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Re: Seat heater switches
In message <36166E3D.email@example.com> Huw Powell writes:
> > The seat heater switches in the ur-quattro are the thumbwheel type -
> > On/off when moving from 0 to 1, and then gradually more heat up to
> > a setting of 6.
> > Anyone know the nominal resistance for each setting?
> The resistance of the heater wire?
> Because the switches like that that I have seen are just that -
> switches, with 7 positions. They go to a pair of relays, then to the
> three heater wires. The six settings are the different combinations of
> the three different resistance wires...
> hth a little? I don't have any heated seats around so I can't answer
> the other half of the question.
No. There is only _one_ heater wire - the backrest and squab are wired
in series, and there's only one circuit back to the controller.
I suspect the switch presents on/off and six different resistances
to the controller. The controller applies a voltage to the switch
resistance and to the thermistor in the seat element. All it would
have to do is amplify the delta current and apply it to a relay via
At least, that's the only mode of operation I can deduce from the
paucity of physical circuits present.
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