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Discussion Starter #1 (Edited)
I've been redoing my interior and months ago when I took off the rear passenger door panel, I broke the presenter rail. I got a replacement rail, pulled the entire presenter assembly (motor/rail/etc), and carefully swapped the rail. I made sure to keep the position of the tensioned screw the same and didn't touch the limiter, other than pulling it loose and the pushing it back into place

After I put almost everything together (including the seats, which I believe need to be plugged in for the presenter to function), I tried to activate the presenter and nothing happens

I pulled the door panel again (fun!) and now have very easy access to everything. This is a Gen 2 unit and I've been testing both when in key position 1 and position 2 with engine started
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I've tried the following:
  • pulling fuse 15; waiting 30 seconds (or longer)
  • unplugging the two cables going to the presenter relay and plugging them back in
  • using very mild force, carefully pulling the rail forward the prescribed 400mm
  • having the rail forward 400mm, pulling the fuse, waiting 30s, and then replacing and turning on car again
  • Released tension on the 8mm screw (see picture). No change. Put tension back, no change
  • Adjusted position of limiter; turned the screws slightly. Pushed the limiter button down manually
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In all the cases, basically nothing happens (other than me accidentally closing the door on myself and cussing a lot). If I do move the rail forward (doesn't matter how far), the motor will activate and retract the rail back into the default position. I can't seem to get it to extend. The motor is hot to the touch and definitely has power

The workshop manuals are interesting (82-890 / 82-891 / etc), as they describe how it's supposed to function, show a wiring diagram, and describe how to test the individual pins. But there aren't procedures (at least in my physical manual) for how to troubleshoot or adjust the limiter, etc. The workshop manual also shows the older Gen 1 unit.

Any ideas?

Threads I have read through:
 

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Discussion Starter #2
While searching, I did find procedure 91-508 (B) posted by @MBL87560SEC here:

Looking at this, I might need to pull the rail entirely. Seems the procedure to re-install a rail is:
  • remove rail entirely
  • have battery disconnected
  • gently push rail in ~30mm
  • reconnect battery
Will have to try this tomorrow and see what happens
 

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While searching, I did find procedure 91-508 (B) posted by @MBL87560SEC here:

Looking at this, I might need to pull the rail entirely. Seems the procedure to re-install a rail is:
  • remove rail entirely
  • have battery disconnected
  • gently push rail in ~30mm
  • reconnect battery
Will have to try this tomorrow and see what happens
Hey Brian,

How frustrating after all the work you have been doing!

A couple of ideas come to mind here regards to the presenter operation..
Please, you are probably aware already, but sometimes details get lost in the translation..

The presenter is meant to extend only with the door [/I]closed[/I].

On one of my cars, the little presenter control unit had a mind of its own at one point. I sourced another off ebay.... easy.

You said the presenter motor was hot to the touch. I would not expect this as a normal condition. That said, I don’t know all the extenuating circumstances involved there.

I wish i had more info here, but I am away from my MBCDs & all my notes at present.

Best of luck man.

M.
 

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Discussion Starter #4
Well dammit. Over lunch, I tried the proposed steps and no luck. Fed rail past the gear about 30 mm and plugged battery back in. Once battery was connected, the rail pulled itself back into the retracted position. Upon opening door, no change... Although I did see the motor move the rail about 2mm and stop
 

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With ignition on, open and close the door, then adjust the micro switch located by the tension spring until the arm extends.
 

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Discussion Starter #6
With ignition on, open and close the door, then adjust the micro switch located by the tension spring until the arm extends.
By micro switch, do you mean the limiter (pictured). Has two small screws and a button. I believe as the arm retracts, it's supposed to mechanically push the button to stop itself

I tried messing with it a lot more tonite, but no luck. My friend shared some wiring diagrams, so I checked those out. The seat belt is involved in the circuit- when belt is put into place, the presenter retracts. I was able to get some movement (including forward movement) when putting the belt in. After disconnecting the belt, I could also get the motor to move by physically pressing the button on the limiter.

Not really finding a correlation between things. Going to do some more research
 

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Discussion Starter #7
Wait a second - are there two limiter switches? (a front and back?)
 

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There are three micro switches. The one in your third pic is the one I’m talking about. The one by itself. With the seatbelt unbuckled ignition on the door opened then closed the arm should extend if that switch by that tension spring is adjusted properly. Just adjust the switch so that it is depressed. If that doesn’t work, adjust it so that the switch is not depressed. The other two switches are adjusted so that when the arms raised portion (on each end of the slot) by the switch the switch is depressed. I hope you’re following what I’m saying here.
 

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There are three micro switches. The one in your third pic is the one I’m talking about. The one by itself. With the seatbelt unbuckled ignition on the door opened then closed the arm should extend if that switch by that tension spring is adjusted properly. Just adjust the switch so that it is depressed. If that doesn’t work, adjust it so that the switch is not depressed. The other two switches are adjusted so that when the arms raised portion (on each end of the slot) is by the switch the switch is depressed. I hope you’re following what I’m saying here.
 

