Battery voltage at 11 constantly even after new battery/alternator

captndave737

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Feb 14, 2006
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I had a test light hooked to the red wire on the alternator side and got nothing. But when I connected it to the red wire on the battery side it had power.
Since the wire runs directly from the alternator to the battery that's Impossible unless the wire is broken. take the red wire off the battery and the alternator and do a continuity check. The wire runs along the bottom front of the engine in the funky conduit that's attached to the bottom studs on the front cover.
 

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GNbythebay

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Since the wire runs directly from the alternator to the battery that's Impossible unless the wire is broken. take the red wire off the battery and the alternator and do a continuity check. The wire runs along the bottom front of the engine in the funky conduit that's attached to the bottom studs on the front cover.
Ok I will try that. I never did a continuity check but I’ll figure it out and let you know what I find.
 

captndave737

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Feb 14, 2006
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Do you have a multimeter? You need one. Put it on Ohms, put one lead on the wire at the battery end and one end on the wire at the alternator end. MAKE SURE THE WIRES ARE DISCONNECTED. The meter should read infinity before touching the wire and zero while touching the wire.
 

ScottHeidinger

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May 2, 2015
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I had a test light hooked to the red wire on the alternator side and got nothing. But when I connected it to the red wire on the battery side it had power.
Reading this I assumed you had pulled the wire off the battery? You will not have power at the alternator with the battery disconnected


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earlbrown

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May 26, 2001
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I had a test light hooked to the red wire on the alternator side and got nothing. But when I connected it to the red wire on the battery side it had power.
You need to be using a meter, not a light. BUT...

If the alt stud won't light up a light, but the battery is hot, you have a bad battery cable. That red wire you see on the back of the alternator is the same red wire you see hooked to the positive terminal at the battery.


Here's your next test. (it's a two parter)

First, put your test light on the ALT post and then wiggle the crap out of that wire at the battery. If the light blinks on and off, you've found the problem.

Next, jab the light probe into the red wire about an inch from the battery. If it's dead, you found the problem.
 

GNbythebay

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So I went out and bought a multi meter.
You need to be using a meter, not a light. BUT...

If the alt stud won't light up a light, but the battery is hot, you have a bad battery cable. That red wire you see on the back of the alternator is the same red wire you see hooked to the positive terminal at the battery.


Here's your next test. (it's a two parter)

First, put your test light on the ALT post and then wiggle the crap out of that wire at the battery. If the light blinks on and off, you've found the problem.

Next, jab the light probe into the red wire about an inch from the battery. If it's dead, you found the problem.
Hooked one end up to the positive battery cable and the other to the alternator cable it read 1 when I had one of the probes on just one side but when I connected both probes one to the batter cable and one the to alt cable it read around 500-600. Does that mean my battery cable is good? With just the test light I tried wiggleing the battery cable while I had the test light on the alt and still got no light.
 

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GNbythebay

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Do you have a multimeter? You need one. Put it on Ohms, put one lead on the wire at the battery end and one end on the wire at the alternator end. MAKE SURE THE WIRES ARE DISCONNECTED. The meter should read infinity before touching the wire and zero while touching the wire.
Just bought a meter and this is what I got. The one is before I touched the wire and got an -500- -600 number. Like I said this is my first time using a meter so I could of had it on the wrong setting but does that mean my battery wire is good?
 

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earlbrown

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You've got the meter set to ohms. That's (sorta) the right test if you have the battery cable loose from the car.

Here's how you get learn to be friends with your DVM. Sent the voltage to 20 on the VDC scale and touch both leads to the battery. That will give you the battery voltage while unloaded.

Then move the positive cable over to the ALT post. It should read almost the same as the battery.
 

captndave737

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Feb 14, 2006
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Just bought a meter and this is what I got. The one is before I touched the wire and got an -500- -600 number. Like I said this is my first time using a meter so I could of had it on the wrong setting but does that mean my battery wire is good?
1.To check continuity set the meter to 200 ohms not 200k ohms.
2.Touch the leads together. The meter should read near zero. There might be an adjustment to zero it out while touching the leads together. If not anything near zero is ok. When the leads are apart it should read infinity.
3. Disconnect the red lead from the battery AND the alternator.
4. While BOTH are disconnected touch one lead to the red wire near the battery and one to the red wire by the alternator. Doesn’t matter which lead goes to which end. It should read at or near zero. If not the wire is broken or severely corroded.

Remember, it’s just a piece of heavy gauge wire that runs directly from the battery to the alternator.

Like Earl said, with the terminal disconnected you can now set the meter on DC volts. Set it on the 20v scale. And measure the voltage on the battery by touching the red terminal to the +battery post and the black to the - battery post.
 

GNbythebay

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You've got the meter set to ohms. That's (sorta) the right test if you have the battery cable loose from the car.

Here's how you get learn to be friends with your DVM. Sent the voltage to 20 on the VDC scale and touch both leads to the battery. That will give you the battery voltage while unloaded.

Then move the positive cable over to the ALT post. It should read almost the same as the battery.
Just did this and the battery was reading 12 v than when I moved the prong from the positive battery cable to the positive alternator cable it read 0 v. This has to mean the wire itself is bad?
 

earlbrown

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May 26, 2001
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Just did this and the battery was reading 12 v than when I moved the prong from the positive battery cable to the positive alternator cable it read 0 v. This has to mean the wire itself is bad?
Yep.

Jab the positive probe into the charge lead about an inch from the battery terminal. Odds are it'll read 0VDC too. A quick fix would be to install a cheap clamp on terminal, or put a ring terminal on the charge lead and hook it too the positive post.


What's bad is I identified over 1/2 volt drop between my battery and ALT several years ago. I bought everything I need to build updated cables with a larger gauge charge lead, new orange ECM wire, 16 ton crimp tool, ends etc...

