Gen light stays lit - Team Camaro Tech
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post #1 of 9 (permalink) Old Apr 26th, 15, 11:57 AM Thread Starter
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Gen light stays lit

I just installed a 100 amp alternator in my 67 RS now the gen light stays on when the car is running. Does anyone know if the stock type voltage regulator can handle the more powerful alternator? Should I have purchased a generator? Everything seems to be working fine except for the light. I have 12.7 volts at the battery with the car running at about 1100 rpm.
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post #2 of 9 (permalink) Old Apr 26th, 15, 12:35 PM
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Re: Gen light stays lit

Double check that you don't have the 2 wires at the plug backwards. Easy to do.
Also, with car running and alternator working, you should see 13.5-14v at battery.


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post #3 of 9 (permalink) Old Apr 26th, 15, 12:38 PM
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Re: Gen light stays lit

Is the new alternator an internally regulated type SI?
If so, you need to remove/unplug the OE regulator and jumper across the two inside wires and jumper across the two outside wires.

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post #4 of 9 (permalink) Old Apr 26th, 15, 12:54 PM Thread Starter
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The plug for the 2 wires fit right in. How would I know if they are reversed, and if reversed would it do any damage? The new alternator does not have an internal regulator.
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post #5 of 9 (permalink) Old Apr 26th, 15, 03:59 PM
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Re: Gen light stays lit

Your alternator is not charging properly if you are getting 12.7 V at the battery with the car running. Take the alternator to be tested or try with the old alternator. If it is charging 14V on the bench the regulator or poor connections would be the next thing I would look at. Make sure your grounds are clean and secure.

A picture might help.

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post #6 of 9 (permalink) Old Apr 26th, 15, 04:20 PM
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Re: Gen light stays lit

Quote:
Originally Posted by Rs67Rs View Post
The plug for the 2 wires fit right in. How would I know if they are reversed, and if reversed would it do any damage? The new alternator does not have an internal regulator.
It reads you have an 10DN alt, OE design - external regulated.

Alt two-wire plug, as you look at the rear of the plug connected, blue wire to right side, white wire to left side.

Old roadside trick, if you lay a screwdriver across the rear alt bearing, a working alt will generate a magnetic field and screwdriver will have resistance when pulling it away.

Other notes,
the regulator closes a relay internally to turn off GEN light if alt is charging.
Ensure reg has a ground strap from the chassis to the radiator support - OE design had a strap about a mounting bolt.
Ensure alt case has less than 1 ohm resistance to the reg chassis - might need to run a separate wire for ground as alt case must rely on mounting bracketry and hardware for path. If a lot of paint, conductivity is nil.
If you measure 3-5 volts on blue wire at alt wirth engine running at 2000 rpm, and less than 12.3 volts at BATT stud of alt, bad alt - open diode or worn brushes.

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Last edited by DOUG G; Apr 26th, 15 at 05:01 PM. Reason: 12.3....change it from 123 ;)
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post #7 of 9 (permalink) Old Apr 26th, 15, 05:59 PM Thread Starter
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Ok I'm out of town for a couple days. I will look into your suggestions when I return. Thanks for everyone's help.
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post #8 of 9 (permalink) Old Apr 26th, 15, 06:46 PM
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Re: Gen light stays lit

Thanks, Doug.

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post #9 of 9 (permalink) Old Apr 26th, 15, 07:17 PM
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Re: Gen light stays lit

I know....fat fingered it

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