1968 New Yorker 4Dr HT: Headlights dim with blinker and brake use

T. Aguryte

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While driving or stopped, whenever I used the blinkers or brakes, the headlights and dash lights would dim momentarily. The ammeter would show a slight discharge but never below center line.

At first I thought the voltage regulator was failing, so I switched-out the original with its solid state counterpart. Now while driving, the headlights and dash lights still dim momentarily but the ammeter shows a discharge below centerline. While stopped, everything remains dim and the ammeter shows a heavy discharge. Is the alternator going out? Or is there something else I'm missing?
 

CBODY67

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How "dim" are the headlights getting? A slight amount is somewhat normal, but not a lot.

Clean the battery post and cable end terminals with a wire brush cleaner. Then do a "charging system check" to see what's really happening.
 

furious70

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It's normal for these 50 yrs old cars and systems that are corroding and rotting. Even 25yrs ago we had cars with the base alternator dim at idle at night.
Check for resistance in the various circuits
 

413

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It is normal even when the 1961-1969 mopar car was new. Single field alternator and point style voltage regulator. The alternators don’t put out much until 1000-1200 RPM.

the 1970 dual field alternator and electronic voltage regulator was an improvement.

late model cars are charging 14+ volts at idle speeds.
 

watchfatha

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While driving or stopped, whenever I used the blinkers or brakes, the headlights and dash lights would dim momentarily. The ammeter would show a slight discharge but never below center line.

At first I thought the voltage regulator was failing, so I switched-out the original with its solid state counterpart. Now while driving, the headlights and dash lights still dim momentarily but the ammeter shows a discharge below centerline. While stopped, everything remains dim and the ammeter shows a heavy discharge. Is the alternator going out? Or is there something else I'm missing?
My 64 Imperial responds like that, my 66 Imperial does not. Something's different-but I don't know what.
 

fury fan

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@T. Aguryte
Just a quick flicker when you hit the brakes, right? Mine has been doing that for forever. Even after alternator and Vregulator upgrades (which those helped with the discharge).

If showing a heavy discharge at idle, though - there are some alternator upgrades you can do (somewhat inexpensive) + wiring connection cleanings.
But no harm to live with it if you don't drive much at night?
 

cbarge

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As mentioned, a typical normal characteristic of our old beloved Mopars.
But there is a solution..
Read...
Plug n play headlight harness upgrade
Also I strongly advise to do the underhood ammeter bypass.
Underhood Ammeter Bypass
These two upgrades alone will make your electrical system super reliable.
As a current owner of a 68 Chrysler among others..ask me how I know..lol
Hope this helps.

20221121_124224.jpg
 

T. Aguryte

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Oh man... thank you guys for all the replies. [Long story short: New voltage regulator was taken out and the old one put back in. I was looking for problems that didn't exist? And two mods are on the horizon.]

CBODY67, fury fan: Yeah, just a quick flicker with the old voltage regulator, even at idle. At idle with new one, though, I'd lose maybe 50% lamp brightness or to the point where I thought the car would die.

furious70, CBODY67: Both of you got me to think about other causes -- things I suppose I should have checked-out before posting. Battery posts, clamps, and wires ends were clean but the wires were kinda loose. No arcing though. So you saved me some future hassle there. And I pulled the bulkhead connectors and found that they're mint. Cool. Deoxed them anyway. Haven't checked voltage drop or AC leak from the alternator yet. I ran out of daylight today so will do that tomorrow.

watchfatha: With two cars behaving differently, you got me thinking that maybe the contact gap of the voltage reg. relay might be off; so I opend it up but everything was spot on.

And 413 got be wondering about what was happening at the battery. Before I started work, the battery read at 12.61 so even the new regulator had been doing its job, I guess. Battery with old regulator in and at idle was 12.7. At idle and with high beam lights, heater fan on high, radio and courtesy lights on, (forgot about wipers and cigarette lighters), the reading at the battery was 13.7 volts and ammeter showed charging. Don't think I can ask for anything more, huh?

cbarge: Had already ordered the parts for the ammeter bypass. They're in so will do that tomorrow, though I really like a functioing ammeter. (Maybe I'll rig an underdash bypass switch for the bypass? Uh, maybe. We'll see.) But I had never heard of controlling the headlights with relays. That's great! Top of my list. Some parts I have and the rest are on order.

Thanks again everybody.
 

FURYGT

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Keep in mind that the stock alternator for a non A/C car is a 38 amp & an A/C car is 45 amps. Nothing worry about. You can raise the idle a bit to see if that helps.
 
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