Alternator light blinks when release brake

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My alternator light turns on every time I release the brake (when the lights go off). It also blinks when my blinkers are active. However, if I turn on the headlights, the problem stops.
Does anyone have any idea where the problem might be?

I already installed a new voltage regulator but that didn't solve the issue.
As far as I know, all the components are stock, (voltage regulator is the motorcraft solid state version)

Battery reads 13.3 V when engine off and 14.6 when engine idling.
 
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1971 Mustang Mach 1 M code 351 4 speed
I will take a stab at this, but I suck at electronics. It seems that your are getting too much voltage and that is turning on the alternator light. When you turn on the headlights, the voltage drops and the alternator light goes out, same with the brake lights. This is usually a voltage regulator issue, but being that you just changed that, unless it is a defective unit I am at a loss. Your alternator may be starting to go or maybe you have issues with your battery. Check the acid level on the battery. You may just want to have your alternator and battery checked, it is probably one or the other or both, unless you got a defective regulator.
 
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My all time favorite vehicle is our 1969 Shelby GT500
Almost every time I see strange behavior like you are describing it turns out to be a poor ground somewhere in one or more areas. Look at Circuits 904 and 297 to see what they feed, and where their various components are grounded. Also, check to see if the Alternator light comes on when using the windshield wipers (I bet it does) - as that will further indicate a poor ground. I have attached two schematic snippets showing the circuitry for 904, 207, and also showing the letters for the Voltage Regulator connector (I, A, S, F). I hope all that helps. Chasing down poor ground connections is a thankless task, but those kinds of problems are always nice to finally nail down.
 

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Joined
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My all time favorite vehicle is our 1969 Shelby GT500
Thanks! As mrgmhale said, it turned out to be a ground issue.
In my case, the battery was grounded to the engine lacked the connection from the engine to the chassis. I got a grounding strap to the chassis and the problems are gone.
Woo Hoo! I am glad you nailed the ground problem. I bet you feel a lot better now. Thank you for following up re: the ground issue having been found and corrected.
 
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