Engine keeps running with ignition key out
 

Hi everyone,

I am a newbie here, and have owned a w123 230E for about 6 months. The car is an absolute joy to own, but has recently developed a very odd problem where the engine refuses to shutdown even after I remove the key from the ignition.

I have done search for this and found lost of threads concerning similar problems, but its almost always with diesels and usually caused by a vacuum leak. My car is petrol, so I expect the problem is electrical and not vacuum related. Here are the symptons:

• When I try to shut down the engine it doesn't shut down, and I can pull the ignition key out and it just keeps running for as long as I care to wait. The only difference is that with the ignition switched off it idles at slightly higher revs - at about 1000 rpm rather than than the usual 750 odd.
• If I then open the drivers door whilst the engine is running on like this (key out of ignition) a couple of the warning lights illuminate on the dash. I think its the battery light, the fuel warning light, and the handbrake light - the ones you usually see illuminated when you first switch on the ignition.
• Now this is the really odd one - when I close the drivers door again the engine stops! This happens every time. I am still using the car at the moment, and when I go to shut down the engine I just remove the key from the ignition, get out of the car (with the engine still running), and when I close the drivers door after exiting the car the engine shuts down!

If anyone can offer any advice or suggestions about what they think may be causing this I really would be very grateful. I'm just stumped!

Many thanks for your help!
Charles

I've got an 83 300 diesel and when I bought the car I was able to remove the key completely and the car ran. It wasn't a vacuum leak, but was due to a broken-then-modified ignition switch, so you may have an internal mechanical problem with the ignition switch.

I'd do a bit more toubleshooting or collect some data points:

When the key is in the ignition and it's running normally, what happens with the open door? Do the same lights come on, or is that only when the key is out?

When the key is out and the engine running and the door open, do you get the "key still in ignition" buzzer, like the sensor for the key is broken? If the engine isn't running, the key is in and the door open, do you get the buzzer? I'd try to do things that can help diagnose a mechanical or electrical problem.

If you don't close the door, but only push on the sensor/switch, does that shut the engine down? That might mean there's another electrical issue. If it only does it when you close the door, then maybe there's a vibration/motion that causes the ignition switch to click closed.

And welcome to the forum.

Thanks for the reply Yak - that's very helpful, and I have tried a few extra tests like you suggest. My car doesn't appear to have a "key left in ignition" warning buzzer - well not one which works anyway - but it does have a "left the lights on" warning buzzer which sounds if I open the drivers door with the keys out of the ignition whilst the lights are on. That warning buzzer still works even though the engine is still running when the keys are out of the ignition.

I also tried pressing the sensor/switch near the door hinge which is triggered by the door closing. There are two such switches on the drivers side, and just one on the passenger side. The upper most switch on the drivers door causes the "lights left on" buzzer to sound and also the courtesy light to come on and go out when entering/exiting the car. If I operate this switch manually with engine running/keys out of ignition whilst the lights are on, the warning buzzer will stop as expected. Also, I can switch off the courtesy light by holding the switch in, so it looks like this upper switch is working.

As regards the lower sensor/switch, if I operate this switch manually whilst the engine is still on/keys removed from the ignition, then the engine immediately shuts down. That was a great suggestion to try this to eliminate vibration as the cause of engine shut down, and I can confirm that it is definately this lower sensor/switch which is shutting the engine down. I haven't a clue what function this sensor/switch normally performs. The switch is only present for the drivers door, and doesn't control the courtesy light nor the "lights on" warning.

Do you have any ideas what that lower door-close sensor is normally for? Any other suggestions of any diagnostics I might try?

Many thanks for your help. I think I will probably be spending tonight trawling the Internet for any clues about what the fault might be. I thought it might be a faulty ignition switch - I can see how that might cause the engine to not shut down, but I can't see how it would make that lower door sensor shut the engine down! Electrics are so weird sometimes!

