Sounds more like a ground problem than an alternator problem to me.
I believe there is a large bolt somewhere on the steering column that attaches the ground wiring from the dash cluster. That may be the first place to look.
Check your battery with a voltmeter with engine off, then on. Should be 11.5 - 12V off, and 13.5 to 14.4V when on (accessories off).
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car