Alternator Problems

[Orkin]

I got a new (used) alternator because my current one had a strange problem where it would only "come on" once I got over 3000 RPM. Well, I put the newer one in the other day, and it doesn't charge. I took the alternator out of the car and took it to an alternator shop here in town, and they said it's charging fine. The guy said it must be a fuse or something.

So, thinking I had a bad connection I went ahead and reinstalled it, but I'm still getting nothing out of it. I'm not sure what fuses to check.

Checking voltage on the battery gives the same reading as checking it at the alternator post with the engine on or off. There's about 8 Ohms resistance between the alternator post and the positive battery terminal, but that shouldn't be enough to stop it...should it?

If anyone has any ideas for what else to check, please tell me!

Thanks in advance,
Jonathan

 

[Orkin]

I did some more investigation following Ford's charging system testing instructions, and I found that there appears to be a problem with the "I circuit", as there as no power to the I pin on the alternator connector with the key in the "Run" position. I also get no battery light, which also points to the "I circuit".

My question is, how do I check and service this circuit? Where does the wire at the other end of the "I" pin connect to?

Please help!

 

[SHOZ123]

The I circuit flows from your ignition switch in run to the light on the dash where there is a resistor in parallel to the alternator.

http://shoforum.com/diagrams/1993/9305.pdf

From another thread on another forum explaining how the battery light works.

Voice 1:
Looking at the schematic the green wire should be the ground for the batt light, there for should NOT have any voltage on it, so either the green wire is shorted to ground between the instrument cluster and the alt, or the alt/volt regulator is defective.
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Voice 2:
According to the diagrams I am looking at, there should be 12V there, with the key on and the wiring connector unplugged. The light is connected to 12V on one side (when the key is on), and the alternator grounds the other side to turn it on.
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Voice 1:
12v on the fuse side, and it should be 0v on the alt side, that's what makes the light come on. If it's 12v on the alt side then the light will remain off.
So either the wire is shorted to ground or the alt is grounding that wire
I suppose the cluster could have a problem in the printed circuit, but that would fall into the bad wire category.
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Voice 2:
It's 12V at the wiring connector any time the light is off but the key is on. Key on, engine off and wiring connector disconnected is how I would check the warning circuit. And using a voltmeter, not a test light.
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Voice 1:
Voltage drop the wire with it CONNECTED test the voltage before and after the bulb, leave it all hooked up, if you have 12v on both sides, then all is good and the light is off, if you get 0v on the alt side engine running, then ya got problems as mentioned before.

 

[Redskull]

from the battery to the Engine Compartment Fuse Box
Fuse #1 (IGN SW/BLW MTR) to the Ignition Switch
Ignition Switch: (B5) to (I1) in 'run'
from (I1) on I/S to to the Instrument Cluster
From the instrument cluster to Pin 'I' on the Regulator

The light has a alternite path resistor, so if it burns out, you'll still have a path
Test the light by jumpering the 'I' pin to ground and turning the key to run

 

[Orkin]

Thanks for the replies. I think I'm started to figure out what's going on here. I've read elsewhere that the I circuit is used to:
A) Activate the regulator
B) Control the battery light

As I'm not getting the 12V from the I pin on the regulator plug that I'm supposed to, it looks like both the resistor and the bulb have burned out, causing the regulator to stay in an "off" state, not allowing power to leave the alternator.

Does this this seem like a possibility?

 

[Orkin]

After 3 hours of completely disassembling my dash and tracing wires back and forth under my hood, I finally found that my battery light had in fact gone out, and that the fault in my I circuit was right at the alternator plug. I picked up a new plug and light at O'Reilly, but it was getting dark so I closed up before putting everything back together.

Hopefully this is the source of my trouble and I can finally put an end to my charging problems!

 

[Orkin]

I put in the new light, the new plug, and closed everything up today. The alternator puts out 13.3V right after starting up now! No more having to rev the engine every time I start the car to "turn on" the alternator!

The only problem is, there's a whine coming from the alternator, kind of like the interference an alternator puts into your stereo system, but much louder and it's audible from the engine bay. Anyone know what could be causing this?

 

[hawkeye18]

whines usually mean one of two things; either your idler pulley (right next to the alternator) is failing (more common) or your alternator pulley is failing (less common). Check the idler pulley first.