65 GMC voltage regulator

[finnishpetter]

Hi & thanks for accepting me as a member!

I have this problem with my external voltage regulator. I know that these issues were discussed on many other threads, but I could not solve my problem even after reading all the other posts.

Brand new battery, brand new alternator with brand new aftermarket external regulator. Using all factory connections and checked that the connectors are still wired as OEM.

When engine running the system will charge at about 13,8 volts and be just fine. When not running the battery will completely drain overnight. Went trough all normal procedures for searching the cause until noticed that pulling the voltage regulator connector stops the drainage. Checked again everything and replaced again the regulator. Same issue again. Made sure that the regulator is grounded with external ground wire. Still drains the battery.

Next step I noticed that the regulator has a bridge on post number 4 and put a pigtail on it. Measured at about 5 volts when all connected. Decided to test what happens if grounded - hallelujah - it stops draining the current from battery. Thought I´ve solved the mystery. Started the engine and checked charging - 12,5 volts - not charging. Pulled the pigtail ground on post number 4 and started charging immediately at 13,8 volts.

My question: what do i have to do to stop the drain and still get fully charging system??