Power Seat Question

Discussion in 'General Motoring' started by John Gustafson, Jun 28, 2003.

  1. The passenger side power seat on our Volvo 850 (95) stopped working properly
    a couple of weeks ago. It would recline the seatback but would not move it
    back up (each time the switch was pushed it only moved a small fraction).
    My mechanic (who I've used for some time and trust) diagnosed the problems
    as a faulty seat switch. $400 later, the switch now brings the seatback up,
    but not all the way. We can get it all the way up by repeatedly pushing the
    button, but it will not raise all the way up in one motion. The interesting
    bit is that the seat moves smoothly up to the up right position when using
    the memory buttons (e.g., once we had it up we stored that position in
    memory).

    I'm clearly going to take it back to my mechanic and have them complete the
    repair, but thought I would ask the group if any one has had a similar
    experience and if so, what the problem and final solutions where.

    Thanks,

    Gus
     
    John Gustafson, Jun 28, 2003
    #1
  2. John Gustafson

    Gus Guest

    We did have a similar problem on the driver's side that was the 'known'
    cable problem (about $140 to replace). This time the seat does move, so I'm
    fairly sure it is not the cable. It behaves more like the override switch
    (that stops the seat when it runs into something) kicks in early. Anyway,
    thanks for the input and advice.

    John
     
    Gus, Jun 28, 2003
    #2
  3. John Gustafson

    K Bourke Guest

    Had the same problem win my '93 850, and was advised it was the "known cable
    problem" ....

    Turned out to be the resistor/potentiometer as Bob describes, and resulted
    in a *much* cheaper/easier fix.

    Kevin
     
    K Bourke, Jun 28, 2003
    #3
  4. John Gustafson

    volvowrench Guest

    The control unit measures the load on the motor. When the seat is run all
    the way back until it begins to compress the rear seat cushion, the load
    goes up dramatically. The control unit measures the resistance across the
    linear pot at that point, calls that one end point and calculates the
    other end point based on a preset value for degrees/ohm up to a design
    standard of whatever it is (120-135 degrees, I would guess).

    Since the old value remains in memory the seat back stops prematurely. By
    forcing the seat forward a little bit at a time you extend the forward
    limit. Kind of like sliding a tab on an old typewriter.

    Bob
     
    volvowrench, Jun 29, 2003
    #4
  5. John Gustafson

    Tony Rairden Guest

    I just had the seat back angle adjust on my '95 854T fail; my Used Volvo
    specialist dealer (JR's Vovo [sic, due to Volvo's lawyers...] Sales in
    Louisville, KY) diagnosed it as cable breakage or disengagement... I'm
    hoping for the latter... (I guess I may be better off with a non-power pax
    seat than with both power...)

    Tony Rairden
     
    Tony Rairden, Jul 25, 2003
    #5
  6. John Gustafson

    Tony Rairden Guest

    When the limit switch "learning" is the problem, does the motor run at all?
    I can hear it (different pitches for up and back) when I hit the switch,
    which makes me think cable disengagement or break rather than limit switch
    malfunction...

    Tony Rairden
     
    Tony Rairden, Jul 25, 2003
    #6
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