Help...charging problem
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
I will ask again:
Do you have power coming from the Ignition switch to the alternator?
Without this voltage from the Ignition switch it will not charge.
You should have battery voltage on this wire at the alternator.
It should be a light green wire with a red stripe.
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Do you have power coming from the Ignition switch to the alternator?
Without this voltage from the Ignition switch it will not charge.
You should have battery voltage on this wire at the alternator.
It should be a light green wire with a red stripe.
/
Thread Starter
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New User
Joined: May 2003
Posts: 20
Likes: 0
Ok. Did that. Used negative battery terminal and had it revved right up. Only 2.43 volts. Is the new alternator bad? Or voltage regulator?
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New User
Joined: May 2003
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Sorry took so long, I didn't realize there was a 2nd page. Yes power is coming thru the ignition switch. 12.66 volts. Same as battery.
Senior User
Joined: Oct 2011
Posts: 193
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The battery is the filter capacitor for the charging system and also supplies the voltage (current) to the fields of the alternator. If the battery cable is pulled off while charging the spike in the electrical system can go as high as 100 Volts. The regulator can not work without the battery either.
TG5611 - start as far upstream as possible & work down. So test voltage at the alt+ bolt & the alt case as negative. If low voltage it's the alt or regulator.
If good, then test at battery. If you're losing voltage between the two it's the wiring.
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New User
Joined: May 2003
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OK. So here's where I stand. Alt light still on. Battery not charging. Tested the Alternator directly from the back (the red terminal) with a ground going directly to the battery. Only getting about 2.5 volts with engine at high idle. Jumped the A and F (orange and yellow wires) at the voltage regulator so I should have gotten a full field charge, but nothing. Battery still at 12.66 volts and alternator still only putting out 2.5 volts. I'm starting to think this new remanufactured alternator is no good. I mean if I jumped the voltage regulator wires, It should have charged. Correct? Also I read that if the ALT light is on, it wont charge. This I don't understand. So how do I get the light off so it will charge? Confusing. Any other ideas before I pull this alternator out and go have it checked? Thank you everybody for your time and help. I'm going to bed now....stressed!!!
Senior User
Joined: Oct 2011
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Do this test with the ground at the alternator case so you can eliminate the chance that the ground from alt to battery is faulty. This is unlikely but worth checking. Most likely the alt is bad.
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
Also make sure the regulator is well grounded. It will not charge if it is not grounded. A lot of alternators have been changed out because the regulator had lost its ground. It grounds with its mounting screws. Also make sure whatever it is screwed too is grounded back to the battery.
The large ground cable from the NEG post should be running to the engine block. If this is not the case then move it. Then check that you have at least a 10GA wire from the NEG post of the battery to the Body (not the frame).
The large ground cable from the NEG post should be running to the engine block. If this is not the case then move it. Then check that you have at least a 10GA wire from the NEG post of the battery to the Body (not the frame).
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Logistics Pro
Joined: May 2004
Posts: 4,998
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From: Maryville
I can't tell you how neglected engine ground straps are, people act as if they don't have one, most electrical issues regarding charging are cause by them, get good heavy battery cables and bolt it to the block-frame-battery and watch in surprise how it changes things!
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New User
Joined: May 2003
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Well I'm just about ready to give up. Today I went through all the grounds and cleaned them up. The ground running from the block up to the voltage regulator looked bad, so I replaced it. Nothing changed. Something strange though...the battery measures 12.63 volts but when I turn the key all I get is the crazy clicking sound like its dead. So I through my jumper on it and it fires right up. Could this battery be bad even though it measures good and even the little eye on it is green? Also could the ALT lightbulb be bad but still light up without shutting off therefore preventing the alternator from charging? I know I'm grasping at straws here, but I'm sick of buying things I don't need. Thanks again everyone.
