Charging voltage low.

[76mopar]

I've been fighting electrical gremlins from time to time on my '76 Charger SE. It started about 5 years ago when it decided to leave me stranded in Virginia on my way to Bristol for a car show. Luckily I found a motel across from a Napa store that I was able to somewhat fix the car to get me home had to abandoned the show.
The problem is that the charging system goes out. At that time I changed the Alternator, Voltage regulator and even the battery (Needed a new one to have enough juice to get me home). But the system never charged. After I chased wires down I found the Field and Load Relay on the firewall must have went bad. Couldn't find a new one at any parts stores had to get one from a junkyard in Ohio. I even changed the regulator in the dash to be safe. Back working good but still leery of the cars dependability now. Chased all wires none were burnt or cut.
Fast forward a few years and now the Alternator went out again. So this time I just went with a one wire deal to by pass that relay. Seemed to work good but that alternator took a crap about a year later. Now this car doesn't get drove much in the mean time just sits in the garage on a battery tender to keep it fully charged. So last year I get a real Chrysler alternator and put everything back and all seems to be good now........
Until Last month when I started to notice that the Charging voltage is not where it should be running down the road its around 12.8 Volts. And when I use the blinkers the radio goes on and off as the blinkers blink, last week I found that when I use the wipers the radio goes on and off also. I've got a car show I'm wanting to go to in Indiana and need to get this figured out. The alternator is good cause when I ground the green wire it jumps in voltage to the battery. I'm gonna change voltage regulators tonight to see if that fixes the charging problem
Car is bone stock wiring has not been hacked on.
So my question to you is has anyone had this kind of problem before? Do you think the Field and Load Relay has gone to crap again? I'm at a loss. I would like to get this car to be dependable again. I love driving it. Funny thing is that the 2 '77 Doba's and the '77 Charger SE I have don't have the field and load relay so that makes this puzzle even harder. Can I bypass the relay, if so how?
I will post a picture of the relay tonight. I will post a picture of the wiring diagram also.

Sorry for the long drawn out post. Hopefully it makes sense.
Wiring diagram: http://www.auto-wiring-diagram.com/...l-wiring-diagram-of-1976-chrysler-cordoba.jpg

 

[76mopar]

Update: changed voltage regulator and now its at 13.3 volts. Doesn't trip the radio when I use the wipers or the right turn signal. It trips it for the left just at first. Been thinking there might be a chaffed wire in the column.
So I guess for the monument it seems to be fixed. Which I'm still not liking the 13.3 volts. I thought it was suppose to be around 14.4 but that might be for the newer cars.

 

[Shorthorse]

Seems like lots of unrelated things affecting other things. Check all your grounds. I don't know whether the 76 uses a ground strap under the dash or grounds via the mounting bracket but definitely check that. Also, make sure your voltage regulator housing is well grounded.

 

[bigmanjbmopar]

Alternator grounded?

 

[76mopar]

I made sure the regulator was grounded good when I put the new one on. I guess I need to go over and check the rest of the grounds and make sure the are truly touching metal. Ok dumb question how would I make sure the alternator is grounded properly?

 

[bigmanjbmopar]

The outer case grounds to the block via the mounting bracket. You can also add a ground strap to the outer case and ground it to the body or block to make sure it is getting a good ground. An example of an external ground is on the one wire alts, they come with a terminal for a ground strap.

 

[76mopar]

Ok thanks for the info

 

[440roadrunner]

Let's talk generalities...................

I didn't look at your car's diagram (shop manual) and the link you posted to a diagram erupts to "something else" Don't know what all that even is.

The VR MUST be grounded to "same as battery." MUST. So it has to be "clean" and tight--scrape the bolt holes, etc, and use star washers

Suspect the VR connector is bad / intermittent. Might try replacing it if you can't find anything. "Work" it in / out several times to scrub the terminals, and pull it off and examine with a strong lamp for corrosion.

Test the alternator for "full" output. BECAUSE you are getting low charging voltage, I would do this:

Pull the green off at the alternator, and ground it. With a meter monitoring the battery, and the lights on, CAREFULLY bring up charging voltage to 14V with the idle screw and hold it steady. Now move your meter over to the blue field connector on the alternator. You should have MINIMUM of 13V there at the connector. This shows that part of the circuit supplying field power is OK

With the thing still fast idling as above, move your meter to the alternator output stud. Then quickly re-check battery voltage. The two readings should be within 1/2 volt. This shows that the alternator output path / wire (charging wire) does not have a great big voltage drop or bad connection on the road to the battery.

Now with that much done, you need to figure how to "tap into" the VR IGN terminal (blue). Might have to "pin" a wire. "Normalize" the wiring, againg leaving the engine running fast, lights on.

Check battery voltage. Ideally, it should be 13.5--14.5, and optimal 13.8--14.2. WARM. The VR is "temperature corrected." But what EVER that battery voltage is, now move the meter over to the VR IGN line and compare. It should be very very close to the same voltage.

In very rare cases, it's possible for a battery to cause this. Could be a bad VR, but you've already tried at least one?

I would "bet" on low voltage supply to the field or to the VR. Could very well be related to the "field loads" circuit. Those are a mess, as far's I'm concerned.

Do you have the 100+ amp unit? (big frame alternator?) I used to run one of those in my old Landcruiser (340) with a winch