Hello everyone,

I'm kind of stuck. A few weeks ago, I was driving my Chevelle down the freeway and lost power...not throughout the entire car, just like the coil wire popped off. So I thought that my kill switch was bad, so I by passed it. Then it ran...but then all the sudden it stopped again, so I put my coil power wire(a seperately ran one, not stock wiring harness) to another post on the fuse block, fired right up and got home. So then I cleaned the terminal on the fuse block where I originally had the power wire, boom it starts right up. But then I notice when the key is in the off postion, the generator light is on. If I turn the key to the 'on' position, it goes off...even though the engine isn't running. I was pretty frustrated at this point, so I disconnected the battery and went inside. When I disconnected the battery, I heard the horn relay kick off...

Fast forward to today. I unplugged the engine and forward lamp harnesses from the fuse block, sprayed it all out with brake cleaner, scrubbed with a brush, die-electric greased it, and I still have the same problem. If I disconnect both of the harnesses from the fuse block, and reconnect the battery, the gen light is off, but I can hear the horn relay kicking on....

I would think that with those harnesses disconnected the horn relay shouldn't get any power, right?

I'm pretty lost at this point as to where to look for problems. Any suggestions/comments would be greatly appreciated!! Thank you so much-

For now, I'm going to study the wiring diagram and see if I can see anything.

Hello Everyone,

I'm still having problems. I just replaced the ignition switch, as somebody had suggested that, and nothing happened. The Generator Light is still on when the key is in the "off" position, and turns off in the "on" position whether or not the car is running. The Gen Light stays on in the ACC position also.

I'm at a loss as what I could try to check/fix/replace.

How does the Generator light work? I'm guessing it has something to do a ground....

Can somebody give me some suggestions???

Thank you!

so I put my coil power wire(a seperately ran one, not stock wiring harness) to another post on the fuse block, fired right up and got home. So then I cleaned the terminal on the fuse block where I originally had the power wire, boom it starts right up. But then I notice when the key is in the off postion, the generator light is on. If I turn the key to the 'on' position, it goes off...even though the engine isn't running.
First, disconnect this wire, does the GEN light go off? What type of charging system do you have, externally regulated (which is original) or internally regulated? If you can't tell the difference see here (http://www.chevelles.com/forums/showthread.php?t=105661).

I was pretty frustrated at this point, so I disconnected the battery and went inside. When I disconnected the battery, I heard the horn relay kick off...
Are you sure its the horn relay? The voltage regulator (on externally regulated charging systems) near the same location.

I would think that with those harnesses disconnected the horn relay shouldn't get any power, right?
The horn relay is near the main electrical junction. On the 2 lage wires on the horn relay, one comes from the main splice, the other goes to the dash which feeds everything except the starter. See pic below

http://www.chevelles.com/showroom/data/500/medium/Original_Chevy_system.jpg

How does the Generator light work?
This is how it works on externally regulated charging systems.......

The regulator brown #4 wire is connected through the light bulb to 12V whenever the key is in the ON position. The other end goes through a set of points in the regulator and then out the F terminal to the field winding in the alternator. So some current begins flowing in the field winding from this connection. The little bit of current flowing produces a weak magnet field in the alternator and also lights the bulb.

When you then start the car, the weak magnetic field from above begins rotating which makes the alternator producing a little bit of voltage. This voltage is fed from the alternator to the regulator on the white regulator #2 wire. This wire connects to a coil in the regulator and turns on a contact when the voltage goes above 3.2V. Once the contact turns on in the regulator the #3 and #4 terminals are connected together. Terminal #3 is battery power so this puts battery power on both sides of the bulb and turns it off. This means the brown #4 wire should go to +12V. Also, this connects the field terminal right to battery power but still going through the points.

Thanks so much for the reply, which helps me a lot. I double checked this morning, and it is actually the voltage regulator that is clicking when connected/disconnected to power, NOT the horn relay. Last night after I had replaced the ignition switch, I started the car up just because it had been a few weeks…the alternator IS charging. Also, with the car running, the generator light is off, but remember it’s off when the key is in the ‘On’ position regardless if the engine is running. The car was updated to an internally regulated alternator. I also disconnected the coil power wire at the fuse block, and it made no difference with the generator light.

To me it sounds like I have two different issues. One being my fuse block/coil power wire, which seems to be fixed. The other is the generator light situation.

So what do you think might be causing my problem, a faulty voltage regulator??? It might just be a coincidence that I had both problems at almost the same time.

