C124 300ce Central locking question.

whirsk

Active Member
Joined
Nov 30, 2014
Messages
75
Location
Galway Ireland
Car
1990 300ce
Hi Folks
I am currently having an issue with central locking on coupe.
The passenger door will open and activate central locking (drivers,fuel,boot).
Unfortunately the drivers door will not activate central locking.
Is this a completely mechanical/vacuum or is there an electronc controller?
Perhaps there is a damaged switch/contact in drivers door?
If anyone has had any experience with these systems,advice greatly appreciated.
Thanks in advance.

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CabrioDave

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Dec 18, 2016
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243
Location
West Midlands, UK
Car
A124 E220 Cabriolet
An electrical system tells the electronic controller that a doorlock has been opened/closed (or the remote system activated). That controller then gets the electrical pump to "suck" or "blow", as it were, to move all the lock actuators.

If the passenger door does it OK, it looks like the controller and pump are fine. For some (electrical?) reason, the message is not reaching the controller from the driver's door lock.

Does the boot lock activate things?
 
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whirsk

whirsk

Active Member
Joined
Nov 30, 2014
Messages
75
Location
Galway Ireland
Car
1990 300ce
Thanks CabrioDave
Not sure about the boot,will check it out.

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Pontoneer

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Aug 19, 2002
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Central Scotland
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'99 S320 W140
There's a microswitch in each lock so that when you turn the key one way or the other it makes the pump run accordingly to operate the actuators .
 

Dec

MB Enthusiast
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Jul 28, 2004
Messages
4,475
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C180,A.
Can you still lock or unlock the driver’s door with the turn of the key, without the assistance of the central locking?

Dec
 
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whirsk

whirsk

Active Member
Joined
Nov 30, 2014
Messages
75
Location
Galway Ireland
Car
1990 300ce
Hi Folks
The story so far appears that the drivers door and boot will open manually,but neither are activating the central locking.
I can hear the microswitches clicking in both locks.
Where is the locking control unit located perhaps i have damaged wiring?
Thanks in advance

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Dec

MB Enthusiast
Joined
Jul 28, 2004
Messages
4,475
Car
C180,A.
Under back seat I think. Sit inside the car and lock the passenger door and you will hear the pump run for about 2 seconds.

See… PeachPartsWiki: Keyless Entry Install

How many Yellow tubes are there on your vacuum pump?

Dec
 

CabrioDave

Active Member
Joined
Dec 18, 2016
Messages
243
Location
West Midlands, UK
Car
A124 E220 Cabriolet
There are quite a few older threads about this. (I know, because they recently helped me sort out my central locking.)
The controller is in different places for different models. My cabriolet: under the rear seat, at driver's side of the car, together with the vacuum pump. Can't remember whether the coupé is the same.
 
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whirsk

whirsk

Active Member
Joined
Nov 30, 2014
Messages
75
Location
Galway Ireland
Car
1990 300ce
Thanks Guys
Will check it out and report back.
Cheers for info,safey driving.

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