I had the same issue with my Speedo. Here's what I did. Try to access an Autodiagnos Scan Tool with Volvo software. This will allow you to tap into the ABS module. You can watch all 4 wheel speed sensors, the Vehicle Speed, and Accelerometer. You'll notice all a data value for everything when the Speedo is working, but you'll lose any combination of one or all wheel speed sensors, and the Vehicle Speed Signal and Accelerometer. You're speedo consequently will stop working. It won't come back on unless you cycle the key. Sometimes this won't work. In any case, I'm a tech at an independant Volvo specialty shop. The bottom line is that these ABS modules are prone to failure. I recommend Module Masters. Look them up online. You'll need an inverted torx bit to remove the four small screws that retain the module to the ABS pump. Undo the 2 wire connector for the ABS pump and the multiplug connector (All other functions). Send them your module, and about 2 weeks and 130 bucks later, you'll have a functioning module with a warranty to back it.