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Alternator is not charging even with a new alternator

Tiny
KENNY F150
  • MEMBER
  • 1982 FORD F-150
  • 6 CYL
  • 2WD
  • MANUAL
  • 226,000 MILES
The alternator is not charging even with a new alternator. The old one was wired with the feed from the battery terminal going to the ignition module through the hot wire from the battery to the ignition module. The field wire terminal was wired to the a port on the regulator and had a second wire going nowhere but had a plug on it that appeared to go to the carburetor. The ground prong on the alternator was not grounded and the starter terminal was not connected. Needless to say I didn't make it far before my battery was dead.
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Thursday, March 21st, 2019 AT 5:16 PM

18 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good evening,

I attached a wiring diagram for you to view with the wiring required for the alternator to work.

Roy
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Thursday, March 21st, 2019 AT 5:32 PM
Tiny
KENNY F150
  • MEMBER
  • 3 POSTS
Thanks, but I also need the wiring diagram for the solenoid. I did not see it in the diagram. Two of the wires from the alternator with fusible links were also attached to the battery hot side of this unit and I presume the hot feed from the alternator should go straight to the battery.
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Thursday, March 21st, 2019 AT 5:39 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Try this.

Roy
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Thursday, March 21st, 2019 AT 5:44 PM
Tiny
KENNY F150
  • MEMBER
  • 3 POSTS
Thank you so much! That is what I have spent most of the day looking for and my battery is now charging back up from 5.5 volts to 11.8 volts. I'll check the alternator when it gets high enough to crank the truck to see if it is charging while running. I can't thank you enough. I am sure I will have more questions in the future.
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Thursday, March 21st, 2019 AT 5:49 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
You are welcome.

You need 12.6 for a full charge.

Always glad to help.

Roy
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Thursday, March 21st, 2019 AT 5:54 PM
Tiny
DAMEFIYAFIGHTER
  • MEMBER
  • 1 POST
  • 1979 FORD F-150
  • 6 CYL
  • 4WD
  • MANUAL
  • 122,765 MILES
I have 79 f-150 4x4 300 striat 6 I have put in new starter new selinoid new altenator and new regulator and the alt light on the dash is still on and it is not charging the wiring is all good all hooked up right I don't know what eles to do please help
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Friday, January 22nd, 2021 AT 11:45 AM (Merged)
Tiny
DAVE H
  • MECHANIC
  • 13,383 POSTS
Use a voltmeter. Put red probe to alternator large B+ terminal and voltmeter black probe to a ground (battery ground). With engine @ idle you should be getting between 13 and 14 volts on voltmeter. If you are not then new alternator is also bad. If you are getting good voltage from alternator you will have to recheck your wiring !
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Friday, January 22nd, 2021 AT 11:45 AM (Merged)
Tiny
TROESTLER
  • MEMBER
  • 1 POST
  • FORD F-150
Hi guys, props for this site. Amazing. Anyways I own a F-150 1987 4x4 302 5.0L, 4-speed standard, 275 000 kms with rebuilt engine and tranny. Recently my charging system has started acting up and won't hold any charge. I automaticaly assumed it was my alternator as my headlights were dimming up with the RPM speed before the problem occured. I put a brand new one in, changed my regulator and alt. Harness, changed my battery terminals, recharged my battery to about 12.4V, and the altenator still won't charge. It is pretty obvious then that it is a short, isn't it?
I took my truck to the mechanic this morning to get the battery tested, after a few tests, the guy told me it could be the alternator that could be faulthy otherwise it would probably cost me big time to locate that short in order to get it fixed.
Anyways, do you have any heads up to give me, can I locate the short myself or should I just leave it to them. If you do think it's possible, what tools do I need, etc.
Thank you so much, hopefully you can help me save some big bucks that I don't have!
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Friday, January 22nd, 2021 AT 11:46 AM (Merged)
Tiny
MIKEYBDMAN
  • MECHANIC
  • 623 POSTS
Not sure I am buying the short idea. Usually when things short, fuses blow, and if its between the battery and the altenator it should be easy to find.

Let me ask you this. Is your Charge Indicator in the instrument panel showing a no charge indication? I guess it is a light on if not charging, and off if charging.

I good test is to check your battery voltage while not connected. Connect the battery with all lights off and the ignition switch off. Does the battery voltage go down? If yes, find out what is drawing current. Maybe a glove box light, or something. Another way to find out what is drawing down is pull fuses to eliminate circuits. Make sure you have a detailed map of which fuses go where before pulling more than one.

Ok, if the voltage stays the same, start the vehicle and see what the voltage is on the battery with the altenator running. I know before you said you changed both the altenator and the regulator, but why did you change the alt harness? Was something bad, corroded, or burnt?

