[s-cars] Heater Wire

Wayne Dohnal wd1 at hevanet.com
Fri Oct 28 01:20:51 EDT 2005

>Any thought that the wire in the seats is plain old nichrome wire with a
>set resistance.  The more juice you feed into the wire, the hotter it
>gets.  Simple but effective.

I  don't know what kind of wire it is, but the controller has it either off,
or running at full blast.  The heat is regulated by the controller turning
it on and off at whatever duty cycle it needs to maintain the desired
temperature.  That's why the controller doesn't need a big heat sink.

I think the best place to troubleshoot is at the 6-pin connector under the
seat.  On the seat side of the connector, 2 of the pins are for the seat
element, 2 for the backrest element, and 2 for the thermistor.  On the
harness side of the connector, the thermistor wires and one of the seat
wires go to the controller, one of the backrest wires goes to ground, and
the other seat and backrest wires are connected together.

Pins 2 and 4, black/white and brown/yellow, are the thermistor wires.
Pin 3, brown, is the ground for one side of the backrest element.
Pin 1, blue/yellow, if the power feed from the controller to one side of the
seat element.
Pins 5 and 6, brown/blue, is the series-circuit jumper from the seat to the
backrest element.

My brain vaguely remembers that the cold resistance of each element is a
little over an ohm.

Wayne Dohnal
1994 S4

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