Why is the light intensity on headlights pulsating??

[mysil bergsprekken]

Why do the lights intensity vary up and down, what might be wrong with the alternator, or perhaps something else?

[A383Wing]

voltage regulator is the problem.....I would change out alternator & regulator

[Chryco Psycho]

at idle the alt will often drop into discharge as it is not turning fast enough to keep the system at 14 v , this is normal , I would recommend you upgrade to the newer electronic voltage regulator if you still have the original points type reg

[mysil bergsprekken]

The lights pulsate when I am keeping a constant throttle of 3000rpm also. At steady driving the light intensity go up and down.
Is it the voltage regulator that is "regulating" this? And yes, I have the original single point distributor.

[64dartgt]

I have the same problem.  Noticed it friday and I was doing 70mph.  I am thinking it is time for a new voltage regulator.

[flyinlow]

Check the regulator to firewall ground . Clean and tight? Guys paint their car but can't bring themselves to remove the paint on the firewall so the regulator has a poor ground. You may still have a bad regulator but this cost little to check.

[68neverlate]

Could it be related to this??     

"Factory headlight switches have fast acting circuit breakers to reset the lights in a fast flashing manner  if there is a short in the headlight circuit to prevent total loss of lighting."

[John_Kunkel]

Run the headlight power through relays instead of through the bulkhead connector.

[resq302]

damn John!  Nice laid out diagram!

[flyinlow]

Could it be related to this??     

"Factory headlight switches have fast acting circuit breakers to reset the lights in a fast flashing manner  if there is a short in the headlight circuit to prevent total loss of lighting."

Are all the lights pulsating or just the headlights?

[shorty442]

John Kunkel

Any recommended relays for handling the load and ease of installation?

[flyinlow]

damn John!  Nice laid out diagram!

I agree. The only thing I would suggest is using separate fuses for each relay. If  the low beams short and blow the fuse you could still switch to the high beams.

[John_Kunkel]

John Kunkel

Any recommended relays for handling the load and ease of installation?

Any 30-amp ISO relay will work.

http://www.summitracing.com/parts/VIA-80237/

[shorty442]

Thanks John - it actually makes sense!

[mysil bergsprekken]

Are all the lights pulsating or just the headlights?
[/quote]

I am not sure if it is all the lights because I have no working lights in the dash (This is related to a lightbulb issue, so that is another deal, not related to this) And it is pretty difficult to look at the rear lights while driving obviously.

But the lights doesn't go all the way off and then back on again. It is just the strength and the light that is varying. Actually in a 1-2-3 and 1-2-3 beat!! He he. how is that for an explanation! (you get the idea).

[flyinlow]

[quote author=mysil bergsprekken link=topic=But the lights doesn't go all the way off and then back on again. It is just the strength and the light that is varying. Actually in a 1-2-3 and 1-2-3 beat!! He he. how is that for an explanation! (you get the idea).
[/quote]

Probably the regulator. cha-cha -cha

[Nacho-RT74]

probably alt brushes are worn

[mysil bergsprekken]

probably alt brushes are worn

So it can also be the alternator brushes. I know that those haven't been changed in a while. I am waiting for a new set.
But isn't the rotation inside the alternator so high that wheather the brushes are touching or not, it is rather of a yes or no question. I've had brushes get worn out on a Volkswagen I had, an then it just stopped charging the battery.
What about rebuilding the alternator? (aren't there kits for that?, not sure what they contain though, brushes, condenser etc...)

[mysil bergsprekken]

Could it be related to this??     

"Factory headlight switches have fast acting circuit breakers to reset the lights in a fast flashing manner  if there is a short in the headlight circuit to prevent total loss of lighting."

Not sure I quite understood this.

And "John Kunkel", would I have to install (if i read the nice diagram correctly) two relays, one on each circuit? And wouldn't this make for a non original setup. Thanks for your reply.

