W210, 1997 with straight six, car runs with key out!
 

Hello everyone,

I have a 1997 E320 with the mechanical key. I replaced the car battery last month and thought this solved the problem. Had some electrical gremlins.

Well my wife came home, parked the car took out the key and car is still running. I disconnect the battery and the car is still running?!?!!! What the?!?! Yes with the battery disconnected the engine was still going, never seen that before! So I took the key and turned it to start the engine again, note I was not getting any power to dash lights, air conditioning etc. And yes it made my starter work and this killed the engine. I am concerned, do this a few more times and I will be buying a starter. Any ideas? need new ignition switch? ECU? any relays related to this problem? Any help before I take this to an independent and grab my ankles.

Thanks everyone!!!

The alternator will certainly supply enough current to keep the engine running without a battery, but it's still a very bad idea. Don't use this as a diagnostic any more, lest you burn out some rather expensive electronic parts.

I've never seen this before, but the ignition switch is probably the most likely culprit. It could also be a short in the wiring.

:eek: Stephen King's "Christine" comes to mind......

I had a 95 E 320 in a few days ago. Engine would sometimes keep running with key out. Dummy lights would come on when the door was open and key out. wipers would run when in off pos. finally caught the problem when battery was not getting a charge and then a crank but no start. Replaced the overload protection relay. They do seem to cure everything from flat tires to world hunger. take a look at it.
Paul