Oil pressure buzzer and light keeps going off

It first started happening on the way home from the AGM, but the car drove fine and it was not that frequent and was random.

As a starting point the garage has changed both low and high pressure switches.

However this weekend the buzzer was going mental on the way to and from edition 38.

It just stayed on constantly for five minutes and then randomly went on and off and various speeds and I couldn't find a pattern to are it come on or off.

Please help as I don't know what to do, it drives spot on, but did randomly stall a couple of times and struggled to start in traffic and was then fine again so that might just be a random issue as it was a very hot day on Sunday…

Any thoughts or suggestions please, do I change oil pump, do an oil and filter change or something else…

Oh it's a 1.8 gti on a 91 and is a storyline cab if that makes any difference

The oil pressure warning buzzer should activate if the oil pressure fails to reach 2 bar at 2000rpm.
So, if you turn on the ignition you shouldn't get a buzzer, if you start the engine and leave it at idle you shouldn't get a buzzer,
if you then raise the engine speed until you pass 2000rpm the buzzer would sound (assuming the oil pressure was low) and then stay on when returned to idle. When you switch the ignition off and then back on the sequence should be the same ie buzzer off until over 2000rpm.

If the buzzer is being activated it could be;
1. Low oil pressure caused by thin oil, worn oil pump or blocked oil pick up
2. Oil pressure switch faulty (you've changed yours so you could rule that out)
3. Oil pressure switch wiring faulty (this is what caused my problems)
4. L-shaped circuit board in the dash faulty

If your buzzer is coming on randomly (not over 2000rpm) it would point to the circuit board being dodgy.

If you are able to check the oil pressure that would be a good start; at least you would know that you're not going to do any damage by ignoring the buzzer.

Have you ever had the dash apart? There would be an L-shaped circuit board on the back of the clocks; it has a small buzzer on it (looks like a small relay).

Like this:

http://i288.photobucket.com/albums/ll199/fatrbt/OilWarningPCBoard.jpg

check the dash earth on the side of the head too, its the brown/white wire. the high oil pressure switch is in the filter housign with a blue/black wire, push the rubber boot up the wire so you can check condition of the wire under the boot and the spade. the high pressure switch should be white in colour, its the larger one of the 2

Thanks guys, 

It was buzzing at standstill every so often ie under 2k rpm.

I will get my trusty mechanic Mits530 to take a look at the wiring.

If that's all fine do I look at replacing the oil pump first or the circuit board behind instrument cluster and I'm guessing I'll have to buy a used part..

if its coming on below 2k then its a wiring or clock fault, but might want to have pressures checked for piece of mind