00 1500 wiper motor electrical issue

hi last year i had ice on winshield wipres froze i worked it and i guess burned out

i had replaced motor wasn't i and then found groun problem but it had burned that motor too when i bypasse the little black ground wire and just ran it to frame of truck worked for a bit then burned out the motor i guess

i got a replacement truck for parts it works in that truck put in ym truck no goo as i figured it was the mf switch.. nope if i put my ground wire to the motor works but i don't don't wanna burn it out...

but is here a wiring diagram or test procedure to knoe where that black wire goes too... so i can cut it off at base an run new wire to it... and is there a test to know if any of these wires melted so i can repair it.. or would it be just the ground wire shorting things.... as i don't want to short out it again like to make sure that not electrical is fused shorting etc... motors not cheap.... ohm readings or whatever procedures be great please

here is you tube video i took yesterday
https://youtu.be/st0vZgQYEuI
getting 12 volts on the ground don't think that's right