[W126 Coupe] Seat belt presenter + motor operation

["Håland, Åge"]

Hi Dick,
Thanky you very much for your advice concerning my problem and spending the time doing this. I would like to have your knowledge and experience to go further trying to solve  this "challenge". But your advice will be worthful when I find local experienced to help me. I have put som questions into your answer below and if you find time I would appreciate your thougths.
 
Thank you very much.
 
Regards, 
Aage
 
________________________________

Fra: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes-bounces at mbcoupes.com] På vegne av Dick Spellman
Sendt: 2. september 2010 17:29
Til: Mercedes Coupes Mailing Lists
Emne: Re: [W126 Coupe] Seat belt presenter + motor operation



	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 extended arm is out, the door is closed, the seat belt is off. I have tried different combinations door open/seatbelt on and vicaversa, the motor is running all the time.
	
	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.  Concerning limit switches- this is thecnnical switches which put a signal to the motor to stop? In some way I feel that the plastic gears is not a part of the problem or could they be???
	
	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.
	 I feel that the problem can be electrical disfunctions in one of the elements seat belts, door pin, switches, or in/to the ¨blackboxbrain(under the side panel) where I assume / a lot of el.threads meets from which there is a connection by the 6 or 8-pin connection to the motor????
	 
	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

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