find the turbo oil return(silver braided hose)and follow it down to the side of the block,it gopes into a big hex shaped fitting,on top of this out of sight is the switch,i changed mine as it was pissing out oil,cost less than half an hour to do and cost less than a fiver
,tip.put the light under the car to see,use an adjustable spanner to unscrew it,set the jaws on the new switch before trying to undo the old switch and use your left hand to screw it out,much easier!good luck.