Finally solved my particular low voltage issue. Turns out it was a loose battery ground cable, the cable that goes from the negative battery post to the car body. Loose connection at car body attachment point. Very easy to check this and if yours is loose and you see carbon deposits on the cable or the fastener, these must be thoroughly cleaned. Merely tightening the fastener won't solve the problem.
Last edited by aurelius; 12-23-2013 at 02:05 PM.