500SEL troubles (little ones)

[plink49]

I am the proud new owner (USA) of an immaculate 1992 500SEL (what a car!) but it has one quirk: The auto locking with the keyfob is erratic...different doors lock/unlock each time and at different receiver areas...any help here? Similar problems with the rear seat headrest up/down with console switch...different headrests react at different times. It's a weird problem

 

[Peter Guenther]

Headrests

The headrests are powered by electric motors, there is a control unit under the drivers side rear seat, that senses when they are up /down. Mine started going out of sequence, so I held the switch down to resequence. I think I stripped the gears a little, I now dont use the dash switch but can control each from the door. The control module is looking for a little stall current, due to slippage it keeps on powering. My friends at MB have told me it is not a big job removing the seatback if you know where all the fasteners are, I have decided to ignore it for the time being.
The lock and unlock is a puzzle, the sensors in the door and trunk (boot) start the pump just as the key would, what happens when you use the lock button on the drivers door, and do you have any other items not behaving? The lumbar, backup, and some other items are controlled by the same pump

 

[NormanB]

Plink

Is this any use to you:

http://interior.mbzarticles.org/pwrhdrests/ ?

Good luck

 

[plink49]

Thanks Peter & Norman! That MB site is great....if nothing more than the leather restoration site/products! As far as the door locking I've determined that some of the lock buttons (the drivers door in particular) are "sticky" and will depress or go up if "urged to". By the way, where in the car is the pump located for said devices?

 

[Peter Guenther]

Lock/Unlock

Plink
The locking / unlocking, vacum headrests, fuel door, lumbar, HVAC support, trunk (boot) retracting handle, and backup rods, are all controlled by the pump under the passenger rear seat in a foam container. You must be careful when pulling the seat if you have the seat heaters. This of course depends on the model and equipent, if you have the electrically adjustable rear seat you will have electric headrests.

 

[monmoulds7]

vac pump

Plink,
I had a problem with my vac pump in that it didn'e work on my 1992SEL 600. I got to the pump under the seat and took the back off the assembly to reveal the pump, motor and circuit board. I took the motor out and then dismantled the pump from the top of the motor to find the pump vanes and housing had broken up. Out of curiosity it superglued it back together and with a bit of fiddling got it to work but it shows the same symptoms now as you have. This leads me to believe that a new pump is needed and now I have to source one without buying the whole unit. Anyone got any ideas.
Dave.

 

[Peter Guenther]

Vacum Pump

There is at least one source for rebuilts in the US. (George_Murphy@compuserve.com)
otherwisw you will have to buy new. There were some on E-Bay from a parts distributor in Miami. If it does not work or is incompatible that can be a problem.