Power steering pump electrical connections

Started by bobbe, August 2, 2022, 12:34

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bobbe

There are two connections between the Engine Control Module and the power steering pump's ECU. These two connections are PS-IDUP (which I'm not concerned with but through which the ECU tells the ECM to increase idle speed if needs be) and PSCT-EFI (through which the ECM can turn the power steering pump on or off):

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My understanding is that the ECM sends a high signal (5V) through PSCT-EFT to the power steering ECU when it wants the pump to run, and sends a low signal (0V) if it wants the pump to stop.

Does anyone know if this is correct? Could this be intercepted with a relay to allow manual control of the power steering pump? Or with an arduino or some other 5V microcontroller?

I ask because I'm interested in doing something like this, but instead adding a three way hydraulic control valve to allow me to keep power steering when needed (pottering around town, parking, etc) and to bypass the power steering pump when wanted (more enthusiastic driving). If I can also figure out how to turn the pump on and off at will (which I think the PSCT-EFI connection will do), then I can wire up a simple switch on the dashboard to control the whole thing.

Ardent

Certainly not as elegant, but you can always pull the fuse.
But a switch would be nice.

bobbe

#2
I could, though my understanding is pulling the fuse also stops the speedo, which is not so good. The other alternative is the key trick - turn it back one position while the car is moving and then return it to the on position - which also disables power steering. But then you can't turn it back on without stopping the car, switching the ignition off, and restarting.

Having one switch on the dash to bypass the pump and turn it off - and, just as importantly for switching between modes, turn the power steering back on without restarting the car - would be much easier

It's beginning to seem like the biggest obstacle will be finding a hydraulic valve that can cope with the power steering system's pressure without costing a fortune. Easy to get a manual one, but that somewhat defeats the purpose

Ardent

#3
Agree with you say, but
My speedo worked OK when I pulled the steering fuse.
If that helps at all.

Ardent


Carolyn

#5
We used quite a few actuator driven ball valves on the rocket car (1,000psi.).  The ball valves and servos come as distinct units and one had to make up the mounting plate to attach the actuator to the valve.  We only used two- way valves but a three-way vale body is readily available and both types operate through 90 degrees, so the same actuator will  do. We had loads of high pressure nitrogen on board, so we used pneumatic actuators.  You can get 12V actuators.

We also used shuttle valves, which will switch a hydraulic supply into two different outputs.. These used 12v solenoids to operate them but we only used them in lower pressure applications.

This one would do the job, but it's a bit big.  It can be adapted down or you can probably get it in smaller sizes:
https://tameson.co.uk/valves/ball-valve/electric/3-way/brass/bw3-034-aw1-r012dc-electric-ball-valve-3-4inch-3-way-12vdc-relay.html

RS have a few actuator/valve set-ups, but you might want to go to a hydraulics systems supplier to get the right thing for the job.

The prices are a bit frightening though!
Perry Byrnes Memorial Award 2016, 2018.  Love this club. 
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bobbe

Quote from: Ardent on August  2, 2022, 17:18Agree with you say, but
My speedo worked OK when I pulled the steering fuse.
If that helps at all.

Okay, interesting, thanks!

bobbe

Quote from: Carolyn on August  2, 2022, 18:03We used quite a few actuator driven ball valves on the rocket car (1,000psi.).  The ball valves and servos come as distinct units and one had to make up the mounting plate to attach the actuator to the valve.  We only used two- way valves but a three-way vale body is readily available and both types operate through 90 degrees, so the same actuator will  do. We had loads of high pressure nitrogen on board, so we used pneumatic actuators.  You can get 12V actuators.

We also used shuttle valves, which will switch a hydraulic supply into two different outputs.. These used 12v solenoids to operate them but we only used them in lower pressure applications.

This one would do the job, but it's a bit big.  It can be adapted down or you can probably get it in smaller sizes:
https://tameson.co.uk/valves/ball-valve/electric/3-way/brass/bw3-034-aw1-r012dc-electric-ball-valve-3-4inch-3-way-12vdc-relay.html

RS have a few actuator/valve set-ups, but you might want to go to a hydraulics systems supplier to get the right thing for the job.

The prices are a bit frightening though!

Yeah something like the valve you link might well work if I can figure out mounting etc. Thankfully since the valve will be on the return line I don't need to worry too much about pressure - 10 bar should do it, with a suitably rated non-return valve to prevent the high pressure fluid from the pump breaking the valve when the pump isn't bypassed. A solenoid valve rather than a ball valve might even be a (smaller and quicker operating) option, depending on prices.

So I reckon this is probably (hopefully!) achievable with a bit of research and thought and finding the cheapest suitable valve I can find.

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