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Old 09-25-2007, 08:34 PM
TheEngineer's Avatar
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Join Date: Sep 2007
Location: West Seattle, WA
Posts: 89
Headrest failure

On my '95 E320 Wagon (W124) The headrest on the driver's seat does not move when I move the button. On the passenger side it works fine. I can hear the motor running in the driver's seat. I have removed the headrest & installed it again. Anyone who has been in the seatback to fix this? The shop manual is silent on this. Thanks!

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Old 09-25-2007, 08:48 PM
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Join Date: May 2007
Location: florida
Posts: 677
Once you get the back off the seat you will see what the deal is.My son had that problem on his 93 300d and was able to get the drive gear snapped back in place and secured with a couple of wire ties. Lubricating the tubes that attach to the head rest to make it slide up and down easily should prevent its breaking again in the near future. My $.02 Don
Red Green "This is only temporary,Unless it works!"

97 E300D 157000 miles
87 300TD ?141k? miles
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Old 09-26-2007, 09:14 PM
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Location: West Seattle, WA
Posts: 89
Thank you, Old Diesel for your reply. I have tried to remove the seat-back. There are two screws in the bottom. I have removed those, but I cannot see how to remove the seat-back. Yes - I know - it's easy, once you know how. Instructions please! Thanks!
Today I removed the seatback. Actually, I just had to move it down about 12 inches to expose the mechanism. It's easy once you have done it. I found that the rack had jumped out of the case that holds the pinion. That case is broken. The reason is, that the motor that drives the pinion does not stop. There is a switch attached to the motor that counts revolutions and turns the motor off before the rack reaches the end of the allowable travel. When the switch doesn't work, the motor doesn't stop and breaks things. When I get everything working I'll report back in.

Last edited by TheEngineer; 09-27-2007 at 10:59 PM.
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Old 09-30-2007, 04:21 PM
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Location: West Seattle, WA
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Yesterday I looked at the mechanism that adjusts the headrest: There is a small motor with a gearbox that drives a small gear that engages a rack which moves the headrest. A potentiometer attached to the gearbox sends a signal to a computer chip. That determines when to shut the motor off when the headrest reaches the end of the allowable travel. If it would not shut off the motor, it would break the weakest link. The weakest link is the plastic rack. It broke. The potentiometer signal is also used to position the headrest to a saved position using the "save" button on the door. Because the computer chip has failed, the motor doesn't shut off. I have disconnected the motor and I'm positioning the headrest by hand. Until now I have never appreciated the simpler things: I'm so very grateful now that the zipper on my pants was not engineered by Mercedes.
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Old 09-30-2007, 07:14 PM
190eand me's Avatar
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Join Date: Aug 2007
Posts: 55
right on

i enjoyed your were right on with the zipper comment

I find that I have re-engineered allot of my MB project car.

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