47RE lock/unlock...
 

Hey guys! So, a few months ago I started getting the infamous tranny lock/unlock from 4th TC lockup back to 3rd then 4th again... I added another ground to the alternator to the passenger battery to the fender and it worked like a charm for a while then it started again... I had the alternator tested and the diodes are fine after the test... So, I was wondering if anyone had another solution? Thanks!

Yep, take a look at your alternator brushes! If they are worn and are arcing you get the dreaded noise.

Then take a look at the cable ends at the batteries and in the power distribution center, sometimes they corrode and have high resistance.
In some cases there is also a bit of corrosion on the fuses and their terminals, cleaning there does also help with light output.

HTH

Thanks for the reply! I got the alternator tested at an auto electrical shop... Everything came back good, diodes are all good and all that.. I did the foil wire wrap and that worked for maybe a day