I am looking at a 2008 XC90 3.2 AWD with 135k miles, but the traction control light is on and there is a whirring sound that seems to be coming from the drivetrain. Any thoughts on what this might be? Other than this, the car is in great shape, so I just want to make sure I cover myself for any major issues.

Thanks,
Rich

 

Traction control light can be on because of:
Bad SAS (wheel angle sensor)
Bad ABS sensor or impulse ring. It this case ABS light should also be on.
Bad DEM (Differential Control Module)