below is a diagram of how I am thinking to install it




Next step for me is to see what output the FB speedo is giving since I cannot find it documented

 

i think you need the engine speed signal, but that is pretty simple, you can use something from the tach, it beeps if you don't.

the speed signal should be the same, or close enough. and if you wanted to dial it in, a potentiometer might be a good idea

 

It beeps huh? That's fun... I'm sure I could get the engine speed but that may require digging more out of the dash than I wanted, like the cluster. I'll see though. I first want to somehow confirm I can get a signal from my tach that the FC PSCU would recognize. And I still need to figure out the total resistance of the potentiometer in the steering angle sensor – does anyone have one laying around who could check?