Flickering or pulstating Headlights

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Ok just want to make sure I got this straight. (to many blues wires, im getting a little confused)

Superchargeddrt's diagram looks like I should tap into the blue wire (after the ballast) on its way to the field connection on the alt.

67Dart273, sounds like what you're saying is cut the blue w/white tracer right after it comes through the bulkhead, use the bulk head end to trigger the relay, and connect the relay output to the other end of the blue /white that I cut, then it will go to the ballast and on to the field connection on the alt.

So, which is right, or will it work either way.
 
The wire coming out of the bulkhead connector is the source coming FROM the key. So you want to "unload that" to take load off the switch. So break it there before it branches off. Use that bulkhead wire to key your relay, and use the "other end" out in the engine bay as the load

You can pull power off the start relay "big stud" put a big fuse or 20A or so breaker in that line.

Another thing you can do is to run the relay coil ground to a little switch in the car and it can act as anti--theft
 
67Dart273 said:
The wire coming out of the bulkhead connector is the source coming FROM the key. So you want to "unload that" to take load off the switch. So break it there before it branches off. Use that bulkhead wire to key your relay, and use the "other end" out in the engine bay as the load

You can pull power off the start relay "big stud" put a big fuse or 20A or so breaker in that line.

Another thing you can do is to run the relay coil ground to a little switch in the car and it can act as anti--theft
Click to expand...

Thanks much, good idea on the relay ground too.
 
Update: Big thanks to 67Dart273, and Superchargeddrt.

This fix worked perfectly, while I was at it I replaced some wires completely, new connectors everywhere, crimped, then soldered and covered with heat shrink tubing.

Now, with the car off, but key in "run" position. I can probe the Ing wire right before the regulator and I get .20v much better that the .95v I was getting before.

Totally fixed the flickering lights, and the corresponding squeek from the alt every time they flickered.
Lights are nice and bright and steady.

Checking charging rate at the battery with car running at idle still fluctuates a little but way better 13.9 - 14.45 Was charging over 15 before.

Thanks again guys.
If I can get the video off my phone I'll post the difference in the lights.
 
My son's 70 was hitting 15.25. After cleaning bulkhead connections and grounds I decided to install a relay. Now I have headlight and amp gauge pulsating. What the heck happened?
 
Glad to help. 67Dart273 is a wealth of knowledge on these cars. I have a electronics background so that's how I figured out how to cure my flickering problem. I am just finishing up a ton of wiring work on my Dart. I am trying to conceal a lot of my under hood wiring.
 
340doc said:
My son's 70 was hitting 15.25. After cleaning bulkhead connections and grounds I decided to install a relay. Now I have headlight and amp gauge pulsating. What the heck happened?
Click to expand...
Good job! It's such a cheap fix too. A couple of hours and about $10.00.
 
Hey guys I didn't want to start a whole new thread since I'm having similar issues to here. My '70 Duster has flickering lights and voltage at all speeds, idle or above. I bypassed the ammeter and replaced the fusible link while I was at it but that was a few years ago; also installed Auto Meter gauges with a voltmeter. When the engine is running above idle the voltage will pulsate between about 14-15 and I can see my dash lights and headlights flickering with it. I'm thinking about trying the relay mod for the ignition switch but could it be something else? This issue wasn't noticeable the last time I was driving the car 2 years ago but since it has sat and I put another engine in this problem has popped up. I know the wiring from the alternator is still the old factory stuff could that be a source of the problem? Basically should I just try putting in new wire first or will that probably not fix the fluctuating voltage issue?
 
Could also be a regulator or the regulator ground (scrape the paint on the firewall where the bolts go through). Could also be the alternator brushes. Try disconnecting the wire on the alternator and ground the brush connection. This will make the alternator go to full charge. Try revving the engine and see if it still flickers. If it does then I would suspect the alternator. If it doesn't then I would checked (as mentioned above) the ground on the regulator and possibly the regulator itself. If all else fails try jumping battery voltage to the "I" (ignition) terminal on the regulator. This is a test that mimics the relay mod. If it works then install the relay. I am here to help if you have questions.
 
superchargeddrt said:
Could also be a regulator or the regulator ground (scrape the paint on the firewall where the bolts go through). Could also be the alternator brushes. Try disconnecting the wire on the alternator and ground the brush connection. This will make the alternator go to full charge. Try revving the engine and see if it still flickers. If it does then I would suspect the alternator. If it doesn't then I would checked (as mentioned above) the ground on the regulator and possibly the regulator itself. If all else fails try jumping battery voltage to the "I" (ignition) terminal on the regulator. This is a test that mimics the relay mod. If it works then install the relay. I am here to help if you have questions.
Click to expand...

