2010 Volvo S80 AWD. I have a constant beeping or alarm noise. Every ten seconds for five seconds. Seems to be coming from back seat area. Cleaned all sensors. Got back in car. Volume of beep is barely audible but still there. Side alert lights on door post not working. The alert (light reflection on drivers side windshield when approaching a car ahead) not working. Any info on this?Can anyone tell me what is the best diagnostic scanner for this car?