W210 Central locking intermittant fault

mtinlin

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The central locking on my 1995 E230 fails to operate when I first use the car each morning. I have to use the key in the passenger door to get into the vehicle. It starts normally with the key and then operates normally until the next morning. The alarm/imobiliser has always been a bit of a pain but generally works. Any ideas where I should start on this one? There does not seem to be anything else amiss with the key. The batteries are quite new and I have reset the system by disconnecting the car's battery. The green light in the door handle does not work but it's been like that for years.
On a related note - can I buy a repair manual for this car?
 
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mtinlin

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That would be a good start. Given that it is connected to the alarm system I would guess at that being the most likely cause of the problem. I notice that when I open the door manually the other door locks do not operate. Any idea where the pump is so that I can clean the connectors?
 
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mtinlin

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Thanks to Television I found the central locking pump under the rear seat. Nothing to observe really with all the connections clean and tidy. I disconnected the battery to reset the alarm system (again) but this time when I restarted the car the indicators and wiper have come out in sympathy with the central locking. And I thought secondary industrial action was illegal! I ran the car for a few minutes after which time everything started working normally again. Can anyone think of a connection between the central locking, indicators and wiper?
 

television

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To start with I would get some non drying switch cleaner and spray all of the fuses and holders
 
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mtinlin

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I don't know whether this is related to my problem but I would like to eliminate it from my enquiries. Hopefully I have attached a picture of the courtesy light fixture that sits behind the rear view mirror. the black object in the top right of the picture which seems to be some kind of sensor is buzzing. Any idea what this is? Is it connected to the alarm/imobiliser?
I now seem to have a permanent loss of power to windows, central locking, indicators, wiper (but not washer pump) and interior light. Anyone think of a connection here?
Thanks, Malcolm.
 

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television

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That is the sensor and motor for the air con I believe, and not part of the locking,,it should not run all of the time
 
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mtinlin

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Woe is me

Having got nowhere trying to solve the lack of windows, central locking, indicators etc myself, I booked the car into a local auto electrician (local specialist could not look at the car for another week). The auto electrican quickly gave up and gave me another garage to contact. He seemed to think that there might be a fault in the area of the ECU. Does this sound likely? Anyone out there with a similar experience?
 

Dec

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How did you go about disconecting the battery, did you remove one terminal, Positive or Negitave?

You might have blowen something if the reconection wasent quick, without sparks.

Dec
 

television

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Sadly the word ECU refers to all and nothing, the odd thing is here that the windows are nothing to do with the locking
 

television

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I can send him all of the details on that
 

Alex Crow

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That is the sensor and motor for the air con I believe, and not part of the locking,,it should not run all of the time

they do run all the time but should be silent, buzzing is annoying but not related to you other problems.
 
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mtinlin

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Thanks for your thoughts. I did disconnect the negative terminal on the battery a couple of times in an effort to clear the fault. On both occasions it appeared to have no impact either way. The overall problem of loss of windows, central locking, indicators etc etc has developed over a period of time. At the beginning, the fault would clear almost straight away once the car started whereas now it fails to correct itself at all. In other words, the fault seemed to develop over time rather than after a single event.
It did occur to me that that there is an automatic opening and closing of the windows associated with the central locking / alarm system. It was this link that made me think that the fault might be with the alarm/immobiliser.
Can you send me the details on comfort control please? Could that unit be positioned under the bonnet next to the ECU?
Thanks.
 

Dec

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We don’t have the same car but we share the same year so I though you may have a similar comfort control unit, in my case it is in the boot, hidden to the side of the battery, in your case you may have something similar, possibly under back seat or inside, possibly the drivers door.

Something somewhere has been blown or of a poor conection, maybe a fuse or comfort control relay.

Dec
 

television

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I think at this stage I would remove all of the fuse and control units and spray the contacts with a good none drying switch cleaner, both the pins and the socket pins. the other thing is a missing or poor earth strap somewhere
 
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mtinlin

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I did check as many connections and earth points as I could and found no corrosion or dirt etc although I have not tried any cleaner. I'm not sure what you mean by non-drying Television? Do you have a brand name? The more I think about this the more I think it links to the remote opening. Normally, I would press the single button on the remote/key, the indicators would flash, the central locking would open and the interior light come on (I think). The light on the interior mirror would flash green. Apart from the windscreen wipers (and assuming the sunroof is on the same circuit as the windows) these are the circuits that are not now working except for the lights on the mirror. Is this what is called the 'Comfort' system or is this more the remote/alarm? If I could reduce down to these areas I could concentrate on checking and cleaning them. At the moment I am looking at the entire loom and there is quite a bit of it!
Thanks.
 

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