This is a touchy subject
Go to the Ask an Owner Page....Basicly the ignition switch only activates the starter and guages. When you pull the engine shut down BEFORE youturn off the key, you should hear an alarm for low oil pressure, just as you do when you first start the engine. The order you do it makes no difference to the engine, because a diesel only needs electricity to turn the starter. You must never, according to Yanmar, turn the battery selector to off before you stop the motor. You can fry the alternator if you do...Hope this helps