Hi,
The heated seat pad is usually at fault, but not always. It can be tested for continuity by unplugging the connector underneath the seat and using a multimeter set to Ohms on the Black and Yellow wires (I think).You should get just a few Ohms if there's no problem, but most often the pad element will have broken and you will get no continuity. There are also (Blue)wires going up into the seat base to a thermistor in the seat back which senses the temperature and allows the control unit (switching unit in the dash) to turn the heating pad on and off at the correct times to keep a set temperature. The thermistor should be around 1400 Ohms if my memory serves me, it's a negative co-efficient type that decreases resistance as the temp' increases.
If the pad is OK, try swapping the control units across and see if the drivers seat springs into life. A mate had a unit go on him once.
If you do need to replace the pad, it takes around an hour and requires the removal of the seat. This is held down by four T50 torx bolts. Then the seat belt can come off (after removing the side cover - more torx bolts of various sizes). This allows the cover of the seat to be removed, quite an easy job as long as you have some long nose pliers or similar to pull down on the clips that secure the cover in the middle of the seat base, the're sprung quite tightly. A new pad can be stuck over the old one, they come from Saab with a self adhesive backing, and the wiring routed as per the original.
HTH
Nick.
