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Driving home last week I look down and my volt meter is up around 17 and my little red light is on. I have no choice but to drive another 7 miles. I turn everything on. High beams, heater, rear defrost and keep the RPM’s low and the voltage hovers around 15. I go get an a new alternator. They test my old one and say it’s bad, overcharging. Put the new one in and now I’ve got two more lights on the dash on and the thing won’t charge. I’ve got 12 volts at the exciter wire when the key is on. I take the ring terminal off the alt and put my meter on the stud. 17 volts and as I rev the motor it goes up to over 20. I go get ANOTHER alternator and it does the same thing. I even ran a wire for the exciter from the battery and ran a wire directly to the battery eleminating the harness. Still won’t charge. They gave me quite a bit of grief on bringing the first one back. Should I try getting another one? EA81 with a Webber. All stock untouched wiring. Oh and I pull the charging fuse and the lights go out but still won’t charge

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check the white/red wire at the alt terminal for good connection.

 

never run the alt with no wire connected to the main output.  Could have fried it right there.

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When everything is connected what is the reading at the battery? Could be that the battery is bad now and not taking a charge.

It does sound like a faulty alternator though...someone correct me if i am wrong but the kind subes use have internal voltage regulators that will keep the voltage at around 14 volts with the engine spinning 750 rpm to whatever rpm you care to rev?

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Do not run an alternator without a battery.

 

Somewhere near 14v should be normal when charging.

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Dead fusible link?

 

I can't remember if the charge wire goes through the fusible link. The reference wire certainly would. I'd be checking these to ensure they're all in good health.

 

Cheers

 

Bennie

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Yes, charging current goes through one of the fusible links.  Otherwise, a rectifier failure could cause a fire from unlimited battery current traveling back into the alternator.

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Fusible links are good. 12v on both sides of all 3. Even ohmed them to make sure. It’s an 82 model. The alt I git is internally regulated. Where would the regulator be if it was external?

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1.3 volts at the white w/red, white has 12v big wire has 12v when running. Gauge shows 9ish and the terminal on the back of the cluster at the volt meter is the same when engine is running.

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Maybe the overcharging damaged something?

 

overcharging XT6 alternator blew light bulbs, black fusible link, igniter, flasher/blinker unit, and the TCU.

 

I noticed symptoms for about 1 minute (bright lights and fluctuating lights).

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12v while running indicates no or low output from the alternator. The battery is supplying power.

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Other than the fusible links on the pass fender is there any others that I don’t know about??

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Just a thought:  Run a new wire directly from the alternator output terminal to the positive post.  Fuse the new circuit. Thinking the problem may be all the wiring under the fusible links box. 

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Had the alt tested and watched them test it. 15.4v. Ugh! Ran a wire from the alt to the battery, another from the exciter wire to the battery. Two more for the coil and fuel pump. Then I jumped the starter to fire it up. STILL not charging.

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Had the alt tested and watched them test it. 15.4v. Ugh! Ran a wire from the alt to the battery, another from the exciter wire to the battery. Two more for the coil and fuel pump. Then I jumped the starter to fire it up. STILL not charging.

 

Almost sounds like the belt is not spinning the alternator. Does this car have a 2-piece front balancer? 

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Almost sounds like the belt is not spinning the alternator. Does this car have a 2-piece front balancer?

Great call - separated crank pulley. Edited by idosubaru

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I think I’m getting closer. The two pin plug on the back of the Alt has 12v at the white and 1.7 at the white w/red. Shouldn’t they both be 12v when the car is running???

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You said if you pull the fuse the alternator light goes out? I would check wiring at the fuse block. Mine was a combination of things not charging. First I had to fix the short on the fuse block. Next I had to repair fusible link box which means special wiring tools( it's a sob to do, thanks Dave T for guidance) next I had to replace bad alternator and all wiring to do with charging system (30 years in Phoenix az= crispy). Then I read a very common problem which sealed the deal, ground straps from engine to chassis! All in all my car not being grounded caused major problems and helped fry a lot of components and even did damage to the heads= electrolysis. My gauge doesn't work from the factory since I fried it, but my AutoZone special Cheapo gauge matches my dvom outputs 100%. Hope some of this can help

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My wiring is really good and nice still. Still had the ground wires and the first thing I did was clean all the connections. I’m trying to track the wire from the alternator to the fuse under the dash then where it goes after that. I have 12 at it with the fuse out then it drops to 1.7 when the fuse is installed.

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Seems like a FSM schematic would be helpful at this point.
Unfortunately, I only have EA82s.

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Charge light still work?

 

Alternator won`t get any intial field current if the bulb blew.

 

FYI,FSM charging system schematics are nearly useless.

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