Low charge to no charge issue pulling hair out

-
The charger voltages may be confusing. You cannot charge a battery at 12 something. Chargers, just like automotive alternators, MUST charge at least at 14V nominal, depending on temp and whether the batt is lead acid or something else. Even a "float" charger is around 13.5 and that would be 24/7

So, charger disconnected, surface charge gone, a battery should be nominal 12.6. If the charger is "really smart" and can resolve that, then it might show that. I doubt most do.
 
1732906224184.png


Cleaned this up a bit.
The fact there is a drop at the fuse box when everything should be off tells us something must be drawing power.
Pressure (voltage) only drops when current runs through resistance. No current flowing, then there is no resistance.
So something is on. It might only be the dome light. It could be a radio, but since the Alt is a the same voltage as the bat, I don't think its a bad diode in the alternator. Rather its something that is on a fused circuit.


I tried helping someo ne else on FABO with an e-body a few years ago and he too seemed to have an issue like this. The fusebox is different than a-body boxes and without being there I couldn't help him track it down.
If its not the dome light, but the trunk light or some other item that should be off, it s probably the reason the battery got run down.
 
Here's the diagram of the '70 main circuits without markups.

1732906783746.png
 
Mattax said:
View attachment 1716333422

Cleaned this up a bit.
The fact there is a drop at the fuse box when everything should be off tells us something must be drawing power.
Pressure (voltage) only drops when current runs through resistance. No current flowing, then there is no resistance.
So something is on. It might only be the dome light. It could be a radio, but since the Alt is a the same voltage as the bat, I don't think its a bad diode in the alternator. Rather its something that is on a fused circuit.


I tried helping someo ne else on FABO with an e-body a few years ago and he too seemed to have an issue like this. The fusebox is different than a-body boxes and without being there I couldn't help him track it down.
If its not the dome light, but the trunk light or some other item that should be off, it s probably the reason the battery got run down.
Click to expand...
Dome light bulb is dead or bot working havent got to that yet, no trunk light, and the only think light wise that doesnt work is the instrument panel light dimmer switch which controls lights, i posted you my phone number as well
 
Removing the connector engine side. question on the main harness plug on firewall
I think the '73 e-body is similar connector but would need to see it to say for sure.

Discussions on cleaning here:
Cleaning bulkhead connectors
I like these but they only can get accessible surfaces.
Plus electric cleaner, I use both Deoxit 05 or stronger and CRC quick dry depending on the situation and what I have available.

The failure locations are often at the wire crimp and insulation support.
You'll need a flattened cotter pin or something like that to release the female terminals
 
Last edited:
J.B. said:
Dome light bulb is dead or bot working havent got to that yet, no trunk light, and the only think light wise that doesnt work is the instrument panel light dimmer switch which controls lights, i posted you my phone number as well
Click to expand...
The current leak is something that does work, a broken wire that is touching ground, or something like that.
For example if the wire going to the dome light is broken but rubbing on the body, that creates a short. A good short should blow fuse. So this is somehting more sublte. Try removing all fuses on the hot side and see if the votlage drop with everything off goes away. There's other ways to track but thats a simp[le way to eliminate possibilities. Problem could be in the box itself. its a bit different than most of the A-body boxes.
 
J.B. said:
Will do some more digging on Saturday with these extra suggestions thanks a bunch this is helping me narrow this down
Click to expand...
I lot of good ideas here. Some complicated and some not. I always like to try the "NOT" first. I always keep an electric meter in all my vehicles ($10-$20 cheapies). Any issues, the first thing I check is at the battery. If the vehicle is running you should have 14 or a little higher volts at the positive cable, if so, the same at the battery post. If different you may have a dirty connection there. If lower than 14 votes coming in to the battery, follow others ideas. Next test would be for the battery. Car off, check voltage at cables, than battery, should be same or again dirty cable. If same, check again in an hour or two and if you have a drop, under 12 or just a little over you may have a bad battery. A good battery should read around 12.75 votes.
 
