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Discussion Starter · #1 ·
I just spent a couple hours trying to find answers here in the forum and still need help. The car is a 72 Malibu with alternator from an 85 Cutlass. All wiring to old external regulator was cut and the blue/brown wires connected to the alternator as per Tech Ref#14 here on TC. I went through entire harness(due to its age) and repaired connections and wires where needed. The system is grounded fine throughout the harness to body metal, frame and engine. I set up "remote sensing" to a junction block as per this website and the Mad Electrical website.
Hopefully that answers all the initial ?'s you may have about what has been done. The problem is that after the upgrade from the older style alternator to the 12SI model, the gen light stays dimly lit. This happens once the key is turned on and car running. Car charges fine and runs great with no issues. Headlights are nice and bright, no flickering. Any help is appreciated. I would like to know the issue before I just connect the brown wire directly to a voltmeter and bypass the gen light altogether.

thanks
 

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A bad diode in the diode trio, inside the alternator, will cause the light to glow dimly when running. Is the alternator new? Can you measure the voltage on the alternator output terminal?

"I would like to know the issue before I just connect the brown wire directly to a voltmeter and bypass the gen light altogether."

I would connect a volt meter to the IGN terminal of the fuse block. Leave the light connected as is. It is needed for initial excitation. Besides the brown wire would not give a useable voltage reading.
 

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Discussion Starter · #3 ·
I will take a look at that this weekend. Will autozone/checker be able to see the bad trio if that indeed is the issue? thx.
 

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Discussion Starter · #4 ·
I would like to thank Elree for coming out today and helping me out with this problem. Looks to be a problem in the harness itself from a previous hack job. thanks again Elree for the help.
 
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