I started the car up just because it had been a few weeks…the alternator IS charging. Also, with the car running, the generator light is off, but remember it’s off when the key is in the ‘On’ position regardless if the engine is running. The car was updated to an internally regulated alternator. I also disconnected the coil power wire at the fuse block, and it made no difference with the generator light.
Was the battery connected during these few weeks? Are you sure its charging? What is the voltage, at the battery, with the car running at a fast idle?


So what do you think might be causing my problem, a faulty voltage regulator??? It might just be a coincidence that I had both problems at almost the same time.

With the key off, disconnect the 2 small wires at the alternator, the GEN light should turn off. If it does, test for power at terminal 1 at the alternator (there are markings on back of alternator) If there is power, VR is bad.

Greg, Thanks again for all the help.

So here's what I came up with after my tests tonight.

The alternator is definitely charging at the battery. It's around 14 volts.

I disconnected the two wire plug, and the gen light went off. When I turned the key to the 'On' Position, it went back on, like it should.

While the plug was disconnected, I took a test light and hit the four different posts on the alternator, which one is labeled Batt, The two wire plug, and another post labeled Ground. The test light came on when touched to batt, and on the two wire plug, the one labeled 'R.' The other one is labeled 'F.' The R wire is yellow, the other blue I believe.

A couple other observations were made. After I started it, while checking to see if it was charging, it ran for about 2-3 minutes tops. Right after that I touched the alternator to get to that plug, and it was really hot! Almost too hot to touch. That doesn't seem normal to me.

Another observation....I had the battery's negative disconnected, but I had my test light clipped onto the negative on the battery. I touched it to the positive charging wire on the alternator, and it lit up. But then I touched the test light to the actual alternator, and it lit up, and I could hear the voltage regulator click on! I then touched the voltage regulator to the valve cover and then the frame, all with the same results; test light coming on, and voltage regulator coming on. I disconnected the harness from the voltage regulator, and it stopped doing this. This tells me I have a short somewhere right??? But would it be in the two wires from the alternator to the voltage regulator, or from the voltage regulator to the key? Or would it be a bad alternator or voltage regulator???

I'm so lost. :(

One more thing...

My buddy Tom suggested to jump the external regulator, to see if that does anything. So I took off the plug, jumped 1 to 3, and 2 to 4...it did nothing. The gen light came on, then went off when the key is turned to the 'on.'

Would you think this leads to a faulty alternator????

Greg, Thanks again for all the help.

So here's what I came up with after my tests tonight.

The alternator is definitely charging at the battery. It's around 14 volts.
What kind of meter are you using? Are you sure it is accurate? What does the meter read just on the battery with car not running?

I disconnected the two wire plug, and the gen light went off. When I turned the key to the 'On' Position, it went back on, like it should. It should have stayed off if you have a properly wired internally regulated alternator.

The car was updated to an internally regulated alternator.
Are you sure its a internally regulated alternator? Internally regulated alternators have the 2 small terminals like this -- externally regulated alternators have the 2 small terminals like this l l See pics below. Also if internally regulated, the external voltage should have been bypassed.


http://www.chevelles.com/showroom/data/500/DSC00320.JPG
http://www.chevelles.com/showroom/data/500/Dsc00886.jpg

Above pics are a externally regulated alternator, they usually just have "R" and "F" markings for the small terminals


http://www.chevelles.com/showroom/data/500/DSC00322.JPG
http://www.chevelles.com/showroom/data/500/Alternator1.jpg

Above pics are a internally regulated alternator, they usually have just "1" and "2" markings for the small terminals


The other one is labeled 'F.' The R wire is yellow, the other blue I believe.

The "F" wire is blue, the "R" wire is white, although they turn yellow with age.

A couple other observations were made. After I started it, while checking to see if it was charging, it ran for about 2-3 minutes tops. Right after that I touched the alternator to get to that plug, and it was really hot! Almost too hot to touch. That doesn't seem normal to me.
Was the battery fully charged? Hot alternators usually mean its near max output, usually from a low battery, or overcharging

Another observation....I had the battery's negative disconnected, but I had my test light clipped onto the negative on the battery. I touched it to the positive charging wire on the alternator, and it lit up. But then I touched the test light to the actual alternator, and it lit up, and I could hear the voltage regulator click on! I then touched the voltage regulator to the valve cover and then the frame, all with the same results; test light coming on, and voltage regulator coming on. I disconnected the harness from the voltage regulator, and it stopped doing this. This tells me I have a short somewhere right??? But would it be in the two wires from the alternator to the voltage regulator, or from the voltage regulator to the key? Or would it be a bad alternator or voltage regulator???

