Does anyone know how door mirrors remember their position?

Discussion in 'Electronics' started by lxi, Nov 19, 2014.

  1. lxi

    lxi Active Member

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    The car has misbehaved a few times of late.

    The door mirror positions (and seat & wheel etc) are set in the memory per normal.

    When I select reverse, the passenger door mirror dips so I can see the rear wheel.

    A few times of late though, it seems to lose the place (literally) and either the dip view is showing the ground about two feet from the car or when it returns to what should be the normal position, again it's showing somewhere several feet to the side.

    I've started from first principles - set the normal driving position, press M and 1 at the same time - it beeps and all fine.

    Set the reversing position - press M then press adjuster again quickly - stored.

    Works fine an indeterminate number of times, then decides I must be bored with the view & shows me somewhere else instead.

    When it does this, if I press & hold the 1 on the seat memory, it realises the error of its ways & goes back to where it should be.

    It has the "auto fold on lock" enabled and I've seen much mention of wires breaking, but I'd be grateful to anyone who has seen (& solved) similar if they would enlighten me as to what is going wrong.
     
  2. KillerHERTZ

    KillerHERTZ Administrator Staff Member

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    The side mirror will only dip when your reversing when you have it selected on the left/right control (if you get me), if you leave the drivers side selected it wont dip.
     
    Last edited: Nov 19, 2014
  3. OP
    OP
    lxi

    lxi Active Member

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    True - in my case that mirror is permanently selected so always dips on reversing, but it started sometimes showing a spot about 3 feet away from the wheel and when it (should have) reset as I drive off, it's showing somewhere away off to the offside.

    Correct height, just miles out. Press the seat preset button & it comes back to where it should be :crazy:
     
  4. markmifsud

    markmifsud MB Enthusiast

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    Could be one of the travel sensors not reading correctly, but first try a squirt or 2 of some PTFE into the motor gearing
     
  5. SPX

    SPX MB Club Veteran

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    I've found (in numerous Mercedes) that if you engage drive too quickly after reverse, it sort of baffles the car and the mirror behaves like an old lady looking for her glasses.
     
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  6. OP
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    lxi

    lxi Active Member

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    I'll certainly give that a try. Do you know where the sensors are (I presume in the mirror housing, but always worth getting confirmation!)?
     
  7. markmifsud

    markmifsud MB Enthusiast

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    I think the counters are in the mirror motor, but thats just a guess as I cannot see anywhere else they could be.
     
  8. OP
    OP
    lxi

    lxi Active Member

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    I've got a theory to try - when I reset, I buzzed the mirror down as far as it goes so I could see the wheel - I then tried to bring it "in" a bit, but it wouldn't move any more.

    I wonder if that attempt somehow registered so when it went back to what should have been normal, it factored back in the (non) adjustment sending it way out to the side.

    I shall report back!
     
  9. richard

    richard Authorised Forum Sponsor Authorised Forum Sponsor

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    The round thing that the mirror glass clips onto contains the position sensors and adjustment motors. There is an identical shape part (with less wires) that just has the motors for non-memory mirrors

    Richard
     
  10. Spin_bowler

    Spin_bowler MB Enthusiast

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    In my experience, The other one that seems to baffle is if you switch the ignition off after reversing before the mirror has had a chance to 'go home' it's then a complete lottery where it'll be pointing when you start up.
     

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