w124 coupe front seats

[LNM]

Magnet man again.

The release mechanisms on both front seats on my coupe are broken. This means the seats don't lock upright anymore + if I go to an over-zealous MOT man, it will fail.

I suspect the seats will have to come out, at least the back'll have to come off at any rate.

Has anyone ever attempted this on these seats? I can feel a 4, maybe 5 spannerer coming on..... seeing as how the Haynes manual doesn't even mention the innards of the seat.

Someone tell me I havent made a mistake getting this thing....

 

[marky]

Hi,
I have an '88 300ce, the seat backs are unlocked when the car is swithched off and they lock when I start up the motor, then I have to press a little button on the side of the seat to unlock (if the key is in the ignition).

Hope that helps

Marky

 

[justin1820]

the seat back rest is vacuum opperated, it will lock in place when the engine is running and will only pull forward when the button is pressed, so the test is have the window open and the engine running with the door shut and you should not be able to pull the seat forward, being as its vacuum opperated if there are any leaks on any circuits eg headlamp level control, rear head rest releases it will not work.

 

[LNM]

WAHEY - IT WORKS !!! Pints all round if I knew who you were.

god-damn, I love this place. I suppose I'd better spend a bit of time reading the manual hadn't I...?

 

[Nik_Codling]

Mine's broken too....

Hi All,

My seat backs don't lock either - I did a search of posts and came up with this one.

So what do I need to check??

All hints and tips greatfully received.

cheers,

Nik

 

[paulcallender]

You need to check the vacuum pipes which go to the vacuum solenoid on the base of the seat; and this solenoid itself. Mine had completely perished rubber bellows, so the only option was to purchase and fit new ones (not a difficult job). They are expensive from the dealer, though, so I'd suggest going to a scrappy or something.

If you are not achieving any vacuum at the pipes with the engine running (door closed, remember) then its time to check all the connections and pipes and the pipe to the manifold itself.

By the way, the Haynes manual is useless in this respect, it seems to not mention anything about any vacuum-operated stuff! If you need it, I have a 'vacuum wiring diagram' of the system, as it relates to a W114, but it looks like they never changed anything between the models.

 

[Nik_Codling]

Hi Paul,

Thanks for your post - looks like that could be the cause then. I'll have to take one of the solenoids out and check it out. Do you know if it's possible to dismantle them, to check whether the bellows are perished?

The pipework looks ok actually - I hope so - checking that could be a pain...

Leading from the solenoid under the driver's seat the blue vacuum pipe runs in to a rubber pipe which then runs under the carpet - where does this lead to? At least if I can check that I can eliminate it.

cheers,

Nik

 

[paulcallender]

For each side, there is a vacuum pipe which splits of using rubber T pieces, to the the door opening switch (it is a combined vacuum and electrical switch), the seat, and the button that can be pressed by the rear seat passenger.

It should be easy to visually check if the bellows are perished - once you have the seat out the car! Failing that, simply blowing through the tube will soon give you an indication. If its the same as my car, there is a double solenoid because there is a rod each side which goes on to a mechanism to 'hook' the seat back secure.

When I first got the car, I wondered why they fitted the rear seat switches, after all, why would you leave the engine running, with nobody sitting in the front seats, but a couple of people in the back seats, with the doors closed........oh, yeah, I got it now

 

[Nik_Codling]

Sounds like a pain in the backside.... Thanks for the info though Paul - at least I know the size of the problem.

I'm going to investigate the possibilities of mechanically fixing the seats upright for the purposes of the MoT. The car just isn't worth spending lots on new solenoids.

Do you really have to take the seats out to access the solenoids??

cheers,

Nik

 

[paulcallender]

Sounds like a pain in the backside.... Thanks for the info though Paul - at least I know the size of the problem.

I'm going to investigate the possibilities of mechanically fixing the seats upright for the purposes of the MoT. The car just isn't worth spending lots on new solenoids.

