Changed alternator and battery. Now have problems

[ciGARRETTsRbad4u]

First of all, my car is a '90 240 with a '97 '98 twin cam if that makes a difference.
My alternator went bad so I switched it out along with the battery at the same time.
When I started my car, I noticed the battery light in the gauge cluster was on, which was not on before when the alt. was bad.
I believe the alternator to be good because the car will run with the battery disconected. When I rev it up a little, the battery light will flicker on and off.

Not sure if this is related, but when I started the car, I also noticed a kind of buzzing sound from under the dash which was caused by this plug under the driver side kick pannel. When I disconnect it, the sound stops.
(sorry for the sideways pic)



When I disconnect the alternator from here

the 'buzzing' sound and the battery light will turn off.


Any ideas? Any help would be greatly appreciated. Thanks

[Kriskouki]

Spray clean the plug at the Alternator........

[bo2o]

try another altenator?

[mifesto]

im not gonna pretent to know exact what that plug is, but buzzing noise is often from dirty/poor connection

[los_inc]

your car has poor grounds
make sure everything is grounded to the body
the battery, the alt & the motor all to the chassis
i've had the same issue
-los

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[Okinawandrifter87]

If you further isolate where the buzzing is originating let us know as it might help to give you more help in what direction to pursue. To me a "buzzing" sound leans towards a relay being toggled or something shorting out and arcing but that's unlikely because more than likely with an errant ground you'd have more problems that what you're having now. Good luck!