.....and still haven't built an upgraded cable yet. lol
 

GNbythebay

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Yep.

Jab the positive probe into the charge lead about an inch from the battery terminal. Odds are it'll read 0VDC too. A quick fix would be to install a cheap clamp on terminal, or put a ring terminal on the charge lead and hook it too the positive post.


What's bad is I identified over 1/2 volt drop between my battery and ALT several years ago. I bought everything I need to build updated cables with a larger gauge charge lead, new orange ECM wire, 16 ton crimp tool, ends etc...

.....and still haven't built an upgraded cable yet. lol
Do you think they sell a battery cable for our cars in the local auto parts store or do I have to shell out 100 bucks and buy the one Casper electronics offers.
 

ScottHeidinger

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May 2, 2015
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I just ran a 4 gauge wire from the alternator to the battery connection. The wire came from Walmart $12. I had to modify the connector to get it hooked up. I have 200 amp alternator so that little stock wire wasn’t big enough. You can probably find a 6 or 8 gauge wire there is you want a cheaper fix.


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GNbythebay

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I just ran a 4 gauge wire from the alternator to the battery connection. The wire came from Walmart $12. I had to modify the connector to get it hooked up. I have 200 amp alternator so that little stock wire wasn’t big enough. You can probably find a 6 or 8 gauge wire there is you want a cheaper fix.


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I feel stupid to say this but the whole time I was testing on my Hotwire kit fuel pump wire instead of the wire that runs back to the alternator. After realizing that I did test on the alternator wire and it had power going through it. So now I feel like I am back to square one! Also just installed the field fix Casper kit and it did not help at all.
 

ScottHeidinger

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May 2, 2015
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Are you sure you connected the Casper’s field fix correctly?
I would still like to know what the voltage is on the brown wire on the alternator.
Have you inspected the alternator pigtail for the brown wire for any physical damage that could cause a bad connection?
The stock charging system is very basic and not very good in my opinion but it should be adequate for a stock car. It’s basic because the voltage positive wire is on one side of a dash bulb and the other side (ground) goes to the alternator via the brown wire. As basic as I can explain this brown wire needs to have a reduced voltage (NOT 12 volts) to tell the alternator to work. If the bulb is blown then u will have no voltage and the alternator will not charge. If the alternator is bad this circuit shorts out and the dash light will come on if the bulb is good.
If you don’t log and look at voltage or don’t have a volt gauge you may be surprised when you see the bouncing and often low voltage the stock setup provides. I was commonly seeing 11.8 to 13.8 but it was changing constantly. After a lot of reading on this forum I found many members had good results with a newer alternator pigtail that has the sense wire in addition to the wire for the dash light. I connected the sense wire to the power master connector and the dash light wire to this pigtail and now my voltage is a lot more steady at 13.5 to 14 volts. The difference this makes in everything from the AC blower to my radiator fans is amazing.

Please verify your voltage on the brown alternator pigtail for us. With the Casper’s field fix and/or without it.


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bpman1234

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Jan 24, 2011
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So i just went through this yes check that volt bulb i clean the contact on bulb and tape .but also the plug that the cluster snaps into on the back sometimes after al this time will not have good contact.forgot what color the alternator was but i tried to bend it slso yo make it have more tention i clean then all and spread them yo have more tention.it was happening no and then intermittent.it eould charge good then all of a sudden it would go down to 9. 10. Volts then one day it happen and i push the cluster in just to see if it would help and it went right up to 12 volts thats how i figured out it was that plug connection .but after all that the scanmaster still only read 12 volts orso then i changed that really old fuze and it read 13.8. Orso. After one of our members mentioned it. Hope this helps .
 

captndave737

Well-Known Member
Feb 14, 2006
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Raleigh, NC
If you have the field fix and it’s still not charging I would check the voltage at the wastegate solenoid pink/ black wire. It should have 12v with the key on.
 

GNbythebay

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Jul 28, 2016
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Are you sure you connected the Casper’s field fix correctly?
I would still like to know what the voltage is on the brown wire on the alternator.
Have you inspected the alternator pigtail for the brown wire for any physical damage that could cause a bad connection?
The stock charging system is very basic and not very good in my opinion but it should be adequate for a stock car. It’s basic because the voltage positive wire is on one side of a dash bulb and the other side (ground) goes to the alternator via the brown wire. As basic as I can explain this brown wire needs to have a reduced voltage (NOT 12 volts) to tell the alternator to work. If the bulb is blown then u will have no voltage and the alternator will not charge. If the alternator is bad this circuit shorts out and the dash light will come on if the bulb is good.
If you don’t log and look at voltage or don’t have a volt gauge you may be surprised when you see the bouncing and often low voltage the stock setup provides. I was commonly seeing 11.8 to 13.8 but it was changing constantly. After a lot of reading on this forum I found many members had good results with a newer alternator pigtail that has the sense wire in addition to the wire for the dash light. I connected the sense wire to the power master connector and the dash light wire to this pigtail and now my voltage is a lot more steady at 13.5 to 14 volts. The difference this makes in everything from the AC blower to my radiator fans is amazing.

Please verify your voltage on the brown alternator pigtail for us. With the Casper’s field fix and/or without it.


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Quick update with my voltage problem. After installing the field fix it seemed to help but not 100% the car now sits around 11.5-12 volts. I took it to the auto parts store to test both battery and alternator (which are new) and the alternator came out as being bad. I bought any tuff stuff performance 140 amp alternator off of summit and I am going to try that one out. Also the bracket that connects to the exhaust manifold and alternator I do not have bolted down. Could that be why the alternator is not working at 100% btw the bracket is not connected because the aftermarket alternator I bought does not line up very well.
 

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