Oil pressure warning at 2800 rpm, 1988 90Q

[radek at istar.ca]

Hi everyone;

After changing the clutch (and a few other things) on the 90Q, I took  
the car on the road for a test drive.  It gives me a loud beep and a  
flashing oil pressure symbol every time I exceed 2800 rpm or so.  The  
light stays on as long as I keep it above 2800, disappears only if the  
engine slows down.

My understanding is that there is a low and a high pressure sensor on  
the car, but looking at the engine block I only see one, brown.  Is  
the pressure sender (the big barrel) acting as the high pressure  
sensor?  It's disconnected right now, actually the terminals broke off  
due to rust, awaits fixing.

I would greatly appreciate some sort of reassurance that it's the  
sensor, rather than actual low oil pressure!
Thanks!

Radek
88 90Q