I'm so lost. :(

If externally regulated, make sure the voltage regulator is well grounded, and you also have the small wire ground to the fender. If you have a internally regulated alternator, bypass the voltage regulator, see pic below.

http://www.chevelles.com/showroom/data/500/new_alternator_wiring_pic2.JPG

One more thing...

My buddy Tom suggested to jump the external regulator, to see if that does anything. So I took off the plug, jumped 1 to 3, and 2 to 4...it did nothing. The gen light came on, then went off when the key is turned to the 'on.'
If you did this and the alternator is externally regulated, it puts straight battery power to the "F" terminal which forces the alternator to max output. (field testing)

I started the car up just because it had been a few weeks
I ask again, was the battery connected during these few weeks? Your tests indicate a power drain which would made the battery go dead sitting for a few weeks.

I used a load tester last night, as my digital voltmeter died. Plus I have a volt gauge that’s hooked up to the car, but it’s connected to the fuse block. The battery read around 12.5 volts with the car turned off, but everything hooked up. I didn’t check the reading with the ground disconnected. The battery is about 1 month old.

Just for clarification, when I disconnected the two wires from the alternator, the generator light did go off, with the key in the ‘off’ position. I turned the key to the ‘on’ position, and the light came on, like it normally would. I didn’t start the car though to see if the light would go off.

I had just assumed(I know, I know) that it was an internally regulated alternator, since it wasn’t the stock generator. However going off your description( - - and l l ), plus the pictures, it looks like mine is an externally regulated. I snapped a few pictures of it.

http://i157.photobucket.com/albums/t43/Bad66Chevelle454/Alternator001.jpg

http://i157.photobucket.com/albums/t43/Bad66Chevelle454/Alternator002.jpg

http://i157.photobucket.com/albums/t43/Bad66Chevelle454/Alternator003.jpg

This is the alternator that was in the car when I bought it…I haven’t touched the electrical under the hood in the car since I bought it.

The battery was fully charged…however, it got me thinking. My car has an air ride set up on it, and while it was running I flipped on the air compressor, which really taxes the charging system, especially at idle. When I got my reading though, I made sure the compressor was off. So perhaps that max output for those few minutes could of made it that hot.

When I by passed the voltage regulator, I didn’t start the car. I just by passed it, hooked the battery back up, and saw the Gen light was on with the key in the ‘off’ position, and then turned the key to the ‘on’ position and the light went off, like it has been doing. Since this bypasses the voltage regulator, wouldn’t that indicate either a short in the line somewhere, or a short in the alternator?

When the car was sitting for those few weeks, the battery was disconnected. I saw that the Gen light was on, and I knew that would drain the battery, so I disconnected it and walked away.

I brought the alternator to work, and I was going to run to Napa after work and have them test it, plus see if they have a new one. I was thinking maybe just buy a new one to completely eliminate that possibility? I could also unravel the wiring harness that has the two wires that go to the alternator to see where they go…

Thanks again for your help!!!

I had just assumed(I know, I know) that it was an internally regulated alternator, since it wasn’t the stock generator. However going off your description( - - and l l ), plus the pictures, it looks like mine is an externally regulated. I snapped a few pictures of it.
Yes, its externally regulated.


The battery was fully charged…however, it got me thinking. My car has an air ride set up on it, and while it was running I flipped on the air compressor, which really taxes the charging system, especially at idle. When I got my reading though, I made sure the compressor was off. So perhaps that max output for those few minutes could of made it that hot.
Was the most likely cause.


When I by passed the voltage regulator, I didn’t start the car. I just by passed it, hooked the battery back up, and saw the Gen light was on with the key in the ‘off’ position, and then turned the key to the ‘on’ position and the light went off, like it has been doing. Since this bypasses the voltage regulator, wouldn’t that indicate either a short in the line somewhere, or a short in the alternator?
No. The GEN light goes off by applying power to both sides of the bulb. When the key is on, power comes the IGN switch. When the key is off the should be no power at GEN light. I just reread one of your earlier posts, guess I missed that one......
The test light came on when touched to batt, and on the two wire plug, the one labeled 'R.

There should be no power at the "R" terminal with the engine not running...

These are readings from the voltage regulator, with wires still connected....

