Date registered: Feb 2010
Vehicle: 1972 280SEL daily driver. 904 Dark Blue with cognac interior. euro 4.5 engine
Location: Williamsburg, VA
Mentioned: 3 Post(s)
Quoted: 39 Post(s)
So, problem solved. It is actually the alternator which is bad, but not for the normal reasons. The plug on the back of the alternator is held in place by a couple of plastic tabs, or should I say it is supposed to be held in place by a couple of tabs. My plug is being held in place by force of habit, which is not strong enough apparently.
When you wiggle the plug, voltage will spike to about 16-17v and then you wiggle it again and it comes back to 13.5v.
I did make a new harness from the alternator to the regulator as the old one was pretty beat up. All three wires into the alternator had their insulation broken from fatigue at the connector. One of them only had about a third of the copper strands left in tact.
So, alternator on order, new regulator, new harness....hopefully case closed.