My 2002 XC70 is "new" to me. The winter mode button below the automatic gearshift does not depress orotherwise "engage" this button. According to Volvo service this is true. I guess b/c it is an AWD you don't have to "engage" winter mode?????? I did notice yesterday with the snow that when traction broke, a tri-angular light came on the dashboard; assuming it is the traction control light??????
Volvo service told me that the winter mode LED light would light up when the wheels were slipping or engaging in bad conditions. True?????

 

Yes...I believe if a car has traction control, and the wheels spin, the light will come on.
Not sure about winter mode, because it is an AWD, unless it moves the power toward the front wheels like an EVO.
"Note that this light is not really helpfull, because you will know and feel the car breaking loose, and the little light on the dash won't tell you how to apply the correct amount of counter steer."