I had a very perplexing issue and the solution was completely unexpected to me.
I have put a nice sound system in my Dart. Alpine head unit with a matching amplifier. A Retro Sound dual cone stereo speaker in the dash top. 5 1/4" Kicker speakers in the kick panels. A JBL Basepro Hub powered subwoofer for the spare tire well. An Axxess wireless steering wheel controller in the driver's side armrest. Not professional, but fills the car with sound even with the top down.
I don't exactly know when it started , but the stereo would crap out intermittently after starting the Dart and then start working fine. Seemed like it was caused by low rpm and going downhill/ braking. So to troubleshoot I started tracing power leads to the head unit and amplifier thinking that there was a loose connection. Spent a lot of time on and off with no real success. Key here was intermittent. I would change something on the circuit and it would seem better, but not fixed. Then I started thinking that one of the components was failing or needed to warm up and started researching that aspect. Interesting that a tidbit on the Internet mentioned the amplifier glitching from power fluctuations.
I was sick and tired of crawling around and tracing wires. There are a lot of wires under my dash and it is very crowded because of all the gauges I installed to track the supercharger. So I broke out the multimeter and started looking at voltage right after starting the car. Lo and behold it was going wild and spiking over 16 volts, yikes! The ammeter didn't look that bad, maybe because I have a lot of relays - headlights, cooling fan, and fuel pump?
So, based on SlantSixDan's recommendations I sent the 2nd field wire to ground. No joy! I then started doing another of his recommendations and what seemed to fix my D100 charging issues. I ran a dedicated ground from the alternator to the regulator. I hesitated on running it to the battery because I had relocated it into the trunk to make room for the cold air intake and didn't relish tearing up the interior to run yet another wire the length of the car. This ground kept the voltage under 16 but the ammeter was showing random charging and discharging while test driving. So I broke down and ran a dedicated ground from the regulator to the battery. No joy again!
So you've probably guessed by now that the VR101 was wonky. Sure enough, I swapped in a cheap solid state regulator that I had used to troubleshoot my D100 charging and wam bam thank you ma’am, everything was fixed.
Stereo doesn't crap out at startup, the ammeter is acting sanely with no wild fluctuations, and the voltage stays below 14.5 vdc.
So after the fact I bought a cheap accessory plug volt meter and checked my others cars as well. It doesn’t work in the cigar lighter, but I have installed accessory plugs for external device management..
Thought that maybe my trials and tribulations might help somebody. 

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Cheers, Bill.
Smoke em if you got em.

Once upon a time I was on my way to work in my 1988 dodge daytona turbo. As I was coming off the off ramp my sony stereo stopped working entirely. It just shut off and then came back on a few seconds later. When I got to the bottom of the ramp my alternator belt started screaming and then got quiet again. I started moving at the green light drove a few hundred feet to another red light and it started screaming again. I turned it off to wait for the green. When I started it up it was quiet with no noises, the alternator belt was not present a few hundred feet later when I pulled into my parking space. The alternator had stuck on full charge, got very very hot, when I turned the engine off the stationary belt melted at the ALT pulley.

Just something else to also consider when you see overvolt issues on a car. I bet when you had 16+ volts your headlights had some lumens in them, SSD probably has a chart for the voltage to lumen curve for normal halogens.

Filament bulb math:

Wattage change is exponential to the power 1.6 with voltage change.
Output change is exponential to the power 3.4 with voltage change.
Lifespan change is exponential to the power -13 (negative 13) with voltage change.

Example: a bulb rated 55 watts, 1,000 lumens, and 1,000 hours at 12.8 volts.

Feed it 14 volts instead:

14 ÷ 12.8 = 1.09375

1.09375^1.6 = 1.154 wattage multiplier (1.154 × 55 = 63.5w @ 14v)

1.09375^3.4 = 1.356 output multiplier (1.356 × 1,000 = 1,356 Lm @ 14v)

1.09375^-13 = 0.312 lifespan multiplier (0.312 × 1,000 = 312 Hr @ 14v)

Works the other direction, too. Run that bulb at 11.6 volts:

11.6 ÷ 12.8 = 0.9063

0.9063^1.6 = 0.854 wattage multiplier (0.854 × 55 = 47w @ 11.6v)

0.9063^3.4 = 0.716 output multiplier (0.716 × 1,000 = 716 Lm @ 11.6v)

0.9063^-13 = 3.593 lifespan multiplier (3.593 × 1,000 = 3,593 Hr @ 11.6v)


Let's hit that bulb with 18v and watch what happens to lifespan:

(18 ÷ 12.8 )^-13 = 0.012 = less than 12 hours' lifespan at 18v, but that's academic because the filament probably made like a flashbulb.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Here is the voltmeter gadget I got to easily see battery stuff without the multimeter hassle if you only have an ammeter and you have added an accessory plug. Cheap Chinesium from Amazon but seems helpful to me.

_________________
Cheers, Bill.
Smoke em if you got em.