SL/R129: central locking fault
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From: Manchester, UK
500 SL R129, Blue - 1991. Mini Cooper S, Works Kit Silver - 2007. Mitsubishi FTO, Silver - 1996.
central locking fault
Hello my 500sl 1991 is not responding when i point key at it to activate the central locking. If i use the key in the lock i can open one lock at a time, but not the whole car at the same time. The lights flash on the door handles when I turn the key, but the locks will only open manually. All the fuses look as though they are intact. Any idea's anyone? ALSO my aerial is not extending fully as the car has been standing for a while. Any ideas for that one?
Thanks very much everyone.
Thanks very much everyone.
Thread Starter
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Joined: Jul 2005
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From: Manchester, UK
500 SL R129, Blue - 1991. Mini Cooper S, Works Kit Silver - 2007. Mitsubishi FTO, Silver - 1996.
the remote does activate the lights in the door, but the locks don't turn, so i think the key is fine. I was fiddling about with it last night, and the motors are trying to turn but nothing happens, and worse... the motors are gently humming away if i leave the car after having used the remote. If I manually deadlock the doors and trunk the whirring stops after a few goes. Maybe the motors need some oil? The car was standing for 12 months and the battery had died... maybe the alarm will need to be reset or something... urghhh starting sound £££$$$$££££$$$$....
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From: Massachusetts
2018 GLE350, 2014 G550, 2000 SL500, 1980 TR8, 1995 E320 Cabriolet
b4mmy -
In an MB the lock actuators are vacuum servos, not electric actuators like most other cars. The SL (at least the later years) uses a complicated (remember, no system is too complicated for a German car) system of pneumatics driven by an electric vaccum pump/controller unit located in the boot (next to the battery) to lock/unlock things. The sound you hear when you press the key is the pump running. The system gets electrical feedback from the locks to determine whether actuation has occured. If the controller doesn't get the correct signals, the pump will continue to run for a while after being triggered by something like the key. The locks operate in a fixed sequence (first doors, then compartments, then the boot, I think, but don't quote me) which I believe is because the vacuum pump can't supply the necessary vacuum to all actuators simultaneously.
The symptoms you describe sound most like a vacuum leak in one of the lines or one of the actuators. If you locate the controller you will see a series of yellow and white hard plastic tubes running around the car. Follow them and look for a connection that has come off or a line that has been damaged. Watch and listen (for air leaks) at each actuator.
Failing a leak, it could be the controller/pump unit.
I hope this helps.
- FD
In an MB the lock actuators are vacuum servos, not electric actuators like most other cars. The SL (at least the later years) uses a complicated (remember, no system is too complicated for a German car) system of pneumatics driven by an electric vaccum pump/controller unit located in the boot (next to the battery) to lock/unlock things. The sound you hear when you press the key is the pump running. The system gets electrical feedback from the locks to determine whether actuation has occured. If the controller doesn't get the correct signals, the pump will continue to run for a while after being triggered by something like the key. The locks operate in a fixed sequence (first doors, then compartments, then the boot, I think, but don't quote me) which I believe is because the vacuum pump can't supply the necessary vacuum to all actuators simultaneously.
The symptoms you describe sound most like a vacuum leak in one of the lines or one of the actuators. If you locate the controller you will see a series of yellow and white hard plastic tubes running around the car. Follow them and look for a connection that has come off or a line that has been damaged. Watch and listen (for air leaks) at each actuator.
Failing a leak, it could be the controller/pump unit.
I hope this helps.
- FD
Thread Starter
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From: Manchester, UK
500 SL R129, Blue - 1991. Mini Cooper S, Works Kit Silver - 2007. Mitsubishi FTO, Silver - 1996.
...thank you Floobydust, that's very helpful. Sunday tomorrow so I'll have a look... the noise was definitely coming from the back and I'm sure I'll be able to work it out with your help.
I've another problem
which I am just about to post...
I've another problem
which I am just about to post...
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From: So. Cal.
SL500 2001 Formula 1 Edition;
Speaking of which . . . I have a trunk problem. The locking system will unlock the trunk, BUT, the dash button does not pop the trunk open, nor does it seem to unlock the trunk (although the indicator light works when it is opened). Also, the key button will unlock the trunk, but not pop it open. One must push the button on the trunk to open it.
This is the way it was working when I got the car (pre-owned) Is this functioning correctly? Or is something wrong? Oh, BTW, 2001 SL500.
Also, original post mentioned an antenna problem. New antenna costs about $250. Has anyone tried replacing theirs with a universal antenna that can be had from Auto Zone or similar for only $69? I guess two questions:
Will it fit and not look like aftermarket?
Will it work?
This is the way it was working when I got the car (pre-owned) Is this functioning correctly? Or is something wrong? Oh, BTW, 2001 SL500.
Also, original post mentioned an antenna problem. New antenna costs about $250. Has anyone tried replacing theirs with a universal antenna that can be had from Auto Zone or similar for only $69? I guess two questions:
Will it fit and not look like aftermarket?
Will it work?
