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  #1  
Old 06-08-1999, 03:30 AM
John H
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Seems that the car gremlins have decided to limit the recline function of my driver's seat. While this is of minor concern to me as I have my position in memory it has my all too often designated driver in a snit.

The seat can be tilted forward via the door switch but not back. The only way it reclines is by the memory button (I therefore assume it is not the seat motor). I pulled the door switch apart and all the contacts were fine. I even tried to jumping it but could only make the tilt go forward not rearward. Are there any other tests to perform before I consider replacing the computer (or my complaining friend). Thanks.

John
  #2  
Old 06-08-1999, 01:44 PM
MB STARS
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John
your problem is the power seat switch
I have seen a lot switch go bad.

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MB STARS Master Guild Technician,12 years MB tech
5 years independent shop owner
  #3  
Old 06-08-1999, 02:35 PM
John H
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Thanks for taking the time to post.
I have bypassed the switch with a jumper lead to no avail but will double check it again. If it's not the switch any suggestions?

JH

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  #4  
Old 06-08-1999, 10:42 PM
Benzmac
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IF it will work with the memory but not the switch, it is the switch at fault.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM


  #5  
Old 06-16-1999, 01:47 AM
John H
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Continuity of switch ckecks out OK. Additionally I swapped the leads on the back of the terminal block and what should have been the dead side of the switch functions fine. To me, these tests indicate the switch is not the problem.
I also checked the voltage going to seat all switchs. All of the poles which control seat action have voltage (11+ volts) while the one seat function in question does not. This was done at the terminal block when unplugged from the switches.
Has anyone ever had a seat control box fail? Is there a way to test? I would prefer to test rather that throw parts at the problem.
Thanks for taking the time.

John H.
  #6  
Old 06-16-1999, 02:48 AM
Katttfishh
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My 92 190 has the same problem.
  #7  
Old 06-16-1999, 10:43 PM
Benzmac
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I think that if the seat moves in the memory and not with the physical switch, it almost always is the switch. In some cases the switch will check out while not in use, but the moment that you put a load on the circuit goes open.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM


  #8  
Old 06-16-1999, 11:39 PM
MB STARS
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John and Catttfishh

SWITCH!SWITCH!SWITCH!SWITCH!SWITCH!

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MB STARS Master Guild Technician,12 years MB tech
5 years independent shop owner
  #9  
Old 06-16-1999, 11:46 PM
E. Lee
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Just remove the switch from the door (2 screws) and take it apart. Beware of those ball bearings!! Take the switch apart only on a table where you won't lose all those springs and ball bearings. Then, clean EVERY single contacts (probably all blacken by now) with contact cleaner (or you can scrape the black stuff off with a small flat blade screw driver). After cleaning, you may want to spray a light coat of WD40 to protect the contacts. Then reassemble the switch. That's it! I did the above procedures 5 years ago and my switch has worked flawlessly since then.
  #10  
Old 06-17-1999, 03:21 AM
John H
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I am apparently not describing things correctly.

I switched the termininals on the back if the terminal block such that the switch is working in reverse. Before I switched the wires, the recline portion of the switch did not work. After I switched the wires I could push the switch in the recline position and the seat back moved forward (due to the swaped wires). The point of this is that I can make the seat go forward by connecting the forward terminal to either side of the switch! This would indicate that the switch is not the culprit. Conversly I connected the recline wire to the side of the switch which had previously worked and had no seat movement. Essentially I have isolated the switch and it is performing correctly. And E. Lee, the first thing I did was to take the switch apart and I cleaned/checked the contacts - a little di-electric grease on the eight detent balls works great to hold them in place.
I have a feeling it is a computer problem since the wire in question has no power while the other seat function wires do.
Where can I find the computer so that I can eliminate a possible wire failure (unlikely)from the switch to the computer?

Sorry to be such a block head but I am tired of replaceing parts that already work ( I have a whole shelf on the wall to store parts I replaced that didn't solve the problem). As always, thanks for your input.

John H.
  #11  
Old 06-17-1999, 04:47 AM
be459
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John,

The way you test the switch may not be good enough to verify it. It is because the power inputs of the seat motor may be "floating", therefore, both forward and backward contacts have to work together. This is just my wild guess without looking at the wiring diagram. I will check into the wiring diagram when I have a chance and let you know if I find anything about it.

David
  #12  
Old 06-17-1999, 10:11 PM
Benzmac
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be459, will you register?

John H. the control module is under the seat connected to the seat bottom. They are hard to get to. You will probably have to take out the seat to get at it. Good luck with the persuit.
PS I have seen some wires knocked off at the control module cause a simmilar problem.

------------------
Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM


  #13  
Old 06-21-1999, 02:20 AM
John H
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Thanks Benzmac

I found the computer under the seat like you said. It appears the inputs leads to the computer are at the front of the seat and the output leads at the rear. Pulled off the input lead terminal block and checked for switch continuity. All O.K. Then pluged terminal back into seat computer and the faulty system now works. Apparently the terminal block had come loose or was not making good contact.

I was so happy to have fixed my driver's seat problem I decided to tackle the non-functioning head rest on the passenger's side. A slight motor sound could be heard when the switch was moved in the up or down position. After removing the seat back (easy once you know how) I found a broken plastic rack and pinion like setup.

Thanks everyone for sticking with me on this even though I went against conventional wisdom.

John H.
  #14  
Old 06-21-1999, 02:51 AM
jack
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My 99 E430 driver's power seat failed twice during the first month of ownership.
  #15  
Old 06-23-1999, 05:52 AM
Jon Marc
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John H or ?

I have recently purchased a 1992 300TE with a passenger side headrest that will not move via the switch. I can move/remove it manually. I would really like to see the inside if it is easy. What are the details?

Also, the previous owner seems to have been a heavy weight. The drivers seat cushion (MB-Tex) feels dead compared to the passenger side and my 1986 190E. Any thoughts on replacing innards?

Thanks, JM
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