My backup warning system is starting to go haywire, the little beeper making a long continuous beep and then not working, later correcting itself and working, and then back to the long beep. Contacted Volvo Customer Relations in Goteborg who told me to check the wiring harness or exchange parts with another owner to see what works and what doesn't, and no, we can't/won't release manufacturing data. I did check the wiring, exchanging parts is nonsense. I need to find out whether it's a single sensor that is bad or the little cigarette size computer. I've cleaned the outside of the sensors, know all about the paint problem, and have eliminated all but a defective sensor or the computer. I've given it my best shot and really need some outside help on this one, which I hope the manufacturer can provide (or a really knowledgeable Volvo mechanic/afficionado).