As I was driving my 2009 GL320 in to work, the power steering just stopped and after about 20 seconds of driving with no power steering, the battery light came on. So, when I got to the office, which was not far, I opened the hood and checked the reservoir and it is still full. No leaks or fluid loss. Sounds like maybe a bad pump or maybe just a fuse. Anyone else have this happen or have any ideas?

 

Pump is going!

 

If the battery light came on, that could be an indicator that the alternator wasn't supplying any juice... because the alt pulley wasn't spinning... because the belt wasn't spinning... because the power steering pump's pulley froze up thereby stopping the belt (or slowing it down).