An Electrical Nightmare

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tsa_035

tsa_035

72 Plymouth Duster
Joined
Feb 11, 2010
Messages
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Location
Santa Clarita, CA
Hey everyone... I have an electrical issue (what else is new right?!). Besides the point to getting a new battery now, I charged up the battery and cranked the car over. When it starts the amp meter fluctuates between -10 and -15. When I open a door it will drop to -20. With the car idling I can not even hear the horn... All light are extremely dim. Now lets have some fun (car running, door open, and put on a turn signal) -30.

Underneath the dash, is a nightmare of disconnected wires, broken wires, and some wazzoo splicing job some dumb kid (me) did! Well at least I soldered it!!!

On top of it, About 15 years ago I think I screwed up the electronic ignition wiring... For some reason I have three ballast resistors (1 for windshield wiper, 1 for the MP electronic ignition I put in, and 1 to the voltage regulator).

Any input on where to even begin would be greatly appreciated!
 
Get a new underdash harness for a starting point then try to reconfigure the rest to the factory schematic. I know PIA but just my opinion.
 
halifaxhops said:
Get a new underdash harness for a starting point then try to reconfigure the rest to the factory schematic. I know PIA but just my opinion.
Click to expand...

That is what I was kind of thinking, or going to a painless (painful) wiring harness...

Just to add more of the mess... It ran great for many years... Only in the last year I developed this draw in the system that is killing me!!!
 
Aussiemopars said:
A resistor in the voltage regulator circuit doesn't sound right either...
Click to expand...

Yeah I was looking it up tonight and was like wait a minute... Printed out the schematics and thinking this makes 0 sense.... I should be able to run it all via the MP electronic ignition right???
 
That would be sending the wrong feedback voltage back to the alternator to give it enough charge. Is the battery constantly going flat?
 
I recently used a Ron Francis kit for a B body. It comes with most of the stuff you would use for an A body including a new light switch and floor dimmer switch.
 
Three ballast resisters?
The purpose of a ballast resister is to reduce the voltage (usually ignition), so if you somehow rout the feed through one ballast resister and into another......

I no expert but if the issue is a "low voltage" condition....and there's 3 voltage reducers in the mix.....I think that might be the place to start.

Best of luck on it. let us know how you make out
 
tsa_035 said:
Underneath the dash, is a nightmare of disconnected wires, broken wires, and some wazzoo splicing job some dumb kid (me) did! Well at least I soldered it!!!
Click to expand...
Like halifaxhops wrote, a factory replica harness would be a good way to go.

That said...
tsa_035 said:
On top of it, About 15 years ago I think I screwed up the electronic ignition wiring... For some reason I have three ballast resistors (1 for windshield wiper, 1 for the MP electronic ignition I put in, and 1 to the voltage regulator).
Click to expand...
If you installed the electronic ignition, then just one ballast resistor - same as the points ignition. Don't worry about the resistor for the wiper right now. If there's one on the VR, that will be an issue.

... and if you want, its not mission impossible to figure it out. Three things to get started.
1. Do this:
scott657 said:
MyMopar - Mopar Forums & Information - Service Manuals
Download the Manual for your vehicle. Print out the diagrams and start going wire for wire
Click to expand...
Some masking tape labels for the wires, and colored pencils for the diragram may help.
Skim through this thread for some advice on rewiring. Use Open Barrel terminals & crimpers, Packard 56 and Chrysler style for most. WIRING NIGHTMARE
2.
tsa_035 said:
When it starts the amp meter fluctuates between -10 and -15. When I open a door it will drop to -20. With the car idling I can not even hear the horn... All light are extremely dim. Now lets have some fun (car running, door open, and put on a turn signal) -30.
Click to expand...
Try to stop doing that. Pushing 30 amps through the charging circuit any length of time is not the best thing.

3. Begin by tracing the charge and run circuits. The ignition and charging circuit should not be pulling 15 amps if the battery was fully charged before starting.
You can use this simplified diagram of those two circuits and convert colors etc to match your specific car.

Main_charging_wires_plus.png
 
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On a '72, the blue RUN wires go to ballast resistor, the regulator, and the alternator field. The connection at the regulator is so to tell it system voltage. its just a just a measuring point. Power to the alternator field from the blue wire flows through the windings - and out the green wire to the regulator. The regulator controls the connection to ground. (If the green wire is grounded max current flows).
With an electronic box, a second connection is made on the coil side of the ballast resistor.
Alternator's black wire is power output. It is always hot. It will be at battery voltage when the alternator is not producing power.
Some illustrations of power flow in Understanding Charging Systems with Ammeter
 
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tsa_035 said:
Any input on where to even begin would be greatly appreciated!
Click to expand...

1...FIRST thing as suggested above is go to MyMopar and download the closest you can get to the correct factory service manual, and while you are there hit the "wiring" button and download the aftermark (2 pages) wiring diagrams, which are NOT factory, but are sometimes easier to follow

2...Determine why it is not charging. Find the "high voltage" connection on your ballast resistor. This should be the one jumpered to another end terminal. Read that voltage 'running' and find out what that voltage actually is

Below 13V not charging.......not good
About 14V running.......about normal charging
Above 15.5.........over charging, not good

Now determine why the alternator is not charging

Disconnect the GREEN field wire, and hook an alligator clip lead from that alternator terminal to ground with the key "in run." You should see a small spark every time you do that. With the clip lead in place and the key in "run" measure the blue wire at the alternator field. Do not disconnect it, probe with the connector in place. This should be VERY close to 'same as battery.'

Now start the car, with your meter hooked to battery, Slowly bring up RPM. Voltage should start to rise, adjust engine RPM to keep it below 16 or so.

If it does NOT and is below 13V the thing is not charging.

Post back with results
 
Since you have to start over again somewhat, I would start with simplifying the wiring and do some mods you want to have done anyway in time;

- Install a HEI module instead of the Mopar ECU. This deletes the ballast resistor right away and everything runs on full 12-14v battery voltage.
Best to switch all this with a relay too.

- Next install a relay in the headlight wiring to take the electrical load of the headlight-switch.
Another possible fire-source eliminated.

- 3rd; bypass the AM-meter completely and run a new thick gauge wire through a dedicated firewall connector. Install a Volt-meter.
This relieves the bulkhead connector of another high current wire.
 
Hey everyone, and thank you for all of the input. Here is what Iv'e done so far.

1 - went through and rewired the entire ignition system. What I found was some very poor connections (not mine) that were stripped and wrapped around each other and taped up.

2 - I went under the dash and started at the fuse box and found numerous wires had become dislodged and disconnected. (I have lights again!)

3 - Only three wires left underneath the dash to trace and figure out where they go to. 2 red wires (maybe 18 gauge) coming from the steering column and a black wire maybe 16 gauge coming from steering column.

So far when I started the car it is showing a very light discharge on the system. Horn is still extremely low and will be checking the relay tomorrow.

Double checking the battery after it charges to see if it will hold a charge. Last I checked it was holding at 12.8. Could not check volts with the car running re: ran out of gas :(
 
Aussiemopars said:
That would be sending the wrong feedback voltage back to the alternator to give it enough charge. Is the battery constantly going flat?
Click to expand...
The blue wire to the voltage regulator is fed off the resistor, but it is on the high voltage side. IF the voltage to the regulator is low, it OVERCHARGES the battery.
 
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