Power steering issues (not a P/S relay issue)

'91 Turbo.
I know there are plenty of thread about this, but the problem seems to be slightly different in my case.
The power steering hardly ever work, and while the flicking the ignition on/off a few times before starting sometimes seems to make it work, it never works for more than a few minutes, at most.
When I turn the accessories on, I can hear the P/S pump being on and making lots of noise.
We tried to replace the P/S relay with another one and that didn't do anything. We also tried to bypass the relay altogether, and that still didn't do anything. So it seems like the relay might not be the issue after all (note: the P/S light doesn't come on on the dash)
 
Since the P/S pump seems to be working (even when it shouldn't be), it seems like the only other cause would be a faulty P/S ECU?
Or is there something else that could be causing this? (I want to be sure cause the P/S ECUs aren't super cheap (if you are selling a cheap one that's working, PM me :) ))

You say the power steering hardly ever works, is this observation from "feel" or have you tested it.  You mention that you can hear the PS pump on, and making a lot of noise.  Is this extra noise a recent event, or has it always been at this level.  Also, you've advised that the PS light does not come on.  This should light up when the ignition is turned to ON, then extinguish after 2 seconds.
 
First step to diagnosing this would be to make sure the light is working - if it doesn't in fact come on at turn on, check the bulb in the dash.  (Yes, I know, removing the dashboard is a PITA).  If it IS working (and it was just overlooked) there is a PS fault code procedure available.  Are you familiar with the method of "jumping" the data link connector terminals?  Codes you'll be looking for are likely to be 22 - "Excessive Current being supplied to PS Pump", and 31 "Worn PS Pump motor bushes"
 
I've only once heard of a PS ECU being faulty - but that car had had a serious electrical issue, and every controller had suffered from the voltage spikes!
 
Good luck with diagnosis, keep us updated with your progress . . .

do you have that position sensor thing on your steering wheel/indicator stalk?
 
also i had a small leak in one of the hoses for the power steering,when the oil level was normal the steering worked fine.as the oil leaked out it got harder to steer and the pump got louder...

 
 

alexv
But if the position sensor wasn't there, it would never work, wouldn't it?
 

pretty much.power steering system would start up,but turn off after a minute or so.the power steering ecu controls a power steering driver.the driver supplys voltage to the pump.at low speed cornering it gives lots of voltage to move the pump faster.at high speed cornering it gives less.so no sensor for ecu to look at OR its there but broken/not working
 
edit-pop your steering wheel off,if you cant see a cut out on the boss for the `plug` on that sensor to go in(the black plug sticks thru the boss to turn the sensor.the yellow wire coming off is for the horn ..)

 
 
 

I have had a look at this for alex and i think you're on the right track twomr2s im pretty sure all we were getting was the pump running for a minute then switching off but we tested the steering sensor according to bgb and it was flashing when turned more than 30° which is why we suspect the p/s ecu any help is appreciated.

Actually, I tried 4x today, and every single times the P/S worked fine for about a minute while driving, and no more after that until I switched the car off and on again.
I am guessing that my P/S relay was misbehaving and the replacement one we put in works fine but we didn't realized it because after a minute the P/S stops working anyway due to the missing position sensor (or troublesome P/S ECU?)?

Cheers mate, I was looking for the part number. I'll probably look for a used one...

About the indicator stalk.
I have the same problem and Terry at Road and Track told me that you have to change the assembly to fix this.
It looks like a common problem