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Power Seat Question

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

Reply to
John Gustafson
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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

Reply to
Gus

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

Reply to
K Bourke

In article , snipped-for-privacy@cox.net by Gus dropped his wrench, scratched his head and mumbled,

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

Reply to
volvowrench

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...)

T>

Reply to
Tony Rairden

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

Reply to
Tony Rairden

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