b4mmy

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.

mebeJOE

Could the key problem just be a battery in the key housing?

My antenna does not extend at all. The motor is bad. Maybe yours is the same?

b4mmy

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 £££$$$$££££$$$$....

Floobydust

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

b4mmy

...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...

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

mebeJOE

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?

b4mmy

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

MorrisWu

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

b4mmy

Thanks Morris. By the way, I explained how to post picture on your 300 - 500 post! Hope it helps.

b4mmy

Got around to looking at this and my garage say it's the pump itself. It is running, but is not creating any pressure. Does anyone know where I can get one (oem or otherswise) that isn't going to create an even bigger hole in my shrinking pockets?

TheV12pwr

I've got the pump for $185.00 shipped!!!
Let me know...

MorrisWu

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.

b4mmy

Hi V12pwr I am just having my garage check the pic out... do you have the part number on your pump please? If it's right for my 129 500 (1991) then I'm sure I'll take it. Thank you for the offer.
Chris

BANANA

http://www.benzworld.org/forums/foru...posts=8&fid=25

b4mmy

Interesting! I'll see if I can strip it down over the weekend. I don't suppose you can blame the mechanic for not doing this, I guess the labour charge would be the same for them, and you get a new unit. But I'd rather save the cash any day! Thanks Banana.

b4mmy

Got the pump V12, arrived today. Thank you.

sebastianforbes

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 ?

500SLZ

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

art1saf

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

skcontrol6

I have 1992 600 sel benz, Cannot open the door with remote control . I have to do it with the key. The same go for the trunk. I do not drive it much. I store all winter. Any ideas guys.
Thanks

SRHsl600

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.

bybloss

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.

dirtyguido

As far as the remote locking only working during dark. - Replace the batteries in the key. There are 4 357 batteries in that key, you can usually find them at a pharmacy where they keep the hearing aid batteries.

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

susanluk

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?