My fist thought is like the mechanics of the altenator or regulator. You might want to trace back the ground for the regulator and see if it is sound. The diagram shows a radio noise capacitor at the ground. Maybe that had gone bad. Just trying to through some ideas your way.
Good luck and let us know what fixes it.
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Friday, January 22nd, 2021 AT 11:46 AM (Merged)
Tiny
TAURUSWHEEL
  • MECHANIC
  • 718 POSTS
Battery takes no charge? Or does it die off after a few days? Will the truck run all day if you start it? If the charging system has issues, the battery can only run the vehicle until not enough voltage left to power. If the charging system is good, and the battery is shot, will continue to run until shut off, if not enough juice can be put in the battery, will not start without jump
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Friday, January 22nd, 2021 AT 11:46 AM (Merged)
Tiny
TIMTHETRUCKER
  • MEMBER
  • 1 POST
  • FORD F-150
Hi, I have a 1998 Taurus w/115000 miles. The battery light flickers on and off, when its on I dont have any charging, the light get dimmer, the blower fan slows down, but when the light turns off, seemingly at random, the lights brighten, and the fan speeds up. I checked the connections at the alternator and batery posts, nothing there is loose. Is there somewhere else I should be checking for loose wires, or might this be an internal problem at the alternator or some other part rewuiring replacement? Thanks, TimtheTrucker
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Friday, January 22nd, 2021 AT 11:46 AM (Merged)
Tiny
ACER
  • MEMBER
  • 2 POSTS
Sounds like the alternator or charging problem. Check that the battery is good and can hold a charge. If it is ok, then probally the alternator is going bad.
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Friday, January 22nd, 2021 AT 11:46 AM (Merged)
Tiny
KIMMIE6604
  • MEMBER
  • 3 POSTS
I replaced the battery and the alternator with no luck. Did you find anything else out about it?
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Friday, January 22nd, 2021 AT 11:46 AM (Merged)
Tiny
BRUCE HUNT
  • MECHANIC
  • 3,754 POSTS
I would say the original issue is an alternator problem and it sounds like a short in the alt.

The buick man did you buy the alt from parts store and have you had it checked to see if the alt is working. I don't care that you think it is new but I would wager it is rebuilt and they aren't always done right. Eliminate that, it is easy.
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Friday, January 22nd, 2021 AT 11:46 AM (Merged)
Tiny
BEARCATRIDER
  • MEMBER
  • 3 POSTS
  • FORD F-150
I recently lost my charging. I thought it to be the alternator and replaced it I also put in a new battery and clamps at the same time. This worked for about 10 minutes than the alternator quit charging. I took the rebuilt alternator back and they replaced it with a new one. This new one wouldn't work at all at first but cuts in intermittently. When it works it works it works fine (14-15 volts) even under load. After a short while it will cut out again. The power feed to the alternator remains constant and doesn't seem to be the problem. I'm thinking that the fault may be in the connector plug at the alternator. Any ideas?
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Friday, January 22nd, 2021 AT 11:46 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
The IVR internal voltage regulator controls the output of the alternator-

Full field the alternator by jumping the connector A to F and see what happens.

When key is in ON position the I pin on the connector should have battery voltage.-If not check the ignition switch.
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Friday, January 22nd, 2021 AT 11:46 AM (Merged)
Tiny
BEARCATRIDER
  • MEMBER
  • 3 POSTS
If I jump A-F I get charging.
I have battery voltage at the connector.
It's almost like the regulator cuts out and then doesn't reset itself. Sometimes it will cutout and restart on it's own while the engine is running. Also sometimes I can get it to reset by disconnecting the battery and then restarting. Is it possible that I may have a short in the wire running to the voltage gauge. This is the only wire that I haven't really followed back all the way. I would blame the regulator but this is the third alternator that I'm on now and if the regulator is at fault, something has to be causing it to fail.
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Friday, January 22nd, 2021 AT 11:46 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
If I jump A-F I get charging.
I have battery voltage at the connector.
It's almost like the regulator cuts out and then doesn't reset itself. Sometimes it will cutout and restart on it's own while the engine is running. Also sometimes I can get it to reset by disconnecting the battery and then restarting. Is it possible that I may have a short in the wire running to the voltage gauge. This is the only wire that I haven't really followed back all the way. I would blame the regulator but this is the third alternator that I'm on now and if the regulator is at fault, something has to be causing it to fail.[/Quote:b094a6fd3f]

Could be that wire-causing the regulator to go out. And again some systems the computer controls the regulator. Check that out too.
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Friday, January 22nd, 2021 AT 11:46 AM (Merged)

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