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post #1 of 28 (permalink) Old Jun 28th, 10, 9:58 PM Thread Starter
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George
 
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Gen light question

Does this sound correct?

With the key on the GEN light is on....start engine GEN still on but not as bright.

Swapped Voltage Regulator (external on firewall). Now with the key on...GEN light is off...start engine...GEN light still off.

With engine running (800 rpm idle) There is approx 14 v at the battery and back of alt. Wire coming off the side of alt that runs over to Voltage reg is 12v.

Is this the way it should be?

Thank

My '71 Malibu:

355 9.7:1, Edelbrock Performer RPM heads and intake, Clay Smith hydraulic roller cam (280/294 .516 lift), Holley 650 DP, Pertronix ignition

TH350 Allstar 10" converter

12 bolt posi, 3.90 gears, MT ET Street DR 275/60/15

W/ 3.31's…...12.87@104
W/ 3.90's…...12.70@106
W/ 125 shot..11.85@112
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post #2 of 28 (permalink) Old Jun 28th, 10, 10:06 PM
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Randy
 
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Re: Gen light question

With external regulator, ignition on, not running, lamp should be on. Engine running, lamp should be off. If the lamp is burned out, the alternator will NOT charge the battery.

Randy
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Owning a Chevelle project is like having a giant-size piggy bank that you keep pouring money into....but you can't get it back out.
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post #3 of 28 (permalink) Old Jun 28th, 10, 10:13 PM
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Re: Gen light question

No, not right.

Gen light on with key in run position before starting engine. Gen light off after engine running. 14v at idle doesn't sound bad. 12v going from alt to volt regulator, which wire? Make sure voltage regulator is grounded to rad core support. Make sure it's a good clean connection. Make sure the forward light harness grounds to rad core support are clean and good connections. Also pigtail off negative battery cable to passenger fender. A bad ground will fool the Gen light circuit and cause the light to glow, been there before.

Hank

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post #4 of 28 (permalink) Old Jun 28th, 10, 10:15 PM
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Re: Gen light question

Quote:
Originally Posted by pnugene View Post
With external regulator, ignition on, not running, lamp should be on. Engine running, lamp should be off. If the lamp is burned out, the alternator will NOT charge the battery.
There is a resistor in parallel with the light bulb. If the bulb burns out the current flows through the resistor to field windings and the alt will still charge.

Hank

70 Chevelle SS396(454), M20, 3.73
My Chevelle
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post #5 of 28 (permalink) Old Jun 28th, 10, 10:24 PM
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Re: Gen light question

Quote:
Originally Posted by Finally View Post
There is a resistor in parallel with the light bulb. If the bulb burns out the current flows through the resistor to field windings and the alt will still charge.
Thanx for the correction. I built a homespun harness for my engine test stand and didn't know about the resistor. When my lamp got trashed the alternator quit charging. And I was thinking GM didn't cover their bases.

Randy
TC # 5401
67 Project SS Clone

Owning a Chevelle project is like having a giant-size piggy bank that you keep pouring money into....but you can't get it back out.
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post #6 of 28 (permalink) Old Jun 28th, 10, 11:42 PM Thread Starter
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George
 
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Re: Gen light question

Quote:
Originally Posted by Finally View Post
No, not right.

Gen light on with key in run position before starting engine. Gen light off after engine running. 14v at idle doesn't sound bad. 12v going from alt to volt regulator, which wire? Make sure voltage regulator is grounded to rad core support. Make sure it's a good clean connection. Make sure the forward light harness grounds to rad core support are clean and good connections. Also pigtail off negative battery cable to passenger fender. A bad ground will fool the Gen light circuit and cause the light to glow, been there before.
The gen light would come on with the key in the on position before changing the regulator. Now it won't come on. I know the bulb works (or at least did).

The 12 volt reading is on the blue wire that is spliced in with the white wire coming out the side of the alternator (small plug with two wires). It runs over to the regulator 4 pin connector.

I didn't change the little metal can that plugs in to the reg though.

I did add the neg battery pigtail yesterday.

My '71 Malibu:

355 9.7:1, Edelbrock Performer RPM heads and intake, Clay Smith hydraulic roller cam (280/294 .516 lift), Holley 650 DP, Pertronix ignition

TH350 Allstar 10" converter

12 bolt posi, 3.90 gears, MT ET Street DR 275/60/15

W/ 3.31's…...12.87@104
W/ 3.90's…...12.70@106
W/ 125 shot..11.85@112
Geo71 is offline  
post #7 of 28 (permalink) Old Jun 28th, 10, 11:43 PM Thread Starter
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George
 
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Re: Gen light question

Quote:
Originally Posted by pnugene View Post
With external regulator, ignition on, not running, lamp should be on. Engine running, lamp should be off. If the lamp is burned out, the alternator will NOT charge the battery.
The bulb did work unless it blew out for some reason.

