[W126 Coupe] Vacuum Seat Locking

[Dick Spellman]

Hi Yousef,

One of those pin switches (I do not know which one) is responsible for 
determining the open or closed state of the door and this determines the 
state of the seat back locks.  Doors closed, seat backs locked.  Any 
door open, both seats in unlocked state.   You can depress the pin 
switch retainers to either end of a switch to pull from the door frame 
and check the function with a vohm meter after removing one leg on the 
switch leads.   I did replace one some 10 years back to resolve the 
issue you have.  The electrical circuit powers a solenoid that 
interrupts vacuum to the door locks.  So, the vacuum line under the 
seats goes to this solenoid and then from solenoid to engine vacuum and 
vacuum reservoir under the fender.

Regards,
Dick

On 11/14/2011 12:02 AM, Yousef wrote:

> Thanks Dick

>

> Regarding the 3rd point. Do you mean one of the three black switches 

>  mounted bear the door hinges? i know one is for the light and one is 

> for the seatbelt presenter could it be the third is for seat locking?

>

> Yousef

> Sent from my iPhone

>

> On Nov 14, 2011, at 3:20 AM, Dick Spellman <dick.spellman at gmail.com 

> <mailto:dick.spellman at gmail.com>> wrote:

>

>> Hi Yousef,

>>

>> So, it is one of the following:

>>

>>  1. Bad fuse that provides power to the seat back locking valve (I'm

>>     not certain as to which fuse this is but, you can check the

>>     mbcoupes website for fuse chart relating to your model year)

>>  2. Bad seat back locking valve (found mounted to steering column

>>     behind knee bolster) (identified where it has both vacuum lines

>>     and electric leads attached)

>>  3. Bad door pin switch preventing the seat back locking valve from

>>     knowing the doors are closed.

>>

>> Good luck,

>> Dick

>>

>> On 11/13/2011 4:11 PM, Yousef wrote:

>>> Hey All

>>>

>>> ive seen this post a while ago and kept it in mind till i remove my 

>>> seats .. And now i have .. And after reading it again and again ive 

>>> notice that i havent understood much :P..so here is what i 

>>> understand from my situaion..

>>>

>>> I can see the locking mechansim and i see the vaccum lines .. Now i 

>>> do not have mityvac (not availabe in Dubai and ordering online is 

>>> cazy expensive) .. So i had to.. Use.. My....... mouth :S.. (you can 

>>> make fun all you want but it had to be done  hahaha ).. Now 

>>> introducing vaccum does latch the lock and the tubes seem to hold 

>>> the vaccum with no leaks .. Pressing the button releases the latch.. 

>>> It seems normal to me ..

>>>

>>> So could it be that the engine is generating enough vaccum? Other 

>>> systems that work on vaccum (vac pods central lock ) work fine .. 

>>> Mechanically the car runs really well.. Only comment would be that 

>>> kickdown doesnt work (but thats a totally different story)

>>>

>>> Oh and i hav this problem with both seats

>>>

>>> I have noticed that the vaccum line meet some where in the seat but 

>>> couldnt tell properly ..

>>>

>>> Finally what do you people say do i buy the MB slip paste to 

>>> lubricate the seat rails & gears or just go with normal grease?

>>>

>>> Cheers

>>> Yousef

>>>

>>>

>>>

>>> Sent from my iPhone

>>>

>>> On Sep 15, 2011, at 5:26 PM, "L&D gardner" <cruftsk9 at tpg.com.au 

>>> <mailto:cruftsk9 at tpg.com.au>> wrote:

>>>

>>>> Hi Folks

>>>> Thought I would share my experiences with this problem,first off 

>>>> many thanks to all the people who freely gave advise.

>>>> The seat rail caps,which in my car proved extremely difficult to 

>>>> remove without damage can be removed with a pair of thin steel 

>>>> blades which I fabricated with a 10 degree bend 1/4" from the end.I 

>>>> used a Mityvac on the line

>>>> from the seat lock and found I needed a minimum of at least 22HG of 

>>>> vacuum before the seat would lock.

>>>> For the springs holding  the front material cover I used an old 

>>>> bicycle wheel spoke and bent the threaded end into a loop for 

>>>> gripping in the hand while the  hooked end slid under the seat 

>>>> ,which located the small end of the spring perfectly.Also the fact 

>>>> that the car had tailor made fitted sheepskins didn't exactly help 

>>>> the repair process either, I could have removed them but refitting 

>>>> them would have been a pain too.

>>>> On the subject of "Old list members" I have been subscribing  for 

>>>> roughly 10 years  and while I would have liked to contribute more, 

>>>> lack of knowledge and expertise with these cars prevents me from 

>>>> doing so,but  I find I am learning new things from the list every 

>>>> day,in fact owning one of these cars without the list for someone 

>>>> like me in a fairly remote location would be a scary proposition.

>>>>                                                                                                                    

>>>> Kind Regards Dan Gardner  1986 560 SEC  Euro (220kw)


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