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