Last edited by mebeJOE; Aug 29, 2005 at 01:03 PM.
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Thread Starter
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From: Manchester, UK
500 SL R129, Blue - 1991. Mini Cooper S, Works Kit Silver - 2007. Mitsubishi FTO, Silver - 1996.
Hi again!
I was looking for this central locking fault yesterday and next to the controller unit (near the battery) there is a red push button that you can push in and out.... and another one with no red button next to it.... does anyone know what that is? Is it a manual reset for something, or does it recharge the pump. I know I really shouldn't have, but I couldn't help pushing it in and out a few times to see what happened, and er.... nothing did! Thank goodness. For all I know I might have recalibrated the car and turned it into a Volkswagen, and the Merc dealer would be rubbing his hands with glee that I have innocently racked up another few grand in repair bills.... which would be just great! So, has anyone any idea what that little red button is? And no, the passenger seat didn't eject.
Chris
I was looking for this central locking fault yesterday and next to the controller unit (near the battery) there is a red push button that you can push in and out.... and another one with no red button next to it.... does anyone know what that is? Is it a manual reset for something, or does it recharge the pump. I know I really shouldn't have, but I couldn't help pushing it in and out a few times to see what happened, and er.... nothing did! Thank goodness. For all I know I might have recalibrated the car and turned it into a Volkswagen, and the Merc dealer would be rubbing his hands with glee that I have innocently racked up another few grand in repair bills.... which would be just great! So, has anyone any idea what that little red button is? And no, the passenger seat didn't eject.
Chris
Originally Posted by Floobydust
b4mmy -
The symptoms you describe sound most like a vacuum leak in one of the lines or one of the actuators. If you locate the controller you will see a series of yellow and white hard plastic tubes running around the car. Follow them and look for a connection that has come off or a line that has been damaged. Watch and listen (for air leaks) at each actuator.
- FD
The symptoms you describe sound most like a vacuum leak in one of the lines or one of the actuators. If you locate the controller you will see a series of yellow and white hard plastic tubes running around the car. Follow them and look for a connection that has come off or a line that has been damaged. Watch and listen (for air leaks) at each actuator.
- FD
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From: Taiwan
300SL-24 1992 White
The red button & Vacuum Pump
Hi b4mmy,
The red button is for fuel door unlock.
I agree with FD. your symptoms would be: A. vacuum leak in one of the lines or one of the actuators or, B.the vacuum servo disorder. In A case, you would propably still can lock/unlock the doors, but in B case, no chance. The remote central locking system can still work because it is a electrical control.
The lucky thing is, the vacuum pump(servo) can be fixed, but need to find the technician.
Morris Wu
The red button is for fuel door unlock.
I agree with FD. your symptoms would be: A. vacuum leak in one of the lines or one of the actuators or, B.the vacuum servo disorder. In A case, you would propably still can lock/unlock the doors, but in B case, no chance. The remote central locking system can still work because it is a electrical control.
The lucky thing is, the vacuum pump(servo) can be fixed, but need to find the technician.
Morris Wu
Last edited by MorrisWu; Sep 12, 2005 at 08:47 PM.
Thread Starter
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Joined: Jul 2005
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From: Manchester, UK
500 SL R129, Blue - 1991. Mini Cooper S, Works Kit Silver - 2007. Mitsubishi FTO, Silver - 1996.
Thanks Morris. By the way, I explained how to post picture on your 300 - 500 post! Hope it helps.
Thread Starter
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Joined: Jul 2005
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From: Manchester, UK
500 SL R129, Blue - 1991. Mini Cooper S, Works Kit Silver - 2007. Mitsubishi FTO, Silver - 1996.
Originally Posted by MJM
Hello,
Did you get anywhere with searching for your locking problem? I have exactly the same problem with my SL and am trying to figure out where to go next.
Thanks,
Matthew
Did you get anywhere with searching for your locking problem? I have exactly the same problem with my SL and am trying to figure out where to go next.
Thanks,
Matthew
Almost a Member!
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From: Taiwan
300SL-24 1992 White
Hi b4mmy,
I suggest you have the car examined the vacuum system for any drop-off connector(cause leakage)at first by the dealship specialist, the expense would be less.
If it is sure the pump problem, then to find the replacement.
I suggest you have the car examined the vacuum system for any drop-off connector(cause leakage)at first by the dealship specialist, the expense would be less.
If it is sure the pump problem, then to find the replacement.
Thread Starter
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Joined: Jul 2005
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From: Manchester, UK
500 SL R129, Blue - 1991. Mini Cooper S, Works Kit Silver - 2007. Mitsubishi FTO, Silver - 1996.
Originally Posted by TheV12pwr
I've got the pump for $185.00 shipped!!!
Let me know...
Let me know...
Chris
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Thread Starter
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Joined: Jul 2005
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From: Manchester, UK
500 SL R129, Blue - 1991. Mini Cooper S, Works Kit Silver - 2007. Mitsubishi FTO, Silver - 1996.
Originally Posted by BANANA
Thread Starter
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From: Manchester, UK
500 SL R129, Blue - 1991. Mini Cooper S, Works Kit Silver - 2007. Mitsubishi FTO, Silver - 1996.
Originally Posted by TheV12pwr
I've got the pump for $185.00 shipped!!!