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Discussion Starter #10
Happy to report that I just finished solving this - pictures and details coming up next
 

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Discussion Starter #11
After not making any progress in the hot garage, I took the entire assembly out and brought it into the air conditioned house. Today, I decided to really understand how this works

My friend Bud shared some wiring diagrams with me from his old ETM book. It's worth noting there are 3 variations of the seat belt presenter; 81-85, 86-90, and 90-91. The wiring diagrams for 86 and newer are basically the same (I'm not sure what changed). Here are some pics he took from the physical ETM manual that I printed out
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With this in hand (along with the entire assembly pulled), I checked the wiring. Each of the wires that goes into the control module is basically shown above, although it's not obvious by any means. I'm a computer programmer, but I only have a very basic understanding of electronics. I started off by finding the switch I took a picture of above
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It's got a blue (BU) and brown (BR) wire running to it. So this is the force switch. It's engaged when the little yellow button on it gets pressed, which is only supposed to happen if the unit jams. At that point, I believe the unit will retract the rod all the way back in. I adjusted this so that the button is NOT pressing against the black assembly... but so that it's close enough that (if force greater than the spring is exerted) it can be pressed by the black plastic above it

Tracing the wires, I looked for the retracted, return travel, and extended switches. Huge thanks to @560300 for this post:

Using a small screwdriver and a little pressure, you can loosen the plastic limit switch cover from the metal tabs (on the side). You have to be super careful taking this off, because if you just wedge something in, you might move the other 3 switches.
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While there's only two switches visible, the one on the left has a switch behind it, so there are actually 3 total. Looking at the wiring, the one on the left is the extended switch (White (WT) / Blue(BU)). The one to the right of it is the return travel one inch switch (Yellow (YL) / Blue (BU)). Behind the extended switch is the retracted switch (Red (RD) / Gray (GY) / Blue (BU)). Remember, this is for the passenger (right) side, so the drivers side will be different.

Just to be clear (because it wasn't clear to me before finding this out), the screws have nothing to do with the problem (other than holding the switch into place). The important part is the little yellow button under the switch. Once everything is working, you'll want to secure the screws really well (tighten, super glue, whatever :) ) so they don't move

In my case, the extended and retracted switches were loose and the left side of the switch was lifted up. The solution was to just push this down a bit and then secure it.

How this works mechanically is pretty easy. With the wiring disconnected, you're safe to pull and push the rod (gently of course) and you can test how it works. On the very back of the rod, the plastic is lifted. As the motor runs and the rod extends, the raised part will eventually engage the return travel switch first and then the extended switch. Once both are engaged, the unit knows to move it back approximately one inch. If you pull the rod out, you can physically hear the click as the yellow buttons on the switch get pressed by the rod.

Similarly, the retract switch is triggered by the plastic notches in the front of the rod (which are adjustable). As this is retracting, it will eventually engage the retracted switch which will stop the motor
 

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Discussion Starter #12
Typing this up, it seems extremely easy in retrospect. Sometimes you just have to get into an air conditioned area, get a comfortable bench area, and spend some time messing with things (opposed to trying to fix it in the car, sweating everywhere, and breaking other trim pieces in the process). In my case, I believe the motor was getting hot because power was being sent to it the entire time (because the retract switch button was never being pushed). With things working regular, the motor was nice and cool to the touch, even after the key was in position 1 for a few minutes

As I re-installed the various parts, I tested the unit over and over (after putting the limit switch cover back on, after putting the rear door panel back on, after screwing that door panel). It's working great :)

If this info helps one person troubleshoot things, it was totally worth it :)
 

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Quote: It's worth noting there are 3 variations of the seat belt presenter; 81-85, 86-90, and 90-91.

Brian,

Thanks for your detail and photos. Is your quote above just for the wiring, or even the mechanical parts? I understand there are aluminum gear teeth wheels for the Gen 1 versions. I don't know if they changed to plastic/nylon for sheer cost savings, or as a sacrificial part to prevent something more costly from being ruined?
 

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Discussion Starter #15
Quote: It's worth noting there are 3 variations of the seat belt presenter; 81-85, 86-90, and 90-91.

Brian,

Thanks for your detail and photos. Is your quote above just for the wiring, or even the mechanical parts? I understand there are aluminum gear teeth wheels for the Gen 1 versions. I don't know if they changed to plastic/nylon for sheer cost savings, or as a sacrificial part to prevent something more costly from being ruined?
Hi Drew,

I didn't find any differences in wiring, so I'm not exactly sure what is new. Maybe the gears are better? Or different unit motor? Not sure

The docs I found state the 3rd iteration is from June 1990 and onward. I checked the gears, they look to be in great shape. Put some of that Gleitpaste on- should be good to go for a while
 
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