Lights and accessories fluctuating (some thoughts and thanks)

[Batesy]

First, I am pretty new to the forums. Second, even though i am in my mid-40's, I am also new to owning a classic car and working on it myself.
I have a very generous friend who has been guiding me when things come up. I have recently had an electrical issue come up that he and i researched online here both on this forum and other places.
Before I go any further, I really want to thank 67Dart273 who, more than anyone else on here, has PATIENTLY answered the same questions over and over on this forum and offered up great advice to everyone who comes on here with (very often) the same handful of electrical problems.
I, too, had the electrical gremlins that caused my lights (internal/external) and accessories to pulsate, flicker, etc. I have a 75 Swinger. After reading a number of posts and articles, I went ahead and did the MAD bypass but my problems continued. I posted a video to show someone my problem here [ame="https://www.youtube.com/watch?v=qAPM4F3rd0M"]https://www.youtube.com/watch?v=qAPM4F3rd0M[/ame]
Anyway, just to encourage others, after reading up on other posts, i went back and checked my grounds at the alternator, battery, etc. Turned out my alternator ground was very loose. Tightened it down and BAM, the pulsating stopped! Now, I still have a problem where things get brighter, stronger when I give it some gas and drive and then go back down at idle but I am going to continue troubleshooting based on what i have read here. So if you are new and have a lights problem, check your grounds first. It quickly solved my biggest problem -pulsating lights/power.
Thanks to everyone on here for taking the time to post helpful responses to problems.

 

[67Dart273]

You're welcome. The older alternators both because they are typically less total output, and because many models don't have good low RPM output, are going to vary voltage output moreso than more modern units. Without going to a more modern alternator I don't know what you could do.

First step if you want to improve it further is to see just how much the system varies say, at night from idle and up

Frankly, I'm so old I just ignore it. My first couple / three cars all had generators. This was par for the course back then, and long before anybody ran big stereos, or any other accessories.

When I grew up, several of our cars were six volts. My dad had several old 50's pickups, GMC, Chev, and Stude, and the first cars I remember was a 53? Ford, 54 Nash, and 55 Rambler. Hell some of those had vacuum wipers, LOL you ought'a strap THOSE on in a snowstorm!!!!

My "young" cars were

57 Chev,.........55 Chev............56 Chev............60 Falcon............62 Chev pickup.............. Even in '74 when I first bought the later, 340 powered 62 FJ-40, that thing had a wore out 283 with a ............generator

 

[RedFish]

I could be wrong. If my memory serves correct, the BATT wire in the 75 harness is waaaay undersized. I think they did this when they added a connector in the engine harness. You could test my theory with a larger wire as temporary upgrade. You could even use a booster cable but be very careful with those huge clamps. We wouldn't want sparks flying.

 

[Batesy]

I could be wrong. If my memory serves correct, the BATT wire in the 75 harness is waaaay undersized. I think they did this when they added a connector in the engine harness. You could test my theory with a larger wire as temporary upgrade. You could even use a booster cable but be very careful with those huge clamps. We wouldn't want sparks flying.

Many thanks RedFish, I will look into this this weekend.

 

[CharlieRotten]

My 73 duster was doing the same thing.

It started with my aftermarket tach jumping all over the place, then my lights (in and out) were intermittently on and off.

It progressed to my turn signal squealing through the radio and my tack going so out of whack that it broke.

It all finished off when my volt meter pegged past 18 and then the car wouldn't start

I replaced the voltage regulator and tried to diagnose further.

I'm going to end up having to replace the fuse box and there is a terminal behind the brake petal that is melted and will have to come out too. I hope before i get the car going again (currently a broken wrist pin) I can pull the dash and rewire everything.