Voltage problem

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Vandal

Vandal

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Hello FABO community I’m having a problem that won’t go away so I was seeing if I can get someone input on this, my alt gauge his crazy when I press on the gas I have already changed my alternator twice and my VR twice once I changed them both the second time it stabilized and stayed in the middle even with high beams on and flooring it!! I’m fairly new to these cars, so I was reading around read a comment about disconnecting the VR and if it stabilizes that means the cables and alternator are good I did that and it did stabilize, so my question is, is it just these cheap VR’s?
 
WHAT year?

What car?

Did it ever work "correctly"

WHat modifications have you done



What are you trying to fix?

In stock form these cars "Charge Indicator" will move around alot. typically at a stoplight you might even see it below center. when the turn signal is on it will bounce around.

This is mostly normal.

The indicator is displaying the current NOT the voltage. at low RPM the typical ALT will not produce enough current to satisfy the loads ( lights, radio etc.)

There are other things that can be in play here as well, bad connections, miswired connections.

as For tests, first we need to understand what is the real issue is

Vandal said:
disconnecting the VR and if it stabilizes that means the cables and alternator are good I did that and it did stabilize
Click to expand...

if you disconnect the VR the alternator will not output anything you will be running on battery alone.
 
Sorry about that I have a 1970Dodge Dart Custom (the sedan) i got it just earlier this year and its fully stock it has the slant six in it and What I done so far is got the engine rebuilt bought new plugs new cables new distributor rotor and cap new alternator, And a new Vr so far
 
And also because of this my radio does turn off when I press on the gas
 
I seem to recall something about another thread that talked of radio turning off. was that you?

there are so many issues here.

you are going to have to start at the beginning and work through the problem.

do you have a voltmeter?

have you downloaded your car's Factory service manual?

go to ClassicCarWiring.com, spend the 20.00 and get your cars colored wiring diagram 11"x17" (https://www.classiccarwiring.com/1970-dodge-dart-non-rally-dash-color-wiring-diagram/) I assume you do not have the rally dash

@Mattax @67Dart273
 
The first thing you need is a VOLTMETER and some other electrical tools, such as a 12V test lamp and a few alligator clip jumper leads

Then you need a factory service manual........which you can download.......for free.......from MyMopar Some of the manuals over there came from the guys right here. Also while you are there, wander around that page a bit, download the aftermarket wiring diagram (2 pages) which are often not complete but somewhat easier to follow at times.

Also wander around over there and you might save the "basic" wiring diagram posted for the alternator / igntion.

Now, with the car running on fast idle to simulate low/ medium cruise RPM, measure charging voltage, and again with headlights and heater powered on, and then once again with RPM higher, to simulate highway high speed cruise.

If voltage is much above 14.5 you have a problem

THE NUMBER ONE cause of over-voltage problems in these old girls is a poor ground between VR and the battery, and voltage drop in the harness. That is, the VR does not see battery voltage, but rather something lower, and compensates by ramping up charge voltage

WHEN YOU GET a voltmeter post back and we'll step you through this

Also please attempt to use proper punctuation and sentences so we can actually read what you are typing
 
Thank you I’m going to try to get one as soon as possible.

I just want to add I just came back from the store with a replacement VR and it does seem to stabilize the alt gauge.

so new question. If my VR isn’t Screwed on tight to the frame would this cause problems?
 
YES and I mentioned that above. VR MUST be grounded to "same as battery" Scrape around the bolt holes and use star lock washers. IT is wise to add a ground cable from engine block to body

Not sure on a 6 where a good handy spot is, but a great body ground is to bolt the cable to one of the master cylinder mounting studs. Buy what is called a starter cable, "eyelet to eyelet" ends and they come different lengths

Like this

b2024-048_(1)_web.jpg
 
67Dart273 said:
YES and I mentioned that above. VR MUST be grounded to "same as battery" Scrape around the bolt holes and use star lock washers. IT is wise to add a ground cable from engine block to body

Not sure on a 6 where a good handy spot is, but a great body ground is to bolt the cable to one of the master cylinder mounting studs. Buy what is called a starter cable, "eyelet to eyelet" ends and they come different lengths

Like this

b2024-048_(1)_web.jpg
Click to expand...
Thank you so much for all the information I’m going to do that this weekend coming up, I got the star lock washers and got my VR grounded better and the ALT gauge isn’t going crazy anymore. Thank you!!
 
Also, 1970 probably has the older mechanical voltage regulator. Those are a large rectangular box with one terminal "FLD" w/ screw connection for the control wire (green?) going to the alternator. The later electronic Vreg's look much different, being flat with a triangular 2-wire connector. For the old type, you can buy a better electronic Vreg which has the same connectors for easy substitution, and will never need fussing with like the old ones. As 67Dart273 said, one electrical connection is to ground thru the case. The factory relied on a rusty sheet-metal screw, which was OK to meet the 3 year warranty. I ran a dedicated ground wire to the Vreg in all my cars. You see that today in most cars, along with many solid ground studs scattered around the car, since they found sheet-metal screws aren't reliable.
 
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