From the above (KOEO = key on engine off and KOER = key on engine running).
F or #1 terminal (field) - KOEO = #4 slight voltage, KOER = 9-12V typically
#2 terminal (sense) - KOEO = 0V, KOER =3.2V
#3 terminal (Battery) - KOEO = 12V, KOER = 12V
#4 terminal (light) - KOEO = F slight voltage, KOER = 12V

By 12V above I mean battery voltage, which may be 12V when engine is off but could be up to 14.5V when engine is running.

When the car was sitting for those few weeks, the battery was disconnected. I saw that the Gen light was on, and I knew that would drain the battery, so I disconnected it and walked away.
Good
I brought the alternator to work, and I was going to run to Napa after work and have them test it, plus see if they have a new one. I was thinking maybe just buy a new one to completely eliminate that possibility? I could also unravel the wiring harness that has the two wires that go to the alternator to see where they go…

Thanks again for your help!!!
The 2 wires go to the voltage regulator, terminals "F" and 2


Personally, if you have to buy anything, I would convert to a internally regulated alternator. You can buy a kit do do this or make jumpers at the VR, and change the plastic plug for the 2 small wires. (I can post part#s and where to get if interested) I would also get a higher amperage alternator since you have a air ride set up. ( I can post part#s and where to get if interested, post pics of your alternator mounted so the clocking will be correct)

If you want to keep the original set up, you will need a new alternator and maybe a new VR

This was written by another member, a very good write up on how it works and how to troubleshoot a externally regulated charging system.

I dug this out from before, hopefully it help. If not, just post or send me your questions.

I'll try to provide a simplified explanation of how the externally regulated alternator and regulator work here. This explanation starts from a parked car with engine off state.

The regulator brown #4 wire is connected through the light bulb to 12V whenever the key is in the ON position. The other end goes through a set of points in the regulator and then out the F terminal to the field winding in the alternator. So some current begins flowing in the field winding from this connection. The little bit of current flowing produces a weak magnet field in the alternator and also lights the bulb.

When you then start the car, the weak magnetic field from above begins rotating which makes the alternator producing a little bit of voltage. This voltage is fed from the alternator to the regulator on the white regulator #2 wire. This wire connects to a coil in the regulator and turns on a contact when the voltage goes above 3.2V.

Once the contact turns on in the regulator the #3 and #4 terminals are connected together. Terminal #3 is battery power so this puts battery power on both sides of the bulb and turns it off. This means the brown #4 wire should go to +12V. Also, this connects the field terminal right to battery power but still going through the points.

When the battery voltage goes above a set level, the F terminal is disconnected from the battery power by the points I kept mentioning. Then the voltage drops and the points close again. This on-off cycling happens rapidly and is how the voltage gets regulated.

From the above (KOEO = key on engine off and KOER = key on engine running).
F or #1 terminal (field) - KOEO = #4 slight voltage, KOER = 9-12V typically
#2 terminal (sense) - KOEO = 0V, KOER =3.2V
#3 terminal (Battery) - KOEO = 12V, KOER = 12V
#4 terminal (light) - KOEO = F slight voltage, KOER = 12V

By 12V above I mean battery voltage, which may be 12V when engine is off but could be up to 14.5V when engine is running.

Check the light: Ground the brown #4 terminal wire at the regulator. When grounded the light should come on. If you don't have a light then skip this test. Test this with the connector off the regulator.

Checking the alternator: Jumper the blue wire F terminal to the battery post on the back. This should make it easily crank out 16+ volts. Next, connect a troublelight between the battery post and the F terminal. The light should come on and you should measure > 3.2V at the other alternator terminal. If it passes these tests, then it's in the regulator or wiring.

Checking the wiring: At the regulator connector jumper the brown light wire (#4) to the F terminal (#1) and you should be able to measure >3.2 volts on the other alternator terminal or terminal #2 of the regulator connector. If these tests pass, it is in your regulator.

When doing these tests, make sure you turn off or pull the fuses for any added electronics that you can. The alternator test can produce enough voltage to damage stuff.

Peter

Greg,

I stopped by Napa and got a new alternator. Popped it in, and it fixed all my problems and works perfect. It charges like it actually should...the old one charged, but not as well as it should have.

I agree that upgrading the alternator to an internal regulated version is the best way to go....but for now, it was a cheap and easy fix for me. I'll get around to upgrading everything someday under the hood.

Thanks again for all your help...you don't know how much I appreciated it!!!