legacycentral bbs

What's the function of the electrical connector on the JDM PS pump?
I'm guessing it has something to do with the "sporty steer" button the Legacy RS had. Does it monitor or control steering assistance? Seems like the rack would have to be the part of the system that's variable.

I think it's just a pressure sensor. Some (most?) US-market Subarus have them, too, I think. Just not ours.

Yeah, it looks like one of the OBDII trouble codes is related to power steering pressure. So it's probably just for a pressure is good/shitty signal. I want to use it somehow.


On a related note, if your PS pump starts making noise, replace it at once. I waited and it seized on the freeway, luckily not in a turn. The belt it shares with the alternator burned into a million sticky chunks all over the engine bay. Scraping burned belt remains out of the crank pulley isn't my type of fun.

FYI the JDM pump has a different reservoir gasket. It's conical and countersunk rather than a flat counterbored ring.

What would you do with it? I think ECUs meant to work with it use it in the idle control algorithm.

I want it to tell me when the pump is starting to go bad. I don't want to rely just on how much noise it makes. That's just an idea, the pressure switch probably can't be used for it. A measure of the pulley's resistance would be better.

If it was for idle control, would that be used to keep the RPM above what was required for a minimum pressure?

I think the idea was that by measuring the pressure the ECU could know when you were using the steering and if the VSS said you were moving slowly it could bump up the IAC duty cycle to give you the assist you needed.

I thought the purpose was to vary steering assist based on engine RPM, the blanket assumption being that the higher the engine RPM, the faster the car is going, and thus a decrease in need for steering assist.

I know the PS pump I pulled off my EJ18 Impreza engine (from a 95 I believe) has a sensor on it. If I remember - which I probably won't - I'll look at it to see if the plug is similar to the one pictured.

But how would it electrically vary assist?

From the look of it I’d guess its just a temp switch, but it could be a valve to control line pressure. My Suburban has the variable assist PS and it has a duty solenoid that regulates the pressure.

Gary

Its the pressure sensor that is used to bump up the revs when you are drysteering, say like when you are in a parking lot.

Yeah it's gotta be that way, because the way the pump is designed, there's not really any way to adjust assist pressure.

The only way to adjust it is to use a different spring that controls line pressure. So it sounds like they designed the system to be slightly underassisted, and then used the pressure sensor to bump revs when backpressure on the pump increased.