[W126 Coupe] Seat belt presenter + motor operation

[Dick Spellman]

Hi Aage,

It has been a long while since I worked on the extender circuit and gear.
The limit switch is designed to cycle the motor off when the arm reaches its
limit and to avoid dmaging those gears.  The fact that your gears are
running continuously is a concern.  What position is the extended arm while
this is happening?

The electrical circuit includes the seatbelt buckle (latch) and one of the
door pin switches.  The door pin switch provides state of door open (retract
arm) closed (extend arm).  This is 'anded' with the state of the seatbelt
latch. 1. buckled (no action) regardless of door state or 2. unbuckled and
door closed (extend arm).  I think that is the logic flow.

The limit switch is tied to motor cut-off only and is a function of the arms
position 1. fully retracted -stop the motor or 2. fully extended - stop the
motor.  The limit switch does require movement (motor torque) to activate.
This is the function that preserves the gears from being stipped and/or the
motor being damaged.

I hope this helps.  In terms of what you can do...Check the door pin switch
and then check the seatbelt fastener (latch) by disconnecting each from the
chassis electrical harness and reading the state change of each using a
simple VOHM meter.   Be careful not to lose the pin switch leads in the door
frame recess.   I have to pull the pin switch on my SEC to see what the
normal state is or perhaps someone else can chime in that knows.

Regards,
Dick

On Thu, Sep 2, 2010 at 2:15 AM, "Håland, Åge" <
aage.haaland at helse-vest-ikt.no> wrote:


>  Hi Dick.

> Thank you for your advice an .

>

> I opened the side panel and can see the 2 plastic gears running smoothly

> all the time; is the limit switch dependant of the plastic gears.

> What confuse me in addition is that the extender motor is running even the

> ignition is off and the fuse for extender motor is out.

> As a none technical person I can not understand this.

>

> If you have any additional information / ideas I wold have appreciate that

> very much.

>

> Have a nice day.

>

> Regars Aage

>

>  ------------------------------

> *Fra:* mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes-bounces at mbcoupes.com]

> *På vegne av* Dick Spellman

> *Sendt:* 1. september 2010 19:19

> *Til:* Mercedes Coupes Mailing Lists

> *Emne:* Re: [W126 Coupe] Seat belt presenter + motor operation

>

> Hi Asge,

>

> This sounds like a stripped gear on the extender arm motor (a common

> problem).  There is a limit switch that stops the motor when the arm

> retracts or extends to it's limits presuming the gears are okay.

>

> From the MB factory you have a nylon gear on the extender motor.  Go to

> this link for a detailed write-up done by Satish (this list's founder) for

> more info on how to repair.   <

> http://www.mbcoupes.com/repairarticles/seatbeltpresenter/seatbeltpresenter.htm

> >

>

> I made the repair he details in 2000 or 2001 on both arms using the metal

> gear originally built by Autolux.  They continue to work to this day.  I

> think George Murphy at Performance Analysis in Tennesee, USA  now makes or

> resells these aluminum replacement gears.

>

> Regards,

> Dick

>

> On Wed, Sep 1, 2010 at 2:23 AM, "Håland, Åge" <

> aage.haaland at helse-vest-ikt.no> wrote:

>

>>  Hello SEC-fans.

>>

>> I need some advice and help for my MB 420 SEC 1986 concerning the

>> motor/regulation for the Seat Belt Presenter. Suddenly the seat belt motor

>> started running all the time even the ignition is off and even the fuse

>> is out, that means running until the battery is flat. I opened the side

>> panel and and removed the el. plug from the motor connected to a black

>> box/regulation/operation as a first aid.  Questions: Is the problem the

>> motor in itself or the black box, is there any fuse, can the box be fixed.

>> I'm seeking the valuable experience out in the mbcoupes world.

>>

>> I would appreciate very much your advice.

>>

>> Regards

>> Aage Haaland

>> Norway

>>

>> The MB Coupes Website!

>> W126 SEC Mailing List

>> Postings remain property of MB Coupes, L.L.C.

>>

>

>

> The MB Coupes Website!

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> Postings remain property of MB Coupes, L.L.C.

>

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