"generator" light stays on while engine is running....

[fussfeld]

My "generator" (battery) light now stays on while the engine is running. (the red warning light that has the icon of a battery, but the owner's manual calls this a "generator light")

1) this light glows at, i think, 1/2 the intensity of the other warning lights---brake, choke, oil etc. So it actually may have started yesterday during the day, but i did not detect it until last night when it got dark outside. As far as i know this light situation started yesterday.

2) the only differences i notice are that the left turn signal is a little slower than normal and the dash lights are dimmer than normal. Everything else, including headlights seem normal. And the truck starts and runs no problems.

3) New AC delco 321-357 alternator installed about 2 weeks ago. Belt is tight and new.

4) Battery should be good as i tested it before and during the alternator changeover. But i have tools and can test again.

 

[CorvairGeek]

Unfortunately, this is a common type of failure on this series alternator. It cannot charging at its full 63-78 amp rating due to a failure in the rectifier (IIRC). It is still charging, as long at the light isn't on at full brightness when running. You may even see it dim more, or even go out and fully charge (at least as much as needed) at times.

The good news is, I've seen people run them like this for years, but I wouldn't suggest it. Hopefully, you can take advantage of the warranty.

 

[fussfeld]

Battery is 12.5 and after i started it up.....no increase in voltage.


Next?

 

[gmachinz]

Battery is 12.5 and after i started it up.....no increase in voltage.


Next?

Alternator should be about 14.4V running-amperage output can vary-if you're getting 12.5 @ the alternator output post something isn't right with it.

 

[Georgeb]

What do you get if you ground to the alternator case rather than the battery and measure the voltage at the alternator output post?

 

[fussfeld]

What do you get if you ground to the alternator case rather than the battery and measure the voltage at the alternator output post?

With engine off 12.4 and with engine running, no change

 

[CorvairGeek]

This sounds completely inop, not at all like I was expecting

 

[Camar068]

2) the only differences i notice are that the left turn signal is a little slower than normal and the dash lights are dimmer than normal. Everything else, including headlights seem normal. And the truck starts and runs no problems

Almost sounds like you've got a heavy load on the dash/blinker ckt. Could be a bad ground. Try no key in ignition and turn on the hazards. Does your blinker speed change? It doesn't make sense that the left would be slower than the right.....they use the same flasher to run both correct?

This doesn't explain why your only seeing 12.5V though. Your right Corvair, measuring from the case of the alternator to the post on the alternator should read voltage output. I'm asking Corvair this question, is there any harm in disconnecting the wire from the alternator and measuring it without a load (battery) on it? If it reads 14.5'ish then it's something on the truck that's drawing it down (battery?)?

 

[Camar068]

do you have an ohm meter (omega symbol)? Not sure if you know how to use one so quick tutorial. Turn the meter on and put the leads together, it should read zero or darn near close to it. What you've done is tested the meter and it's leads. Anything but close to zero, you've got a blown fuse or bad leads. NEVER USE THE OHM METER ON ANYTHING WITH POWER....YOU'LL BLOW THE FUSE AND CAUSE U TO CHASE YOUR TAIL ON A PROBLEM THAT DOESN'T EXIST

With engine off, disconnect both positive and negative from the battery. Now put one lead on the negative battery cable and one on the alternator housing. You should read close to zero ohms. If your reading is other than that, shake the negative wire a bit and see if it changes. It helps at times to have clips on your leads or a second pair of hands. If it changes, you've got a loose connection or bad wire. Do the same for the positive wire, except now go to the positive wire going into the alternator.

Again no offense if you know how to use a meter. The ohm function can be very helpful, but you have to make sure you don't have power in the ckt. It's also a good idea to frequently touch your leads together to make sure the meter/leads are good as mentioned above. I chased my tail a few months ago because I didn't test it. Would have saved me 10 minutes troubleshooting.

 

[CorvairGeek]

Almost sounds like you've got a heavy load on the dash/blinker ckt. Could be a bad ground. Try no key in ignition and turn on the hazards. Does your blinker speed change? It doesn't make sense that the left would be slower than the right.....they use the same flasher to run both correct?

This doesn't explain why your only seeing 12.5V though. Your right Corvair, measuring from the case of the alternator to the post on the alternator should read voltage output. I'm asking Corvair this question, is there any harm in disconnecting the wire from the alternator and measuring it without a load (battery) on it? If it reads 14.5'ish then it's something on the truck that's drawing it down (battery?)?

Disconnecting the battery in operation is supposed to be a no-no. Damages the alternator with the sudden loss of the battery in an attempt to bring the voltage back up.

 

[Camar068]

Disconnecting the battery in operation is supposed to be a no-no. Damages the alternator with the sudden loss of the battery in an attempt to bring the voltage back up.

Good to know, Thanks

 

[fussfeld]

This sounds completely inop, not at all like I was expecting

Well first, let's backup and examine the question, "What do you get if you ground to the alternator case rather than the battery and measure the voltage at the alternator output post?"

The way i understood this was, i took the red lead from the meter and touched it to the B+ terminal on the alternator and then took the black lead and touched it to the alternator's body. With then engine off, i got 12.4---same as the battery which made sense to me since the alternator is connected to the battery and the alternator is grounded?

 

[fussfeld]

do you have an ohm meter (omega symbol)? Not sure if you know how to use one so quick tutorial. Turn the meter on and put the leads together, it should read zero or darn near close to it. What you've done is tested the meter and it's leads. Anything but close to zero, you've got a blown fuse or bad leads. NEVER USE THE OHM METER ON ANYTHING WITH POWER....YOU'LL BLOW THE FUSE AND CAUSE U TO CHASE YOUR TAIL ON A PROBLEM THAT DOESN'T EXIST

With engine off, disconnect both positive and negative from the battery. Now put one lead on the negative battery cable and one on the alternator housing. You should read close to zero ohms. If your reading is other than that, shake the negative wire a bit and see if it changes. It helps at times to have clips on your leads or a second pair of hands. If it changes, you've got a loose connection or bad wire. Do the same for the positive wire, except now go to the positive wire going into the alternator.

Again no offense if you know how to use a meter. The ohm function can be very helpful, but you have to make sure you don't have power in the ckt. It's also a good idea to frequently touch your leads together to make sure the meter/leads are good as mentioned above. I chased my tail a few months ago because I didn't test it. Would have saved me 10 minutes troubleshooting.

No, that's ok. i really don't know much about electricity/ electrical tools. Don't fear it, just never got around to it. Although it looks like i am going to HAVE to get around to it now........

 

[Camar068]

The way i understood this was, i took the red lead from the meter and touched it to the B+ terminal on the alternator and then took the black lead and touched it to the alternator's body. With then engine off, i got 12.4---same as the battery which made sense to me since the alternator is connected to the battery and the alternator is grounded?

That means your alternator is grounded and your positive wire to battery is good. Did you get your alternator locally new? I'd drive it down there and have them test it, or just swap it out in the parking lot and check your charge voltage while it's running.

Good video I found on youtube with him working with a meter. The test he does at about 10 minutes in is another way to verify you have good connection on your positive and negative wires.

https://www.youtube.com/watch?v=nQysE2oJAuo

 

[fussfeld]

UPDATE for saturday 2/25:

Ok, i test lighted both wires in the plug with the ignition on; Both wires have power, but the smaller brown wire is dimmer than the larger red wire.

So, i used the voltmeter; The larger red wire has 12.4-8 ish while the smaller brown wire, 6.3-5 ish.