Interior lights pulsing???
 

I have a 65 K code coupe which has had this problem for a while. At idle, all of the interior lights including the dash and radio lights have a continuous bright/dim, bright/dim pulsing effect. Once driving at normal speed, this condition disapears. All of the interior wiring is still original but looks to be in very good shape with no splices. I have replaced the altenator, alternator harness and the engine to firewall ground strap which did not make a difference and I can't see anything else thats looks out of place. Any ideas??

Couple of Q's what is your idle speed and also are you sure the pulleys you are using are allowing full charge at what you are idleing at?

Mine does this too. I think it's the voltage regulator clicking off and on. Not sure though. It is annoying. Could possibly be fixed with an internal diode regulator (better amp supply, too). I haven't done this. Anyone else have ideas? Jon?

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'66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph
1/4 mi.

Thanks a lot for the responses. In anwswer to the first question, the car idles at 900 rpm and has the original larger (3 7/8" dia I think) steel alternator pulley which i swapped onto the new alternator which is a 63 amp unit. The water pump and crank pulley are also the originals.

If you have a smaller diameter pulley for the altenator laying around I would try it it will spin the altenator a little faster you might be right at the point in the alternator rpm wise that it is turning off and on at idle...On mine I have it idleed at 1000 and I switched to serpintine puleys so my crank is now a larger pulley than before and the alternator is a smaller one and I don't have a charging problem at idle even with my headlights one and I run and electric water pump,2 electric fans and an electric fuel pump all on the same 60 amp alt.ya'll are running.

Check all your electrical grounds and make sure they are solid with no rust or paint under them.

I had a similar problem a few years ago, my stereo and lights would flicker at idle and especially when my turn signal was on. After checking/cleaning all the electrical grounds the problem disapeared.

Hope this helps.

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1968 Fuel Injected Mustang Coupe

I haven't run into this problem. But I ran without interior lights for awhile due to corrosion on the dimmer resistor in my head light switch.

-JON

Just a quick thanks to everyone for the responses. I am going to check out all of the grounds and also throw on a meter and check the charging output of the alt at idle this weekend before putting the ol' horse up for the winter (very sad!) on Sunday.

Jaydee,

I see that everyone else has probably helped you enough but I just wanted to chime in. I had the exact same problem on my 66. The interior lights and the headlights would pulse depending on engine idle. I was having some other probs at the time so I ended up replacing the alternator (higher amp model) the voltage regulator and checked, cleaned, and rewrapped all the connections I could find - all at the same time. The pulsing hasn't been back since, but now I don't know which of the three "fixes" solved my problem. If you still have troubles it's always good to start with the cheap stuff like the regulator. Hope you figure it out.

Stefan

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66 Tahoe Turquoise Coupe
Laser Red 96GT Ragtop
Both are slow but easy on the eyes!

I really don't have any thing to add to this, as the others have covered it pretty well.

I would definately try to freshen up all the connections that you can get to, and for sure work on the grounds, people always seem to ignore the grounds.

I took Stefan's approach...I stepped up to a larger alt. and cleaned all the connections. I had the same problem he did....the entire electrical system pulsed, including the headlights. I bet yours do too, as well as having all the lights dim in general while at idle. Pretty common in a car this old I guess.



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66 GT Fastback 5.0, 5-speed, cable clutch, JBA's, 3.40 gears, EFI coming soon?