My '71 Malibu:

355 9.7:1, Edelbrock Performer RPM heads and intake, Clay Smith hydraulic roller cam (280/294 .516 lift), Holley 650 DP, Pertronix ignition

TH350 Allstar 10" converter

12 bolt posi, 3.90 gears, MT ET Street DR 275/60/15

W/ 3.31's…...12.87@104
W/ 3.90's…...12.70@106
W/ 125 shot..11.85@112
Geo71 is offline  
post #8 of 28 (permalink) Old Jun 28th, 10, 11:49 PM
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Re: Gen light question

The new regulator may have failed if you ran it without the regulator ground wire.

Randy
TC # 5401
67 Project SS Clone

Owning a Chevelle project is like having a giant-size piggy bank that you keep pouring money into....but you can't get it back out.
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post #9 of 28 (permalink) Old Jun 28th, 10, 11:50 PM Thread Starter
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George
 
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Re: Gen light question

Quote:
Originally Posted by pnugene View Post
The new regulator may have failed if you ran it without the regulator ground wire.
Which wire is that? I hooked up the new one just like the old one.

My '71 Malibu:

355 9.7:1, Edelbrock Performer RPM heads and intake, Clay Smith hydraulic roller cam (280/294 .516 lift), Holley 650 DP, Pertronix ignition

TH350 Allstar 10" converter

12 bolt posi, 3.90 gears, MT ET Street DR 275/60/15

W/ 3.31's…...12.87@104
W/ 3.90's…...12.70@106
W/ 125 shot..11.85@112
Geo71 is offline  
post #10 of 28 (permalink) Old Jun 29th, 10, 7:49 AM
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Hank
 
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Re: Gen light question

Check the bulb. If you're reading 14v at the bat and alt while idling the alt is working. Run the engine up a little and see if the voltage goes up, shouldn't go up much, 14 to 14.5 is about right.

Hank

70 Chevelle SS396(454), M20, 3.73
My Chevelle
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post #11 of 28 (permalink) Old Jun 29th, 10, 8:54 AM Thread Starter
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Re: Gen light question

Quote:
Originally Posted by Finally View Post
Check the bulb. If you're reading 14v at the bat and alt while idling the alt is working. Run the engine up a little and see if the voltage goes up, shouldn't go up much, 14 to 14.5 is about right.
I'll check it out later today and see what i can find out. There were a couple wires that attached to the bolt closest to the headlight side. That wouldn't be a ground wire for that bulb would it?

Thanks for all your help! You are a lifesaver

Checked out your car pics....very nice!

My '71 Malibu:

355 9.7:1, Edelbrock Performer RPM heads and intake, Clay Smith hydraulic roller cam (280/294 .516 lift), Holley 650 DP, Pertronix ignition

TH350 Allstar 10" converter

12 bolt posi, 3.90 gears, MT ET Street DR 275/60/15

W/ 3.31's…...12.87@104
W/ 3.90's…...12.70@106
W/ 125 shot..11.85@112
Geo71 is offline  
post #12 of 28 (permalink) Old Jun 29th, 10, 12:13 PM
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Re: Gen light question

a bad connection at the alternator plugin will also cause the gen light to remain lit after the engine starts. been there; done that.
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post #13 of 28 (permalink) Old Jun 29th, 10, 5:54 PM
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Re: Gen light question

Quote:
Originally Posted by Geo71 View Post
I'll check it out later today and see what i can find out. There were a couple wires that attached to the bolt closest to the headlight side. That wouldn't be a ground wire for that bulb would it?

Thanks for all your help! You are a lifesaver

Checked out your car pics....very nice!
Thanks. Are you talking about wires that attach to voltage regulator bolt? Those are ground wires for the headlights.

Hank

70 Chevelle SS396(454), M20, 3.73
My Chevelle
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post #14 of 28 (permalink) Old Jun 29th, 10, 6:02 PM Thread Starter
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George
 
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Re: Gen light question

Quote:
Originally Posted by Finally View Post
Thanks. Are you talking about wires that attach to voltage regulator bolt? Those are ground wires for the headlights.
Yes those wires. I thought that was what they were going to. There were those two attached to that bolt, then on the other top bolt a small metal can that plugs in the back of the regulator. I reused that can, since the new regulator didn't come with another one.

My '71 Malibu:

355 9.7:1, Edelbrock Performer RPM heads and intake, Clay Smith hydraulic roller cam (280/294 .516 lift), Holley 650 DP, Pertronix ignition

TH350 Allstar 10" converter

12 bolt posi, 3.90 gears, MT ET Street DR 275/60/15

W/ 3.31's…...12.87@104
W/ 3.90's…...12.70@106
W/ 125 shot..11.85@112
Geo71 is offline  
post #15 of 28 (permalink) Old Jun 29th, 10, 6:09 PM
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Hank
 
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Re: Gen light question

That all sounds ok. Like I said check the voltage at higher rpm and the bulb. With 14v at the battery your alt is charging.

Hank

70 Chevelle SS396(454), M20, 3.73
My Chevelle
Finally is offline  
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