# Pontiac 1968 GTO problem, Gen indicator light stays on



## Nummy22 (Sep 7, 2010)

First thing I checked was the connections on the alternator. To see if the Generator light would go out but it didn't. Then I bought a rebuilt new working alternator. Installed it. And the Generator light is still on.

Checked the battery connections also, don't know if its tight enough still though. I'm also wondering if it is the battery connections. Like say if it's connected correctly, but it's not on tight enough, and it can still turn on, then can the generator light still turn on due to it not being tight enough and still work?

Or if it could be a bad voltage regulator. If there is even is one? Or is that in the alternator itself?


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## jetstang (Nov 5, 2008)

Yes, it could be a bad regulator, or a bad plug in connector on the back of the alternator. Use a load tester, charger or multimeter and check the battery voltage to see if the alternator is putting out voltage, when running it should be over 13 volts, or a higher voltage than when not running. Is the battery going dead? You can also disconnnect the battery hot and see if the car stays running, if it stays running, the alt is putting out voltage.


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## Eric Animal (Oct 28, 2007)

If the car has been converted to a SINGLE WIRE ALT with built in regulator, this could cause the problem also....there are 2 wires to the Alt light. 1goes to the #1 terminal on the ignition switch,along with the other "idiot lights". The other wire goes through the fire wall connector, to the #4 terminal io the regulator (black box on fire wall)....if this connection is weak,faulty bad regulator, poor dash ground, bad alternator, you will get a light on. :cheers E


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## Nummy22 (Sep 7, 2010)

Yeah, I just found out. Problem was is that the alternator I replaced apparently had a voltage regulator inside of it. And this new one doesn't. So I need to buy an external voltage regulator.

But can the work without a voltage regulator?


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## Nummy22 (Sep 7, 2010)

I got it to work. The gen light went out. There is a regulator box.

I looked at the wiring chart that came with the new alternator. And I hooked it up by what it says under W/Gauges.

F on the alternator is suppose to go to F on the regulator. And that worked. And there wasn't suppose to be on any wire on R.

Out of curiosity, there was a chart that says W/indicator lamp. What is a indicator lamp system? I don't think my car has that.

Nothing came up in the manual either.


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## aggie88 (Aug 13, 2005)

Good timing (or bad?) I have the same problem with my 70. I did not change the alternator. I believe it has an external regulator. The gen light stays on in the key off position. But if I pull the battery and reconnect it after a while, the gen light is out. Fix?


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## Eric Animal (Oct 28, 2007)

Nummy-indicator light=GEN Light or ALT light.
Aggie- you might have a sticking regulator.


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## aggie88 (Aug 13, 2005)

Eric Animal said:


> Nummy-indicator light=GEN Light or ALT light.
> Aggie- you might have a sticking regulator.


I've got a brand new spare. Will pop it in. Thanks Animal!:cheers


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## Eric Animal (Oct 28, 2007)

Aggie, Please post the outcome! :cheers


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## Rukee (Feb 8, 2007)

Always replace the regulator anytime you replace the alt, and vise~versa.
And never buy the cheaper regulator, they rarely work right. Get the better one, it may cost more but it works.


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## Nummy22 (Sep 7, 2010)

Rukee said:


> Always replace the regulator anytime you replace the alt, and vise~versa.


Is there a reason for that? He was going to buy the regulator box also because the Gen light indicator was still on. But when he noticed he just had it hooked up wrong. There was no need to buy it. 

By the way, thanks for the help so far, everyone.


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## Rukee (Feb 8, 2007)

I recommend replacing both at once. It IS possible that a bad alt could burn-out a regulator, and a bad regulator could burn-out an alt over time. Better to just replace both and not risk it. IMO.


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## Eric Animal (Oct 28, 2007)

:agree Glad it all worked out. Another "famous saying".......


" If we built it, we can fix it."
- E. Animal


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## aggie88 (Aug 13, 2005)

Eric Animal said:


> Nummy-indicator light=GEN Light or ALT light.
> Aggie- you might have a sticking regulator.


Turned out the other regulator I had in my stock was the old original. But I swapped it in anyway. Did not fix the problem. The curious thing is, when I switch the ignition to the RUN position, the GEN light goes out. Probably a sticky ignition switch?


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## aggie88 (Aug 13, 2005)

Okay, today, after idling the car, I shut it down and started hearing the regulator vibrating. Then all hell broke loose.

The wires to the alternaotor started smoking! I yanked the negative cable as fast as I could. But I think most of the primary wiring from the switch down is fried.


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## Eric Animal (Oct 28, 2007)

It could be the REGULATOR. possibly the ignition switch. or a shorted wire somewhere in between. I think there are 3 wires from the reg to the ignition switch, see if anything under the dash fried, then check the ign.sw.. Maybe the old regulator was bad (2nd choice). You could have a short somewhere (3rd choice).


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