Thank you ggleavitt for directing me to this thread. I tend to agree that the noise very well could be a bearing in the rear diff even though my mechanic believes it is coming from the AOC. I am aware that Volvo will only replace(not repair) the rear diff but that the diff bearings can be replaced u...

I have a 2007 XC90 V8 with 160,000 miles. I am hearing a constant noise audible at all speeds while driving. Diagnosed as coming from the Gen 3 Haldex coupler unit. Thanks no error messages and AWD functions normally.
Anyone with similar symptoms and repair experience?