[Nacho-RT74]

probably alt brushes are worn

So it can also be the alternator brushes. I know that those haven't been changed in a while. I am waiting for a new set.
But isn't the rotation inside the alternator so high that wheather the brushes are touching or not, it is rather of a yes or no question. I've had brushes get worn out on a Volkswagen I had, an then it just stopped charging the battery.
What about rebuilding the alternator? (aren't there kits for that?, not sure what they contain though, brushes, condenser etc...)

yeap there are kits, but begin just for brushes AND isolators. When the bushes begin to work bad, usually causes heats on it and melt the isolator housing.

[flyinlow]

The reason I asked if all the lights were pulsating was to help narrow down whether you had a charging system problem or a headlight wiring problem.

If your charging system voltage is fluctuating , all the cars lights will vary. So would the wipors ,blower and horn, if you kept blowing it that long. Easiest to notice with the lights and all the lights would vary. This could be caused by the regulator,a regulator with a bad ground, worn alternator brushes, bad alternator or a wiring problem.

If you have a short circuit in the headlight wiring, the headlights can pulse being protected buy a quick reseting circuit breaker built into the headlight switch. This is done so that if you have a short develop while driving at night, you do not go totally dark. The parking lights ,sidemarkers, and dash lights are protected by a fuse. they are powered by a separate curcuit controled by the same headlight switch. A headlight circuit short would not make the parking lights vary. The dimmer switch is a common cause of problems. It lives in a dirty, sometimes damp environment. and is in the headlight circuit.

[68neverlate]

Could it be related to this??     

"Factory headlight switches have fast acting circuit breakers to reset the lights in a fast flashing manner  if there is a short in the headlight circuit to prevent total loss of lighting."

Not sure I quite understood this.

flyinlow explained this very well... to diagnose properly, it's necessary to determine if the pulsating is happening on everything or just the headlights.

And "John Kunkel", would I have to install (if i read the nice diagram correctly) two relays, one on each circuit? And wouldn't this make for a non original setup. Thanks for your reply.

John's suggestion is not an original setup, but that's the whole point, the factory wiring design for the headlight circuit is weak at best (the total current used to run the headlights also travels through the switch).  I also like to keep my car original... but I make exceptions when it comes to safety.  John's suggestion significantly reduces electrical wire overheating and fire risks of the factory design.  This is one thing you'll want to stray from original to keep your car safe... especially if you're upgrading your headlights to brighter halogens etc..   

I'm in the middle of making these modification to my car right now (thanks for the diagram John).  That along with the wiring mods that call for a direct run from the alternator through the bulkhead (bypassing the bulkhead connector) and then bypassing the ammeter in the dash that Nacho summarized on this site.  I would recommend you consider those as well...     

[ramairthree]

I have done the relays also.

Really works great.

If a driver great.

If you want all orginal appearance, not so great.

[Nacho-RT74]

you can make original appearence if hidden relays inside the cab... once wring is upgraded. The relays can be sourced from ammeter stud and stock wires and plugs from inside can handle EASILY the halogen headlights load ( is not SO BIG to not drive it ). Relays in fact are already made on same kind of prongs like our cars have.

[GreenMachine]

Here's my old post on the subject

http://www.dodgecharger.com/forum/index.php/topic,7921.msg94939.html#msg94939

I think Chryco is right on my post about it being a bad connection or corrosion. I never found my problem before I tore the car down for resto, but I did rule out the alternator and the voltage regulator.

[Paul G]

Let me try to remember this problem, it's been years ago. I believe the alternator has diodes in it. Diodes change the A/C current in the alternator to DC battery current. If a diode fails it will be passing a chopped DC in to the electrical system. If the pulsing lights varies with engine speed it is the diodes in the alternator. That is if I remember this problem correctly.

[mysil bergsprekken]

Thanks Paul. Yeah the diodes might have something to do with it. But remember in my case the lights pulsate at an even throttle. So they dont pulsate more at 5k rmp than they do on 2,5k rpms.