[GonzoF1]

Hello again everyone.

I just wanted to get your opinion on why my lights are pulsating. I'm guessing it's the voltage regulator, but I just wanted to be sure before I tried to chase an electrical gremlin. There is not change based on engine speed and does it even when driving at highway speeds. It's a subtle pulse, but it bugs the snot out of me.

[ctgross]

Welcome to the pulsating club I've fought this with my 66 for about three years , George K.(elec. guru IMHO) says most likely bad ground, but.....I've got more grounds than Carter has peanuts and it still does it after installing three different Volt. Regs.(one seemed to fix it for a short time, then it was worse than before, so I put one of the older ones back on and it now just flickers a bit???? I hope you can figure it out.....cause I damn sure can't

[george kujanski]

First and foremost, the regulator body must be well grounded to the firewall. A star lockwasher under a mounting bolt will help pierce the metal to accomplish this.

Secondly, the firewall must be electrically connected well to the engine, and that is usually done with ground straps from the firewall to the engine.

It could also be broken or corroded resistors on the underside of the regulator, but probably not in ctgross' case since he changed regulators.

A bad contact in the voltage sensing relay in the reg could do it.

Here's a description of what is probably happening:

Inside the reg there is a relay device which pulls on a moving armature which has a set of contacts. There are also a fixed contact above and a fixed one below the moving one. The movable one connects to the alt field and also to a set of resistors under the reg.

When it's running, the battery voltage coming in on term 3 of the reg is connected to the coil of the voltage sensing relay. the top fixed contact is connected to the battery also. Now if the bat voltage is too low, the moving field contact is pulled by a spring up to the battery caontact, the field gets bat voltage, and the alt output voltage goes up, the lights get brighter.

If the voltage gets too high, the moving conatct is pulled down against the bottom fixed contact, which is ground. The field is now grounded, the alt output voltage comes down, the lights get dimmer.

The moving contact is also in between the two fixed contacts during it's travel. At this time, the field gets some voltage thru the resistors underneath so the alt output changes only slightly, to modulate the voltage variations, so the field is not always fully on or fully off. (that would make the lights flicker).

Grounds are important because the voltage sensing coil is measuring the voltage from term 3 (bat +) to ground (which must be bat -). The resistors also are connected to the metal body along with the coil. Therefore a poor ground connection (or a poor term 3 connection) for that matter, will cause poor voltage sensing.

I hope that takes some of the mystery out of it.

george

[GonzoF1]

WOW! That should 'bout do it. So I should just check my grounds first? That's free! I like free! Thanks George. I'll get on it once I figure out these bodged brakes... hehe

[Rugratman]

Those star washers are the way to go with any ground wire.
I went thru 3 reg's too before I found one that was reliable. This last one has been on there for over a year and not one nary of a problem.

[ctgross]

Rug, you remember what brand was finally the charm? The last two I bought were "Bluestreak", one seemed to work good for awhile, then back to the same ole blink

[63Banshee]

How about a 1 wire alternator conversion?

[decco37]

There is one more item you may want to look at. I had the same problem, and found that my fuse in the fuse block was not making a good contact. The fuseholder in the block was somewhat corroded, and the fuse was making kind of an intermittent contact. I cleaned the contacts, and the problem was solved. I, too, had been through all the ground situations, with limited result, changed the alternator and regulator, etc.But the fuse fixed it. Best of luck. Decco.

[GonzoF1]

Yea, I cleaned the fuse contacts not too long ago when I was trying to make heads or tails out of the bodged wiring in it. Thanks for the thought.

[Bucksnort]

Had same problem - single wire conversion solved it. Brought the alternator into a shop for a rebuild and they converted it to a single wire setup at the same time.

[GonzoF1]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by bucksnort:
Had same problem - single wire conversion solved it. Brought the alternator into a shop for a rebuild and they converted it to a single wire setup at the same time. </div></BLOCKQUOTE>

Please explain? What does it do and what did it cost? I assume it uses the chassis as ground and the field coil is the only wire output then? Right or wrong?

[Bucksnort]

Hi Gonzo

I don't have the wiring specifics at hand but if you do a search on single wire or look thru the electrical section you will find much detail on this topic. That's where I found how to do it. You need an internally regulated alternator and then with a few simple wire changes it eliminates the external regulator. I gutted my external regulator and made necessary wiring connections inside. Kept the original harness as is and everything looks original on the firewall. Only cost I had was the alternator. Not sure if this is the best way to go but it seems many have done it and it sure elimninated my pulsating lights problem (and I have had no issues)