Yak, I have just thought. You mentioned a warning buzzer for the keys being left in the ignition - well this warning buzzer doesn't work on my car, but maybe that is what the lower door sensor/switch operates? If it is then that would explain the link between this switch and the ignition switch, and why this switch might be shutting the engine down in connection with my eltectrical fault. Perhaps I do have a faulty ignition switch. Any ideas?

if you take the key out are you still able to drive the car? try depressing the brake pedal when you take the key out.

I'm not up to speed on Irish geography or traffic laws: is that right hand drive or left hand drive? It may not matter much, but helps clarify "drivers" vs left or right. I checked my US-spec '83 diesel and I only have one door contact on either side. I also checked the wiring diagrams for 230E's and don't see a second door switch, but they're not super-user friendly documents.

I'm speculating here: but is there an aftermarket alarm or immobilizer added? That may be the second door contact.

Two suggestions - if possible, remove and clean the lower door contact. You may want to disconnect the battery first since your wiring may be a bit wacky and you don't know how much current is actually going through the circuit (I'd double-check for the aftermarket alarm, because you may end up really immobilizing your car if you end up disabling that).

Pull fuse 14 and see what happens (I think 14 is the "warning circuit" fuse and that may eliminate the reverse path).

I think you may have a relay that is sticking and creating a reverse current path that keeps the ignition switch energized. That may explain the lights and the shutdown.

Thanks Yak, this sounds like a very strong possibility. Someone on a different forum suggested that the second door switch may be for a feature which allows operation of the electric windows when the drivers door is open and keys removed from ignition. Maybe if the relay for that feeature is faulty then it might be doing exactly what you suggest. I've just been out to try and find this relay, but unfortunately it is raining buckets outside! That's the problem with living in Ireland - this time of year it rains more often than not! If its not raining in the morning I will take a look before I go to work.

The car is a RHD car, and indeed it does have an after-market alarm installed, but I don't think it is sophisticated enough to include a bespoke door switch. I see on the passenger side where there is a single switch there is also a stamping with blanking plate for a second switch in the same position as the lower one on the drivers door. Perhaps European models were equipped with this feature which allows electric window operation when the drivers door is open and the keys out of the ignition? It seems an odd feature though.

I will report back what I find tomorrow. Thanks again for your help and advice.

I didn't dare try to drive the car with the key out, although I was tempted just for the novelty value! Mind you, I guess the steering lock would kick in when I try to make the first turn! The car does rev when the key is out, so I guess it would move if I put it in drive.

Hi all,

I still haven't solved my problem yet! Pressures of work has kept me til late most nights, so I haven't been able to give it the attention I would have liked. Anyway, over the last few days I was able to try a few things out at last, and this is what I found:

1) The lights which are lit on the dash when the key is out of the ignition and engine running, are the same and those which are normally alight when the key is inserted and the ignition switched on to the final point before the starter is engaged. These lights also light up if I just open the door of the car whilst the engine is off.
2) I tried operating the lower door switch manually whilst the engine is off to listen for the relay click, but when I do this those ignition lights on the dash come on with a click and something briefly whirrs (fuel pump?)
3) I tried looking for the relay box in the engine bay in front of the fuse box, but alas it isn't there on my car. I've tried looking elsewhere for the relays, but can't find them. I read on a forum that there is a relay under the centre console gear selector surround, just ahead of the gear lever. I found that and pulled it out, but I still had the same fault.

Does anyone have any suggestions where I might find the relays in my car? There must be another place in my car where the relays are located - any ideas where I might look?

Thank you very much for your continued help and advice.

I have the same problem with the car not turning off - did you get yours fixed?
 

Can you letme know what you did to get your car fixed so it would turn off? My has been running for hours...and I am in Ecuador and noone has been able to figure it out.

Many thanks in advance!

Sadler@ponymail.com

Darryl Sadler

if you cant get it to turn off, block the intake/throttle and get the engine to stall. Running for hours at idle is going to cause a lot of carbon buildup so don't let it do that.