Same Problem again

[Sixt8Chrgr]

My ammeter reads 0 to negative charge depending what accessory is on. I have 12 volts at the back of the alt. I have a new alternator and voltage regulator. The last time this happened I took the car back to the mechanic that put the parts on. He fixed the problem without changing any parts. After the repair he told me that there was a bad ground to the voltage regulator. This all happened about 6-8 weeks ago. I called him today to ask him what he did last time and he could not remember. The wiring harness is a nightmare, broken insulation on about each wire. I am going to put a new harness on the car, but in the mean time does anyone have an idea of what the fix could be? Should I be focusing on the dark green wire that goes from the alternator to the voltage regulator. Or the ground wire from the alt to the wiring harness that then ties into the ammeter? I have a wiring diagram and a shop manual to refer to.

Thanks

[Nacho-RT74]

single or double field alt ?

electronic or mechanical regulator ?

-If single field alt with mechanical regulator, put ignition key in RUN position and:

Check for power ( 12 volts ) on IGN terminal of regulator. If not, blue wire section between internal splice what feeds reg on harness damaged, engine harness bulhead conector loosen, blue wire terminal on same plug rusty or loosen or ignition switch damaged. However you car start on so check for safety on bulkhead but is working at least up to ballast.

Then check 12 volts on field terminal of regulator ( where green wire is plugged ) . If not power, could it be damaged or bad grounded regulator.

Then check for power on brush plug green wire... If not, power there could be bad green wire.

-If double field alt with electronic regulator:

Same test at blue engine harness wire. Power on brush terminal and regulator plug. If not, same fail as above explained.

Negative coming from green wire at alt brush. If not, damaged or bad grounded regulator or broken green wire.

There is not GROUND WIRE arriving to ammeter, both are positive, one coming from alt stud ( black ) and the other one coming from batt ( red ), throught fuse link ( blue ) at starter relay stud. Becarefull BOTH WIRES ARE ALLWAYS HOT, for a while batt is connected

[Nacho-RT74]

Note, on singe field mechanical reg, green drives positive

on elect and double field, green drives negative

colors and splicing points are for real on diagram. I edited to show that.. some blurry because enlarged the file

[Sixt8Chrgr]

Thanks Nacho!

I have a single field alt with a mechanical regulator.

A few questions:

How is the voltage regulator grounded? Just bolted on the firewall?
I have a wire that appears that it is jumped on the alt. It has a spade connector on one end and a eye on the other. I have not checked the voltage at this location yet. Any idea what this is? It is in addition to the field and batt connections and does not appear to go anywhere?
On the battery lead coming out of the alt. I also have a purple wire that goes to the horns. Is this just the power for the horns?
Where would you buy a replacement wiring harness for a 68 Charger?

Thanks,

Lawrence

[Nacho-RT74]

How is the voltage regulator grounded? Just bolted on the firewall?

Yes

I have a wire that appears that it is jumped on the alt. It has a spade connector on one end and a eye on the other. I have not checked the voltage at this location yet. Any idea what this is? It is in addition to the field and batt connections and does not appear to go anywhere?

If you have that I would say you have DOUBLE field alt with a grouded brush to make it works like a single field. Single field alts have same two busjhes, just onme of them without prong and isolator and directly attached to chassis, If you have that jumper loosen around THAT'S the problem. You need one brush grounded to work with mechanical regulator simulating single field alt.

On the battery lead coming out of the alt. I also have a purple wire that goes to the horns. Is this just the power for the horns?
Where would you buy a replacement wiring harness for a 68 Charger?

dunno how is exactly the wiirng on 2nd gens on that equippment stuff, just the generic and big stuff available on ALL mopars. I just know how is wired all the equipment since 70-71 and up

[charger_mike75]

I had the same problem with the wifes dart, I cured the problem with all new wiring

[Sixt8Chrgr]

I had the same problem with the wifes dart, I cured the problem with all new wiring

What wiring did you replace? I plan on replacing the engine compartment harness except for the headlight harness. I will do that later.

[Sixt8Chrgr]

single or double field alt ?

electronic or mechanical regulator ?

-If single field alt with mechanical regulator, put ignition key in RUN position and:

Check for power ( 12 volts ) on IGN terminal of regulator. If not, blue wire section between internal splice what feeds reg on harness damaged, engine harness bulhead conector loosen, blue wire terminal on same plug rusty or loosen or ignition switch damaged. However you car start on so check for safety on bulkhead but is working at least up to ballast.

Then check 12 volts on field terminal of regulator ( where green wire is plugged ) . If not power, could it be damaged or bad grounded regulator.

Then check for power on brush plug green wire... If not, power there could be bad green wire.

-If double field alt with electronic regulator:

Same test at blue engine harness wire. Power on brush terminal and regulator plug. If not, same fail as above explained.

Negative coming from green wire at alt brush. If not, damaged or bad grounded regulator or broken green wire.

There is not GROUND WIRE arriving to ammeter, both are positive, one coming from alt stud ( black ) and the other one coming from batt ( red ), throught fuse link ( blue ) at starter relay stud. Becarefull BOTH WIRES ARE ALLWAYS HOT, for a while batt is connected

Nacho,

With the ignition switch on, I tested the various areas as you mentioned and this is what I have. 12 volts on the ignition side of the voltage regulator, 2.4 volts on the green wire side of the voltage regulator, 2.4 volts on the spade end of the green wire going to the alternator. 12 volts on the ignition side of the ballast resistor, 6 volts on the other side of the ballast resistor. I tried to better ground the VR but did not have any luck. I was going to clip an alligator clip to the base of the VR to ground to see if that would give me 12 volts on the green wire side of the VR but ran out of time. Do you have any other ideas? My gut tells me that I have a bad ground on the VR. Oh yea, I put another VR on the car before I started, and the VR I put on the car was like new and worked fine before I took it off. I do have another VR that I could put on if you think that would work.

Thanks for you help.

Lawrence

[charger_mike75]

I had the same problem with the wifes dart, I cured the problem with all new wiring

What wiring did you replace? I plan on replacing the engine compartment harness except for the headlight harness. I will do that later.

I replaced all the wiring from the dash forward.   

[Sixt8Chrgr]

I had the same problem with the wifes dart, I cured the problem with all new wiring

What wiring did you replace? I plan on replacing the engine compartment harness except for the headlight harness. I will do that later.

I replaced all the wiring from the dash forward.   

I replaced my wiring harness last night including the A/C harness. Still the same problem. I think I may have a bad VR. Who knows?

[charger_mike75]

did you replace the dash harness and fuse block as well?