I've had my 2001 Toyota tundra for 4 years and it has been very reliable. Recently I've had it die on me and after a bit of multimeter testing I belive it is the alternator. The battery is relatively new, takes a charge, shows good voltage in its own, and starts the truck fine. After some driving the battery light came back on. When I tested with the truck running, battery voltage was about 11.8-11.9 V. So I pulled the alternator and find it is absolutely covered in oil and grime - no wonder! The power steering pump is also covered. Any suggestions on a likely source or what to check?