oil pressure buzzer sounds when I switch on ignition

Almost finished my golf, but now, when I switch the ignition on the oil pressure buzzer sounds. Obviously isn't low oil pressure as I haven't even started engine. I shall investigate and report back. Incidentally the "buzzer" is a rapidly oscillating relay not a buzzer that we recognise these days. Actually, I think I will discard it all and fit an oil pressure gauge.

Have a look at my response on this https://vwgolfmk1.org.uk/forum/index.php?page=topicview&id=helllllpppp%2Foil-cluster-light-and