bigdel

We fitted a STACK oil pressure guage to my son's MK1 Focus RS which has been working perfectly for some months but all of a sudden it has stopped working. We still have oil pressure but the needle on the Stack guage just doesnt move.
there is power to the guage, and the sender has a good earth (mounted remotely so has it's own earth feed)
I've put a meter across the -ve & +ve terminals on the sender and can see there's some resistance, but not knowing what values I should be measuring (resistance or voltage) is difficult to know whether the sensors working correctly or not.
anyone got any idea what I should be measuring across the sender?