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New alternator will not charge battery

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Old 04-18-2010, 01:07 PM   #1
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New alternator will not charge battery

I am almost finished with this project but need some help!

May 4runner has a 22re in it first of all.

I originally noticed that my 4runner didn't seem to charge at all so I took my alternator in and the parts store tested it bad at about 10 volts. They gave me a new one and I made them test it before I took it. Tested perfect at 15v.

I took my 4runner out yesterday and it seemed to get harder and harder to start every time I went somewhere. I went to the mall about 20-25 miles away and when I got off of the freeway it was running like crap and soon stalled out.

I got it jumped and it started right up.

Parked it in a legal spot and turned it off and the battery was dead. I take the battery out and take it to the parts store where they test it and charge it and say it's good.

I replaced a crappy battery terminal thinking that may have been the reason it was doing this.

I drive it back to my dad's house about 20 miles from the mall and everything seemed fine.

Loaded the kids up and headed home and the head lights started to dim and it died at a red light. Got it pulled off the road and tried to start it again and it just clicked so I called roadside assistance. After about 5 minutes of sitting there I tried to start it again and it started right up. Drove it another 5 miles down the road to my house and it started to die again the same way but managed to get it all the way back.

So I charged the battery last night and took the 4runner to auto parts store and their charging system test didn't find the alternator. I took it back home and pulled off the alternator thinking the reman must have just gone bad. Took it back to the parts store and they tested it just fine at 15v on their bench rig.

I take it back home and toss it back in. Started it up off the battery and when the alternator terminal is disconnected from the battery, the alternator only shows 1.8v with the engine running.

With the alternator terminal connected the alternator always reads about 0.1 to 0.05 lower than the battery terminals. It is clearly not charging but seems like some voltage regulator issue. But the parts store tests it with the voltage regulator.

I did tear out my front harness and found some damaged wiring. I have repaired that thinking the whole time that it would certainly fix the problem and it did not...making me want to just set the thing on fire!

I have checked ALL fuses and fusible links. I have also doublechecked the backs of both of my fuse boxes and confirmed I don't see anything loose or disconnected.

What the hell could be going on with this?! Has anyone else had a problem like this that has just had a bad alternator no matter how well it tests at the parts store?

I'm ready to drive the damn thing and this is all that is holding me back.

The thing that really gets me is that I drove it a total of probably 30 miles with the headlights on and the parts store barely charged my battery.

PLEASE HELP ME!!!
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Old 04-18-2010, 01:49 PM   #2
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did you check your battery cables and their mounting points?
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Old 04-18-2010, 01:57 PM   #3
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Yes.

I've checked all of the battery wires. I have plenty of grounds from the battery. I have confirmed all of it is well attached to everything and that the wiring is in good shape. Like I said, I even replaced the battery terminal and the 80amp fusible link just in case.

The thing that gets me is, with the power terminal disconnected from the alternator, shouldn't the post on the alternator read 13-15v with the engine running? Because as I said, it only reads 1.8v. It seems to me that the voltage regulator isn't getting tripped to produce proper voltage but I don't know what the cause could be.
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Old 04-18-2010, 03:50 PM   #4
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I once bought a remanufactored alt. on my first 1986 truck and had the same thing happen to me. I went and pulled the back of the alt. cover off and found they FORGOT to replace the brushes. Put new factory ones in and it ran spot on. Might check to see how your brushes look. It's easy take off the back cover and in the center there will be a rubber "O" looking thing. Unscrew that and see how the brushes look?
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Old 04-18-2010, 04:28 PM   #5
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Yeah but would it produce 15v on the test bench?

Basically, I know what a voltage regualtor does but I don't know exactly how it is controlled via the vehicle. Should I be looking for other things on the vehicle that is suppose to tell the voltage regulator to pass through more voltage?

Another hint is that for unknown reasons, my fuel sending gauage, combination meter, temperature guage, and warning lights in my cluster do not work. Could this not working cause my alternator to not charge my alternator?

Forgive me for asking but what are the brushes in the alternator responible for?
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Old 04-18-2010, 04:48 PM   #6
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Belt slipping?
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Old 04-18-2010, 05:41 PM   #7
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nope...belt is very tight and does not whine or anything. Slipping belt or not, I can't see it producing only 1.8v.

Like I said, it seems like the voltage regulator isn't initiating charge despite it testing fine at the parts store.
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Old 04-18-2010, 07:09 PM   #8
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Here are some things to check

http://www.pirate4x4.com/forum/showt...tage+regulator
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Old 04-18-2010, 07:44 PM   #9
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I've already pulled my interior fuse panel and checked the backs of all of the connectors. Everything looked fine. I did have one problem with the connector for the main relay popping out but that was awhile go and has been repaired.
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Old 04-18-2010, 07:46 PM   #10
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One stupid question, if my charge light doesn't show up on the cluster, will this actually make my alternator not charge the battery? Or is this just "cosmetic"?
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Old 04-19-2010, 04:51 PM   #11
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the light in the dash is what starts the charging system up. it is the exciter circuit.try jumping 12v to the 7.5 fuse in the fuse box by the battery. it should charge until the motor is shut off. if it works the bulb needs changed.
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Old 04-19-2010, 05:05 PM   #12
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I took out my instrument cluster completely and replaced it with a custom one I made. The old cluster only had dummy lights, no gauges. All of the original wiring is hanging behind the new cluster and my charging system works fine. Only problem I ever had was a 15 amp fuse blew and my charging system quit, changed the fuse and everything has worked since. The EE's where I work looked at the diagram and said that the bulb doesn't need to be in the circuit for the alternator to charge. The only time that it is in the system is when the alternator fails and battery voltage is diverted to the light. Then again, they aren't always right.
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Old 04-19-2010, 05:08 PM   #13
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http://www.yotatech.com/f115/instrum...rnator-207547/
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