1992 dodge mins diesel still runs after being turned off. How do I rule out its not the shut off solenoid?

well 9 times out of 10 it prob is your solenoid switch...i had a recent problem with my truck where it wouldnt crank and we ruled that out by trying a new solenoid....a good easy way to check is turn your key to the off position...dont crank it up and then take off the top plug and touch a metal object from the top to the side( the bolts) if it cranks in the off position it is either your wiring or switch...after you find out this just take it to your local mechanic and he can help you from there