Engine keeps running with ignition key out

[CharlesJones]

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!
• Looking in the drivers door jamb I see there are 2 switches which are activated by closing the door. If I manually operate these whilst keeping the door open, I can see that the upper switch turns off the "you left the lights on" warning buzzer and the courtesy light. I don't know what function the lower switch normally performs, but it is this lower switch which causes the engine to shutdown in the case of my electrical fault. With the engine still running, key out of ignition, I can open the door, press in this switch in the door jamb, and the engine shuts straight 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

 

[BlackC55]

I would be looking at a possible short circuit on the loom for that door switch. Very odd fault though!

 

[cammy]

Maybe a broken wire.
Had a similar problem with my clk a few months back and it was a broken wire through the boot lid hinge.

 

[fitzcarraldo]

if your car has electric windows:
Were you able (before you experienced the problem) to operate the electric windows when you had already pulled out the ign/key and when the drivers door was open ? If you don't have electric windows ignore the above - but if you have them and you can do the above the you should first look at the convenience by-pass relay which enables windows operation with the key out and driver's door open. You'll find it in the box in front of the fuse box. Press the release lever on the side and pull off the cover. Look for a relay that is warm or hot (it's only warm or hot after you have left the driver's door open for a while) pull out the relay and see if the symptoms have gone. Before you do that, check with the engine shut down and the driver's door open whether you can hear a clicking noise when you press the 2nd. door contact switch (not the one that operates the dome light - but the other one) If you can hear the click then chase the relay in case it is not fitted in the relay box in the engine bay but perhaps behind the plastic panel next to the driver's foot (I assume its a RHD car ?) If you don't hear a clicking noise then there is already a problem (if you have convenience operation of windows) and the
relay may have a faulty relay. What confuses me here is that the engine shuts off when you close the door while it won't shut off when you turn off the key before you open the door. Post back your findings. Not sure if your car has already a convienience anti-feed back diode ? Let us know the exact built date (Month+year). Then I can dig up the wiring diagram at the saltmine. I'm sure it has to do with the electric windows by-pass relay - providing it has elect/windows.
Also, can someone let me know how to get email notification when a reply was posted ?

Good luck,

fitzcarraldo

 

[MOCAŠ]

Also, can someone let me know how to get email notification when a reply was posted ?

Click on the "Thread tools" option at the top-right of the thread, and select "Subscribe to this thread."

 

[CharlesJones]

Thank you all very much for your replies - they're all very helpful. I had been thinking I might have a faulty ignition switch, but having read your suggestions it looks like I need to look more towards the wiring surrounding that door switch.

Fitzcarraldo, thank you so much for your response - your suggestions really sound like they might very well explain the problem. I didn't even know such a feature existed which allowed operation of the electric windows with ignition off whilst the drivers door was open, and if my car is indeed equipped with this feature then it makes the connection between the ignition switch and that door contact. Perhaps if the relay is faulty it is leaving the ignition switch live somehow?

Yes, the car is indeed RHD, and is a 1982 230E saloon (model 123 223). Looking at the paper work with the car I can't see anywhere it mentions the month of manufacture, although I do have the chassis/engine/options numbers etc, if you think that might help at all.

As regards operating the electric windows before this problem occurred, I can remember they wouldn't operate with the keys out of the ignition, but I don't think I ever tried it with the drivers door open, so I can't say for certain whether the car had that feature or not. I can't think of anything else which that second switch could be for though.

When I read your post this evening I excitedly went outside to try and see if I could hear the relay clicking when I operate this switch, but unfortunately it is tipping down with rain outside! That's the problem with living in Ireland - its just always raining! If it stops by morning I will try before I leave for work and report back. Thanks again for your help and advice.

 

[CharlesJones]

Fitzcarraldo, I've just been and had a look in the little glove box owner's manual which came with the car when new, and it mentions the feature where the electric windows will open with the keys out of the ignition and the driver's door open, but it says "not with RHD vehicles". I can't understand what that second door contact is for if it is not this feature though. Perhaps the owner's manual is incorrect for this particular model - they may have changed the model spec but not the manual, which doesn't seem unlikely. Or do you know if any of these models had a warning buzzer indicating that the keys are left in the ignition when the drivers door opens?

 

[CharlesJones]

Hi,

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 like Fitzcarraldo suggested, 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 relay which Fitzcarraldo describes? 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.