Ok after extensive searching and literally unraveling the electrical tape from the entire charging system circuit i found the god damn culprit and some other unrelated deplorable attachments. Unreal someone would do this instead of purchasing a new connecting harness like why!? The alternator output or “black cable” was not a solid run but was married together with a butt connector about halfway im engine bay before the bulk head connector obviously it being covered with electrical tape hid the problem. After everything checked out over and over the only thing to do was start from one side and unravel all the tape and look for a problem amd boy was I surprised at the stupidity! Damn thing is burnt up and a few inches on either side of it has rippled singed outer wire coating, no damn wander i was barely charging. Glad i found this and didnt give up would of started a damn fire! Also found some deplorable connections twisted together wires in the reverse light harness for the starter terminal. Other cut up spliced areas and not sure if the red charge wire and yellow wire fittings are factory or a better repair. it is a different style connector not a standard open butt but rather a sealed style fitting. Those seem like good repairs but wither way im buy two brand new harnesses because these are a mess.

IMG_1809.jpeg


IMG_1811.jpeg


IMG_1810.jpeg


IMG_1814.jpeg
 
Here's my tips for the repair.

If available download a 1973 Dodge or Plymouth Service Manual. Most of the wiring diagrams will be in the Chassis manual. Some of the body harnesses and extras will be in the Body Manual.
www.mymopar.com -> service manuals

Your car probably came with standard harness but there were heavy duty and fleet optioned cars. I mention it for two reasons.
1. Some of us have borrowed the wiring concepts used on those options for our own cars. It is more work, but something to consider.
2. The reddish wire going into the multi-connector looks pretty fat. Its possibly a 10 gage wire, and its possible your car has some heavy duty wiring. However usually when heavy wiring was used instead of going into the multiconnector, they used a locked bullet connector and then a grommet through the firewall.

I don't know if '73 Shop Manuals will have any harness illustrations. A few years have them, or have them for options and accessories.
If you're really interested, Faxon has some factory assembly drawings which will show the harnesses and where to attach etc, but don't know if they have your car and year. If they don't, don't bother.

There is some good info here on FABO about making splices, and replacing terminals.
This method can work with or without soldering.
www.forabodiesonly.com

Inline wiring splice clips........from the Dodge RAM service manual

!!HUH!! Old man learned something. Was into the Dodge ram service manual and saw a little drawing about inline splice "clips" A simple little "U" shaped clip that you wrap around the "running" wire along with the "to be added" tap wire, and crimp. Solder........Makes a...
www.forabodiesonly.com www.forabodiesonly.com

www.forabodiesonly.com

Clever splice

Saw this a few months ago, just saw it again. Clever splice, looks very strong. WNEC™ - Waterproof Solder Wire Connectors
www.forabodiesonly.com www.forabodiesonly.com

In the engine bay I try to use wire and heat shrink with oil resistance and tolerant of higher heat.
I live close enough to a marine supply that sells wire by the foot as well as in small rolls, so thats a source for me.
In the passenger compartment, general purpose automotive wire will work fine.

Here's some threads about crimping wire terminals
A bit of Wiring 101

Checking crimps

Lets Talk Open Barrel Crimpers - Reviews and Discussion



When done, rewrap the wires in a nonsticky harness tape and secure in the original holders so nothing chafes.
 
Last edited:
J.B. said:
Other cut up spliced areas and not sure if the red charge wire and yellow wire fittings are factory or a better repair. it is a different style connector not a standard open butt but rather a sealed style fitting. Those seem like good repairs but wither way im buy two brand new harnesses because these are a mess.
Click to expand...
If it was me and my harness was untapped I would replace the wires end to end with new crimped on connectors. Use a REAL crimping tool American Autowire sells really good ones. Practice making crimps a few times on spare wire. Most of what I see has terminals on the ends that can be removed from the plastic connectors.


OR

as you noted buy a replacement OEM style engine harness
 
MAN! When you mentioned you had "new wiring" I thought you had a "new" harness
 
67Dart273 said:
MAN! When you mentioned you had "new wiring" I thought you had a "new" harness
Click to expand...
I had a new under dash wiring, but the engine side was older. I am just gonna go ahead and buy brand new engine side harnesses.
 
You must log in or register to reply here.
-

Back
Top