70 charger alternator not charging HELP! (60 amp)

[mudda_hunchie]

     A little background first.  About 4 years ago, took car to get it painted.  All wiring was in working order.  While they had it, the after market amp gauge ground out.  I finally found the ground to be in the bulk head connector on the wire going from the alternator to the amp gauge (black wire).  I cut old wires and ran a new replacement wireand new amp gauge.  Problem solved.
     Now, 4 years later, I first noticed car almost missing from time to time.  Not all the time.  This went on for a couple of months.  When I park the car for more than a day, I use a battery dissconnect switch.  A few days ago, I took about a ten mile trip and when I returned, car wouldn't start.  I charged the battery and the car started right up.  While the car was running, I turned battery dissconnect off and car went dead.  So I take the alternator to parts house for testing.  Alternator checks out good.  I checked ballast, has power on both sides with key on.  I checked voltage regulator by replacing, still no change.  When I remove ground cable from the battery, and use my test light, it shows a ground.  I leave alternator unhooked, unhooked the starter,  and it still shows ground.  I removed all the fuses and it still shows a ground at the neg battery post. 
     I tried bypassing the other wire (old wire) on the amp gauge and it still shows a ground.  I've gotten frustrated and don't know what else to do.  If I have to go under the dash chasing wires, that'll be  it for summer cruising, pressed and limited for time.  I don't think the green wire going to the alternator was showing any power.  Sorry for the lengthy post.  Any ideas would be appreciated.  If I left anything out, please ask.I guess it really is true, EVERYBODY LOVES 40 YEAR OLD WIRING!

[nascarxx29]

Being you have a 70 charger you should have a blue and green wire going to both alternator fields.Have you checked these wires for continunity.And for Key on power with a testlight.And be sure alternator and voltage regulator are well grounded.I check all my grounds with a 12 volt testlight.with testlight clip on connection on + positive side off battery.And when you touch alternator mounting point and voltage regulator mounting point.The test light lights up and you well grounded

[Nacho-RT74]

you must have 12 volts between green and blue wires arriving to alternator fields when switching key in run. Check if you have that

a "ground" test between batt negative and chasis will allways show continuity, because BULB FILAMENTS will make the continuity

[nascarxx29]

The ground check light test has worked for me . Customer had alternator rebuilt replaced voltage regulator and new engine harness and had charging issues. I Found by testlight alternator mounting point checking ground with the light .Someone powder coated the mounting bolt and spacer.Alternator had insufficient ground.Wire wheeled the bolt and spacer ends and it was good to go

[mudda_hunchie]

     Alternator has a good ground.  Green wire is not showing power with key on.  However, ground is showing at neg battery post and ground cable.

[Nacho-RT74]

green wire is REGULATED GROUND ( negative ) coming from regulator. Blue is constant positive from key.
need to put the key in RUN to check 12 volts between green and blue wires to get juice on blue and also activate regulator to get negative from green.

Regulator requires a good chasis ground. It takes the negative from there to send to alt field once procesed and regulated

[mudda_hunchie]

     I'll check it let yiou know the outcome.  Can't believe it's the ground though.  Car has been running fine and all of the sudden this started.  None of the grounds had been tampered with.  Thanks for the ideas.

[mudda_hunchie]

     I checked between blue and green wire with a test light with the  key on.  No light.  Blue wire shows power when test light grounded to the chasis.  Is regulator bad?   When I unplug regulator, I'm still showing a ground at the battery between neg post on battery and neg ground cable with test light between them.  I didn't have this problem before alt not charging.

[nascarxx29]

Hows the connections at the firewall where harness plugs in.Are you getting 12 volt battery voltage at the alternator connection point.And key on power at the voltage regulator connector unplugged from regulator at the blue wire.This same blue wire is the single wire at the ballast.Do you have key on power there
70 Charger underhood wiring diagram
http://www.mymopar.com/downloads/1970/70ChargerA.JPG

[HANDM]

Had the same problem with the 69, turns out it was the voltage regulator, I know 69 & 70 are different but it's worth a shot 

[Nacho-RT74]

ok, ground one of the fields on back of alt with a wire and plug the other field with the blue wire

YOU MUST GET JUICE coming from alt on that moment. DON'T REV UP THE ENGINE... just iddling because you are full fielding the alternator.

if you get juice from alt, then regulator damaged, green wire damaged or bag ground on regulator.

remove the ground wire added on alt field, plug the green wire as usual, unplug regulator and ground the green wire at regulator plug ( blue wire doesn't need anything just ground safelly teh green wire at regulator plug ). You will be testing the green wire conditions on that moment. If you get once again juice, green wire is in good condition, then regulator is bad or chassis ground at regulator could be wrong

[mudda_hunchie]

     Thanks for the help guys.  It's gotten late, but I'll do your tests on regulator first thing tomorrow.  What still worries me is the ground at neg bat post.  I have checked plugs at firewall. All wires on headlight wiring plug are showing backfeed(ground).  I'm thinking this ground may be what caused regulator to go bad, if that is what has happened.

[nascarxx29]

 

Just checking You do have the correct 70 type flat regulator.
Not the black box regulator used 69 and down.
The 70 Type dual field alternator can be used in 69 and down by grounding one of the alt fields. 69 and earlier year alternator will not work on 70 & up

[mudda_hunchie]

     cHECKED for continuity on the green wire.  It was good.  replaced voltage regulator with old spare.  Alternator now charging.   I'll go to town and swap out old regulator for new one.  Bought it at o'reilly and it had a lifetime warranty.  I still think ground at neg bat post could be causing me more trouble.  I'll install new regulator and let you all know what happens.


     I have replaced voltage regulator with new one.  Alternator is now charging.  Do you guys think that this ground that still exists could cause voltage regulator to go bad?  Any ideas?