Check and clean as needed all of your grounds, the battery is a chemical based storage devise that makes the voltage that the vechicle runs on. The current flow from all batteries flows out the negative terminals into the system and returns through the positive side of the battery
If the grounds are not good it may lead to overcharging

So what's the solution?? What can be causing that??
Bad ground? Bad cable?

ok, lets start the trouble shooting.
with the van off
positive side of the battery to negative side of the battery reading=
with the key in the run position but the engine off

the ballast resistor should have 2 connectors on it.
what is the highest voltage reading you get using the battery negative and the ballast as the postive?
you can also unplug the vr and check the pin with voltage using the case as ground when it is bolted up to the body, what voltage do you get there?

if either of this is different than your first reading at the battery, you need to start checking a few more things.
does the voltage at the vr change if you use the battery ground instead of the case as ground?
if not then you have to start chasing the positive side back.
the positive passes through the bulkhead connector 3 times.
you can bypass this temporarily to see if your problem goes away by running a wire directly from the pos of the battery to the highest voltage side of the ballast resistor.
this will back feed the system with battery voltage directly so it isn't passing through the bulkhead.

start the van and check charging again with the bypass installed.
if that works, then it is a bad connection in the bulkhead that needs to be cleaned or replaced.
you will have to follow the line or check the wiring diagram to see which ones need to be checked.

I tried in the past to pull the wires out of the bulkhead connector to clean them with no success
! Not sure if I just gave up after a few minutes but I may need to make a tool or something because those connections are very solid as far as I remember!
I live in Arizona and we don't have that type of sand where I live! It's more of a silty clay not beach sand like the stuff from the vr!!!! I thought that was kinda weird! Maybe it's from when I lived in California? Or most likely from driving the I40??? The majority of the miles on it are from driving either on the 101 in Cali or I40 in Arizona... Whatever the case it was an interesting find and surprised if the vr is still working properly, which I'm still not sure of! I wouldn't be surprised if more than one thing is wrong with it though! Last time something happened the driveshaft fell off at the diff and the distributor broke at the exact same time!
Anyway, I'll get out there and perform those tests and brb!

This might help. https://www.youtube.com/watch?v=vEL-99w5HRU

https://mymopar.com/wiring/
they have 79 truck there so it should work.

Also, maybe check the wires at the ignition switch plug at the base of the column and under the dash. Sometimes the plug and the wires melt and can cause issues. That was what caused my overcharging issue. Blue wire grounding under the dash harness. Mine was on a car not a truck though.

I think I'm getting closer to resolving this issue! At least I've figured out that bypassing the bulkhead fixes the issue!....
I'm about to check under the dash like you said!

the bypass shows the vr is working correctly and is grounded correctly.
the issue is wiring somewhere else. you will have to track the wire voltage from the ballast back to the bulkhead through the bulkhead, into the ignition switch, back out of the bulkhead etc till you find battery voltage and then go back and start cleaning it up till you see battery voltage.

or wire in a relay lol.

A relay is an option.
I use it for my old car and have done the mod a few times.
I laugh because it is the lazy way out. instead of taking the time to find the actual issue, I just bypass it permanently.
relay has 5 connections.
you have to read the relay to see how it is set up.
but basically you have the original power source. the one that reads like 10 volts from the wiring diagram that goes to that big splice of everything in the engine compartment.
I cut that line before the splice and make that the voltage that closes the relay.
other end of the circuit that closes the relay is just any ground. I usually wire it back to the battery.
The second circuit is power from the battery to the splice end that is hanging free now.
so when you hit the key, it gives power to the relay, closes the circuit and power from the battery goes to that giant splice powering the ballast, VR and alt, with full battery power instead of the 10 volts you had before.
I would get one that is waterproof but isn't 100 percent necessary as long as you hang it somewhere slightly protected behind the engine or air cleaner. not sure on a van.
there are some pretty cheap ones out there, but junk yarding that part is probably cheapest. you can probably get one for under 5 bucks at the parts store for a generic one.

Your issue is somewhere between the two ends of the bypass wire Likely a connection. and IMO 14.9 is still too high.
if not previously mentioned the Ammeter terminal nuts are notorious for coming loose. DO Disconnect the battery while checking them

Don't the 79s have a shunt? I know nothing of B vans though.

I don't know either, that's the first time I've heard of a shunt!

Well, I've been driving the van for the past couple of days with no issues... Yesterday the wipers didn't work when I drove to work in the morning but they started working on the way home!
The voltage has been holding steady between 14.5 to 15 volts! I had mentioned before that having the blower on and lights was bringing the voltage down to 10.5!!! With that bypass in, the voltage has been steady at 14.5 volts! The voltage did drop for a bit at idle with the blower and lights but went back up in drive.... Maybe it has nothing to do with the overcharging problem but thought I'd mention it anyway...
I'll be back in a few days to post my findings in the wiring!

The top notch help and knowledge provided in this post is what's missing in the Facebook groups. The group etiquette on FB is NOT to do a search to see if the topic has already been covered but rather post it. Then the replies generally recommend rapid fire parts cannon deployment- or "Buy a new vehicle." Moparts.com for the win here.

