5KCSTQ oil warning light?

[hill@eng.pko.dec.com (Paul Hill 223-2154)]

My 5KCSTQ has started to display the oil warning symbol in the multi function
warning window (the little oil can in a red triangle) whenever the engine RPM
drop below about 1200.  I checked the oil level and it is fine.  While cruising
it is fine, at idle or trickling to a halt at a junction or in traffic etc. the
warning light comes on.  If I rev the engine to 1500 RPM the light goes out.

This started happening suddenly.  I have never seen the oil warning light
before.  This suggests that something has failed, and that this is not due to
incremental wear on the pump: but then I could be misinterpreting that?

Any suggestions?

Thanks,
	Paul