New alt and now wint turn off with key. Wtf bad alt?

[82sbshortbed]

I installed new alt today with new plug. Runs and charges good but keeps running when I turn the key off. I checked the black wire on the plug with key off and no power. Key on it gets power. So I don't know why it didn't turn off when you turn off the key. I had to pull the plug on alt to kill the engine. Could the alt be bad? I'm outta ideas. I could use some help. Lol

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Connected

 

[MarineOne]

You're back-feeding from your alternator to the ignition. You can connect a diode in the sensing line to prevent it.

But being as it's a new alt I'd say something is wrong with voltage regulator itself.

 

[82sbshortbed]

Gonna look more tomorrow but I think you're probably right.

 

[82sbshortbed]

Well went and bought my core back fir 17 bucks to see if that was the problem. They didn't have another one in stock so ordered one for tomorrow. So put old one back on and same problem. So wired in a sidemarker light socket like the Old one the pi had in there. Always thought that was weird but low and behold that fixed it. Now shuts off with the key. Lol

They bench tested the new one and said was good. So put new one back on and works fine now. Hahaha would have never guessed that.

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[Bloodhound1981]

If you wire in the diode in place of the bulb, that will work as well. Right now that bulb is taking the place of the battery idiot light which is why it is working.

 

[Grit dog]

Nothing to add other than I learned something today, reading this.
Thanks!

 

[82sbshortbed]

If you wire in the diode in place of the bulb, that will work as well. Right now that bulb is taking the place of the battery idiot light which is why it is working.

I thought this same thing about the dash light.