I had the same problem. ABS module was fix by a local non-volvo guy and worked like a charm. No more speedo problems nor ABS and Brake failure lights as well. Good Luck

I had exactly the same problem on my 99 V-70. The bas smell and the fogging in the windshield as well. Plus lots of that stinking liquid in the car´s upholstery (your next step). Finally replaced the heater core (without removing the whole dashboard, you enter from below central console in the drive...