Plea for help! I can't turn off my 560Sl

Group, My 1986 560SL will run after the key has been turned to off. Turning the key off and on has no effect on killing the engine or shutting down the instruments. After a while the car will die on its own and
the instruments will as well turn off. It my take an hour or a few minutes. After this the car will start and stop fine. The problem is that it only pulls this stuff when away from our house and usually when my wife has the car to herself so I have not been able to diagnose it until last night when my wife pulled the car into the garage and it kept running when she turned off the key for the first time at home. With the engine running I removed the steering wheel, instrument cluster and then was able to unplug the ignition switch. The car continued to run while the switch remained unplugged. I then started to investigate the relays located around and behind the glove box to see what my be ingizing the engine ignition when suddenly the car died. Much to my disappointment the car starts and stops normally now and I now have no way to continue the search for the problem until it happens again. I have looked over the engine wiring diagram and can concive of several ways different relays could back feed the run terminal of the ignition switch and there for am left to only guess at the problem.
I am hoping that someone who is familiar the ignition system in this car can tell me what can keep the engine and instrument cluster energized while the key is in the off position other then the key its self?
Thanks, Bruce Buchanan
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Wow... a gas engine that continues to run after key out?
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Tiger wrote:

I've heard about that, I believe they call it 'dieseling' here. I believe I heard it's caused by (carbon?) deposits in the combustion chamber that glow when the engine runs and keep it running even when the normal ignition spark disappears. Or then again, maybe the ignition lock is faulty ;)
Ximinez
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Its not dieseling, I am saying the care keeps running, gages and all like the key is still on, but as I said the car keeps running with the key switch unpluged, its not the switch. Its somthing else sticking like a relay. Bruce B
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Do you have remote start from aftermarket alarm?
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Yes. I have seent his before but not on a Mercedes. I had one car where I was able to get home from work and be eating my dinner before it turned off. Then it might chug a few times and strat up all over again. The only way to stop it definitley was to disconnect the battery. That was in the days before radio key coders and complex electronics.
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