# Alternator not charging and I have run out of ideas.



## Freddy_Krugerrand (Aug 19, 2012)

Car was charging fine for the last year. 66 GTO. Took alternator in and it checked out fine. Replaced the external regulator (old one was newish) and still no charge.
I checked continuity from the external regulator to the ends of each of the four wires off the external regulator and all had a nice loud beep. Car starts up instantly and runs great.

Battery light on dash works. 

Is there anything under the dash that could come loose to make it not charge? Any ideas on what to check next. Car was charging fine and now nothing.

I am out of ideas.


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## cij911 (Oct 25, 2017)

You need to check voltage output of the alternator (at the post of the alternator), as well as output of the regulator. Assuming the regulator is working correctly, then make sure the charging wire is intact (not open).

Do you have the factory wires on the starter? If so, and my memory is correct, the charging goes to the regulator down to the starter, connects to the starter wire and back to the battery.


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## Freddy_Krugerrand (Aug 19, 2012)

The voltage at the alternator is the same as the battery. There is no charging going on at all. Also no output at the regulator.

Perhaps my regulator is not getting voltage. Does it get voltage off the brown wire inside the car?


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## RMTZ67 (Mar 12, 2011)

Freddy_Krugerrand said:


> Car was charging fine for the last year. 66 GTO. Took alternator in and it checked out fine. Replaced the external regulator (old one was newish) and still no charge.
> I checked continuity from the external regulator to the ends of each of the four wires off the external regulator and all had a nice loud beep. Car starts up instantly and runs great.
> 
> Battery light on dash works.
> ...


 You say it starts up instantly but does not charge? Do you have to boost it? Just because the parts store test it and shows good does not mean it is always good. Had that happen on my f250. But since it was lifetime guarantee I asked for a new one. Fixed. Also had a bad ignition switch on my 67 that would not return itself all the way after starting it and the battery light would stay on even tho it was charging. If I am not mistaken if it kills you battery while driving its the alternator . If it kills the battery sitting its the regulator. Try taking a battery cable off while running, if it dies its a bad alternator. True story: back in the days they stole my friends battery at a partyarty: in the mountains. So we used mine to start it then put it back. He then drove home w/o a battery. So basically the battery is only to start it and run your accessories. Anybody feel free to correct me. It's been a long time since the 70's lol.


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## Freddy_Krugerrand (Aug 19, 2012)

If I wanted to switch to a single wire alternator charging system can someone recommend a alternator from autozone or oreilly that would work well?


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## cij911 (Oct 25, 2017)

Freddy_Krugerrand said:


> The voltage at the alternator is the same as the battery. There is no charging going on at all. Also no output at the regulator.
> 
> Perhaps my regulator is not getting voltage. Does it get voltage off the brown wire inside the car?


I am trying to triple check components and wiring.

1. Verify the alternator is working by testing the voltage output at the alternator.

2. Trace the wire from the alternator to the voltage regulator and verify the same voltage is being seen coming into the regulator (the wire may be broken or a connection that appears good is in fact not).

3. Confirm regulator output voltage (if nothing, it sounds like your regulator is the issue)

4. Check the regulator output / charge wire path and confirm connectivity to the battery (thru the starter).


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## falcon7x-014 (Sep 13, 2018)

If you dont think your getting voltage to the voltage regulator check input voltage with the ignition switch on. If not check fuse or ignition switch.


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