Howdy,
Took my stang out last night and it got dark and turned on the lights. I noticed that my dash lights and driving lights were pulsating/flickering. They do not go out but a plusating dimming. Any ideas or what to check would be greatly appreciated!
Thx, Walt

 

Chances are good that switching to a quality electronic voltage regulator will solve the problem.

 

Pretty common in a 45 year old car. The 38 amp alternator has trouble keeping up with all the power requirements, plus the lights get power through the dash harness, through the usually weak/old headlight switch, out to the lights.

Most people install a relay system that pulls headlight power directly from the battery, bypassing the wiring harness, and then uses the old wiring as a switch signal to trigger a relay.

http://www.midnightdsigns.com/james/headlights.htm

 

Do both of the previous suggestions

 

I fixed the problem with a $15 off the shelf Electronic Regulator (under the hood). They say if you want you can remove the cover off a stock looking one and put it on the new one if you want the original appearance.

This was probably the easiest, fastest, cheapest repair I have done to my baby.

 

I don't really have anything to add to whats been said other than I agree with whats been said.

 

Alternator in my opinion. The relay upgrade and headlight switch replacement will make your lights brighter as more voltage will be reaching them direct; however, chances are the flickering problem probably won't go away until you upgrade the alternator. I completely replaced my entire wiring harness with a Painless harness and replaced all my switches at the same time. Lights are MUCH brighter, but I still have a bit of flickering going on at idle. I'm going with a 3G upgrade myself. I've heard the one-wire setups are just as good, but that's a whole other debate.

 

A new alternator may help and may make the lights brighter. But I'll say it again: $15 bucks, 5 minutes, my problem was solved 100%.

 

Yea its def not the alternator. The alternator regardless should be giving out a constant 14.1v or similar and should not cause the headlights to pulsate unless the voltage regulator is bad.

Easy way to test your alternator would just be see how much voltage battery is getting with everything that you normally use on.

 

I'm willing to bet that if just about anyone with a stock alternator setup tested their voltage at idle with the lights on, they would get a reading of less than 14v. It's not always to do with the voltage regulator either. It depends sometimes on the capability of the alternator, which in stock form wasn't capable of much, especially after 40+ years. Sometimes it depends on the engine RPM, pulley size, condition of wiring, etc. Do a quick search on 3G conversions, or check out madelectrical.com. You'll find tons of info on folks who weren't getting a good charge out of their stock alternator, and it had nothing to do with the voltage regulator. The regulator can regulate all it wants, but if the alternator itself for whatever reason isn't capable of producing enough voltage at idle to run all the accessories, then you may need a better alternator.