Let me know...
Let me know...
Newbie
Joined: Apr 2004
Posts: 9
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From: Hampshire, England
500SL '93
the pump is making lots of noise trying to lock my driver's door, but with no success.
i've decided to take out fuse no. 6 and make do with locking the two doors and boot manually.
all of the internal cubby holes and pockets can just stay permanently unlocked for the meantime.
i hope this doesn't mess with any internal diagnostics ?
i've decided to take out fuse no. 6 and make do with locking the two doors and boot manually.
all of the internal cubby holes and pockets can just stay permanently unlocked for the meantime.
i hope this doesn't mess with any internal diagnostics ?
Newbie
Joined: Dec 2011
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Brainstorm needed!
I've been fighting with this interior locking s#*t for a week now (in my spare time) and I have installed a new pump, checked lines for leaks, tried every remote and manual key unlocking and locking combination at both doors with dash key set at #2 position... I'm at a dead end. The storage boxes, center console and door pockets will not unlock, yet the pump is correctly locking and unlocking doors, trunk and fuel door with no signs of any leaks. Fuse is good. Any ideas?!! 
HELP
1992 500SL
HELP
1992 500SL
Newbie
Joined: May 2012
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R129
I have a very interesting problem. If I open the passenger's door and leave it open for several minutes, then close the door, the entire car will lock. It happens very frequently. I hope some can point me in the right direction.
Thank You,
Arthur
Thank You,
Arthur
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From: Eastern Kansas
94 SL 600, 98 993, 89 XJS Conv., 85 Daimlier Princess 16 Hybrid Lincoln 16 Chevy crewcab
Don't know about your SEL model. (had an Se L in the 70's excellent 350 power plant, but that's another story )
The lock on my 94 SL has a mechanical aspect, and that is working for you.
The Infra red key fob activates a vacuum pump that drives a negative pressure system throughout the vehicle. door locks, trunk, interior compartments. The fob needs a receptor ( small red/green light pad below the door handle, trunk button ) and if that system is working the red or green light will flash.
If that responds, then the pump for the vacuum, which makes a soft sound from the gas filler area in trunk would be the next site to examine.
Each area has its own vacuum line ( hard plastic tube that is yellow with green in the center console and door ) that fits about 1/2" into a thicker, softer rubber tube attached to the valve system. If the door panel has been removed the tube may not be reconnected!
Weak battery is always a problem for MB's ;(
Good luck with the run down.
The lock on my 94 SL has a mechanical aspect, and that is working for you.
The Infra red key fob activates a vacuum pump that drives a negative pressure system throughout the vehicle. door locks, trunk, interior compartments. The fob needs a receptor ( small red/green light pad below the door handle, trunk button ) and if that system is working the red or green light will flash.
If that responds, then the pump for the vacuum, which makes a soft sound from the gas filler area in trunk would be the next site to examine.
Each area has its own vacuum line ( hard plastic tube that is yellow with green in the center console and door ) that fits about 1/2" into a thicker, softer rubber tube attached to the valve system. If the door panel has been removed the tube may not be reconnected!
Weak battery is always a problem for MB's ;(
Good luck with the run down.
Newbie
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1991 500sl
500sl nightmares.
Hello I am the unfortunate owner of 1991 500sl. I am having issues with the remote lock it only works in dark areas or at night. That is due to old age, i can not lock or unlock the driver's door. I can only look it using the trunk option. My quetion would be, if i install an after market system will it work. i found one on ebay and they swore it will work. What do you think? also my roll bar stays up no i can't lower it. I also have a gap at the back of the hard top. the gap is like less than an inch , so the back of the hard top is not fully flushed with the body. Can anyone help with these questions , I really need all the help, and thank you in advance.
Member
Joined: Aug 2010
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1990 500sl
Hello I am the unfortunate owner of 1991 500sl. I am having issues with the remote lock it only works in dark areas or at night. That is due to old age, i can not lock or unlock the driver's door. I can only look it using the trunk option. My quetion would be, if i install an after market system will it work. i found one on ebay and they swore it will work. What do you think? also my roll bar stays up no i can't lower it. I also have a gap at the back of the hard top. the gap is like less than an inch , so the back of the hard top is not fully flushed with the body. Can anyone help with these questions , I really need all the help, and thank you in advance.
As for the hardtop not latching all the way it sounds like you have some hydraulic issues. Does your soft top go up and down properly?
Take care,
George
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2008 E 350
Have 2008 E 350, I see where our trunk release problem is not unique, now central light problem and license lamps not working... when we use the key faub to open and it doesn't, we pulled the manual latch release on the trunk and there is a little whirring sound coming from what seems like the trunk... just hear it for a minute... does this give us clue as to the problem... we will be checking the wiring... but I just wonder what that whirring sound is... and could that point us to the problem?