By brush connection on the alt do you mean one of the field wires or the main wire? lol I'm not the best with electrical stuff. I'll try scraping the paint under the regulator first, there's probably corrosion underneath it's been there for a while. Come to think of it I did have a pulsating issue before because I replaced the regulator a few years ago at least and it did nothing. And the alternator is a parts-store reman so... yeaa
 
OH forgot to mention the battery is an old hunk o' junk might that cause these issues also?
 
I mean the field connection that goes to the regulator. One field will be connected to the battery and one will be connected to the regulator field (F) connection. Remove the wire (green wire) that goes to the field, verify that you have removed the correct wire by measuring the voltage at the other field connection with the Ignition on. When you ground the field connection that you removed the wire from the alternator should charge at full charge. Check to make sure that the lights are not flickering when you rev the engine. If they are still flickering then I would look at the Ignition switch or bulkhead connections (if you are sure that the regulator has a good ground). By the way do not leave the alternator at full charge for a long time.
 
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MopaR&D said:
OH forgot to mention the battery is an old hunk o' junk might that cause these issues also?
Click to expand...

Step one of any electrical diagnostic is to make sure the battery is in tip-top condition.
 
The battery is the only thing I've changed in the electrical system since the last time it was running and I'm pretty sure it has a dead cell, last winter I took it out of my Jeep to put in a new one since it was losing a lot of charge overnight in cold outside temps... I've been keeping it on a battery tender when the Duster is sitting in my garage and it starts up fine but I know the charge capacity of the battery is really low. I guess I'll go ahead and replace it first before other troubleshooting since I need a new one anyway.
 
340doc said:
Deka is a good battery also, made in USA
Click to expand...

IIRC either that brand is now Duracell or at least Batteries Plus sells those and East Penn/Deka as well. I put a Duracell Ultra in my Jeep, best battery I've had so far just from overall cranking power esp. when the weather is really cold. Even Interstates are made by JC now it sucks, and one of those is only $10-20 cheaper than a Deka or Duracell anyway you just have to know where to look.
 
I've had good luck with Sears Diehards. The one in my car (trunk mounted so size was not an issue) is the biggest baddest Platinum they made. I bought it about 5 years ago and have had zero issues. The one before it lasted 14 years believe it or not and it was still cranking the engine fine, it's just I was getting nervous. I keep my batteries on a tender at all times so that's probably why they are lasting, just don't know what I'll buy next time as Diehards are no longer an option. I like the fact that Deka is made in the USA, maybe I'll go there.
 
MopaR&D said:
When the engine is running above idle the voltage will pulsate between about 14-15 and I can see my dash lights and headlights flickering with it
Click to expand...
Could be ripple voltage or a regulation issue.
Also possibly a poor connection or loose plate etc.

superchargeddrt said:
Try revving the engine and see if it still flickers. If it does then I would suspect the alternator.
Click to expand...
This is a good check.
Also, what is the voltage at idle? and is it steady?
How 'bout with lights on?

MopaR&D said:
By brush connection on the alt do you mean one of the field wires or the main wire?
Click to expand...
Yes and no.
You can see what the brushes in post 15: Alternator repair, a little show and tell.
In the photo below you can see where the brushes come through.
upload_2019-3-20_21-50-52-png-png.png

(The yellow arrow points to the output stud. If its loose it needs to be snugged up from the inside.)
The two copper rings on the rotor is what the brushes contact.
upload_2019-3-18_0-30-28-png-png.png


When electricty flows through the rotor windings, it creates a magnetic field. That's why the brush connections are called field terminals.
 
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Mattax said:
Could be ripple voltage or a regulation issue.
Also possibly a poor connection or loose plate etc.

This is a good check.
Also, what is the voltage at idle? and is it steady?
How 'bout with lights on?


Yes and no.
You can see what the brushes in post 15: Alternator repair, a little show and tell.
In the photo below you can see where the brushes come through.
View attachment 1715319078
(The yellow arrow points to the output stud. If its loose it needs to be snugged up from the inside.)
The two copper rings on the rotor is what the brushes contact.
View attachment 1715319079

When electricty flows through the rotor windings, it creates a magnetic field. That's why the brush connections are called field terminals.
Click to expand...

Thanks for the link I read through your write-up, still not understanding fully what all the internal parts do so I'm gonna read my 1970 Plymouth FSM about it. I doubt the alternator is in that bad of shape it's only a few years old but it is a reman'd unit from O'Reillys. Also no the voltage is not steady at idle, it never has been... only when it's revved above 1300-1500ish RPM does it start to charge steadily (but the voltage still fluctuates). This is with the headlights off too.

This battery is toast btw I went yesterday to start the car and had to crank it a bunch to fill the carb back up after taking it apart, I couldn't have cranked it more than 15 seconds total before I heard the starter (which is a modern mini-starter even) slowing down and the voltage went well below 12 on the gauge which was too low for my Mallory ignition box to energize and fire up. Annoying!
 
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