Do you really have to take the seats out to access the solenoids??

cheers,

Nik

I don't know what else you have in your seat (heater? electric adjustment?) but its not complicated to take the seat out - 4 bolts or something like that, then disconnect the vacuum pipe. I am pretty sure its the only way to get sensible access to the solenoid. And I bet it will be this component which is playing up. Even if you mechanically fix it in place, you'd have to remove the seat to do that.

 

[Nik_Codling]

Thanks to everyone for their help and advice - the seats are now sorted (kind of) - they both lock in place, and both will tip forward if you press both buttons at the same time, or the passenger side works ok on it's own.

Anyway, good enough for me - passed it's MoT so that's another year of wafting around in my lovely coupe for me!

Thanks for your help!

cheers,

Nik

 

[shirubaby]

Hello there,
Can I have the wiring diagram as well. PLEASE!

I've recently bought an early christmas pressie (a 300ce sportsline coupe). I've found several vacume related problems. Economy guage not working, headlight height adjustment, rear headrests not dropping down and the front seat locks. Checked the cavity underneath the rear passenger seat, only to find NOTHING except disconnected vacume tubes and connectors. I need to replace these items. the diagram would help. Cheers. Shiru

 

[paulcallender]

There are no wires involved (at least, not on the W114) but there are a bunch of vacuum tubes. I assume you mean this?

 

[shirubaby]

There are no wires involved (at least, not on the W114) but there are a bunch of vacuum tubes. I assume you mean this?

Hi Paul,

Ummmm, then what are those 'unconnected' connectors for, I wonder. Looks like I'll have to do some electrical tracing.
Can I have any diagrams of the vacume diagrams that you have for this area, pleeeease!

Cheers - Shiru

 

[shirubaby]

Okay, I think we are talking about two different aspects of the same system..so lets start again!

The vacume tubes from the seat backrest locks go (from the attached solenoids) to some kinda unit underneath the REAR passenger seat...Does anybody have an idea what this unit/units are?

Further the vacume tubes from the REAR HEADREST also end in this cavity and connected to some unit (I know not what). Any idea?

Shiru

So vacume solenoids that are being talked previously were misleading me. Happens to me alot.

 

[shirubaby]

OK problem now sorted,
There are 2 components underneath the rear passenger seat.
1/ vacume control module to make the front seat backrest lock.
2/ vacume control module to make the rear headrests collapse.
Both units have electrical connections and vacume connections.
They are reasonably priced at mercedes dealers so replacing them was no hardship.

Thnks for the interest
shiru

 

[turnipsock]

...aktually, it wasn't for this thread I wouldn't have noticed that my seats locked. I checked them and they lock when driving. The headrests also go down when I hit the button.

 

[docmercquad]

Thanks to everyone for their help and advice - the seats are now sorted (kind of) - they both lock in place, and both will tip forward if you press both buttons at the same time, or the passenger side works ok on it's own.

Anyway, good enough for me - passed it's MoT so that's another year of wafting around in my lovely coupe for me!

Thanks for your help!

cheers,

Nik

Hello Nik,
I have a similar problem with my E320 coupe seats not locking. The vacuum unit, part number 124 800 08 75 is leaking. I cannot separate the steel cables from the vacuum unit. How did you do it? My Mercedes dealer cant help.
Thanks,
Peter Watson
Scottish Borders.

 

[Ivan Mihov]

I know it is a bit complicate job , but at first can you have a look the vacuum pipes for a damage under a seats. You have an expanding tank ( i do not remember where is located ) If you found it it will be easy to trace the problem. I think only the rubber connections get failed , but we never know
BTW is the headlights levelling working ?

 

[docmercquad]

Hello Ivan. Thanks for your message. The unit I am talking about is a black plastic box measuring about 3inches by 3 inches by 1.5 inches located under the seat. Part number 124 800 08 75. It has a vacuum line coming in and two steel wires coming out. It is the seat back locking modulator. I have a new one sitting here waiting to go in, but I cannot separate the steel wirers from the plastic box. I know the old unit is leaking. I have tested it with my vacuum gauge. The headlight levelling is working, but I suspect not 100 percent. The idling speed is high on start up all pointing to a vacuum leak.
Any ideas of how to get this seat vacuum unit free from the steel wires?
Thanks,
Peter.