I haven't had time to get into the wiring until today!! I don't have much of an update...
Honestly I'm extremely confused with the circuitry in the van regardless of how simple it is! Electrical is not my strong suit!!! I really don't know what to check for!
Correct me if I'm wrong but from what I understand the overcharging is caused by lowVOLTAGE to the VR and the VR is increasing the voltage to compensate? So I have to follow the power wires that go into the VR back towards the battery? It could be a bad connection somewhere or maybe a bad component?? Could it be the coil? Electronic control unit? Starter relay? What am I looking for exactly?? Should I follow the power cables/wire from the battery instead??? Am I supposed to be checking for the same voltage as the battery???
I unwrapped the whole harness in the engine bay so I could get a better look!

it is not likely to be a component.
it will be a connection.
that wire goes to the giant splice on the wiring diagram, then into the bulkhead connector, which is the most likely problem.
then it goes inside to the ignition switch, not sure if it is column or dash mounted. column mounted means another connector at the base of the steering column.
the ignition switch.
then back to the amp meter
then back through the bulkhead connector which could be the problem too, or combination of in and out.
then to either another common hot or to the battery.
you will also need to validate the grounds give you the same voltage. using the battery neg post and vr body. which you did earlier so you should be good. but just be careful using whatever is closest as a ground when you are inside vs in the engine compartment.
and you will have to do this with the key in the run position for power.
careful not to zap anything.
when you split the bulkhead connector you will probably see the corrosion.

that is a nasty splice.
continuity won't be the issue. it will be resistance causing the voltage drop.
but it sounds like it is past that splice anyway.
you probably don't have the extra line in that splice, but the old school way was to put ring connectors on them and put it on the big cable side of the starter relay. but I guess leave it alone if it ain't broke.

in the second picture on the R side I note several corroded male terminals. Those should all be cleaned as well as the others.
There's a couple that are a bit "hazy" but aren't corroded... They look much dirtier in the picture but are not that bad or preventing good current! There's only one connector there that's corroded! It's green and you can clearly see it in the picture. That connector goes to the 'transmission backup lamp switch'. The other two 'hazy' male terminals are for the 'high beam foot dimmer switch' and 'hazard warning flasher'... I doubt they have anything to do with the overcharging issue... Despite what they look like in the picture or in person they make good contact! Regardless, I didn't take the time on those terminals because they're not associated with the issue... At least I don't think they are!

Quote

I checked the voltage of the wire in the bulkhead running from the splice with the key ON and it reads 11.3v(firewall side) while the battery reads 12.6v... The voltage of the same wire at the bulkhead on the inside with the key ON reads the same (11.3v)!

the above statement is not clear to me ? I'm assuming this is with the bulkhead plugged together?
I am also assuming this wire is coming from the battery towards the splice
What is the V at the splice itself ?
if it is also 11.3 work back towards to battery.
Your statement indicates a 1.3V drop which is HUGE unless there is a draw pulling the V down or a bad connection not allowing the current to pass thereby causing the V drop.
Yes, with the bulkhead assembled... As instructed I followed the power wires from the VR and they run into the splice! Out of the 8 wires in the splice only one runs directly into the bulkhead and that's the one I'm referring to(J10A-14RE in the diagram)... From the splice directly to the bulkhead not the battery... That wire runs through the bulkhead into the ignition switch harness where it goes directly to the ignition and is identified as the 'ignition' circuit but it also splits off at the connector and goes down to the number 5 fuse of the fuse block and keeps going into the instrument cluster.
I checked the voltage of that circuit on both sides of the bulkhead connector and the voltage is the same on each side which to me indicates the connection in the bulkhead is making good contact. If it wasn't making good contact one side would have a different voltage right? Could it be something in the cluster drawing voltage??? Could this be the issue??
I hope that clears it up!



Run a jumper across the two connections and see what the voltage does. The jumper can run from the splice to where ever the firewall side wire goes. If it goes multiple places the one closest to the BH would be best.
DO monitor the battery voltage while doing these tests. [quote]

I agree, voltage the same on both sides of the connector means it isn't that connector.
it could be the ignition switch, as you noted due to the voltage drop there.
I would see if the switch has any resistance between the terminals disconnected from power.
you also might pull the neutral safety from the starter relay and test the voltage in start and see if that is down too.

Watch video 1 VIDEO 1

pay particular attention around 4-6 minutes where he demonstrates little resistance but that is with no load and the commentary that follows.

video #2 VIDEO 2

this is a very simplified example to locate voltage drops. There are more videos on you tube

i would start at the battery. Using you're schematic follow the Voltage from the battery checking EACH connection along the way.

the + battery cable carries the V to the Starter motor lug. Sometimes a separate wire off the battery carries the ACC /RUN/lights etc to the starter relay. other cases the wire comes from the starter motor lug .

There is normally a fusible link between the relay and bulkhead connector.

out of the bulkhead to one side of the ammeter

out the other side to your Splice.
out of the splice to the various components some of which are live all the time (lights) others through the ignition switch. MOST but not all will go through the fuse box.
This is difficult at best but Tenacity will win.

I alos wanted to comment on the bulkhead connections. on the male tabs some are visibly making connection evidenced by the female terminal scrape marks. others are not showing those marks that I could see

I alos wanted to comment on the bulkhead connections. on the male tabs some are visibly making connection evidenced by the female terminal scrape marks. others are not showing those marks that I could see

I agree, voltage the same on both sides of the connector means it isn't that connector.
it could be the ignition switch, as you noted due to the voltage drop there.
I would see if the switch has any resistance between the terminals disconnected from power.
you also might pull the neutral safety from the starter relay and test the voltage in start and see if that is down too.

sorry, that is actually a few things at once.

pull the neutral safety wire from the relay to prevent the starter from trying to start the van.

the switch has a plug on it, so you can do 1 of 2 things.
you should be able to stick the probe in the back of it, but if you can't, then pull the plug slightly so you can get a probe between the switch and the plug.
so the test will be to see between a ground not on the switch and the ign 1, ign 2, and the other post that goes out what the power drop is if any before you turn the key and after.
so I don't remember the posts that goes out to the bulk head.
but you have start and run on the ignition switch.
both have power going into them.
when you turn the key to start, and hold it, you should be able to test the power out of the switch. same when you leave it in run.

having the neutral safety disconnected prevents you from hanging the starter on the whole time.