Why is my passenger side sliding door making a loud grinding noise when locking?

poss door lock actuator is going bad

If the noise is occurring just at the last bit where the latch is pulling it in to close , then most likely it's a worn 'closer motor assembly' Rear latch and several other control cables built as one unit at rear of sliding door(power doors , right?) If it's a metallic screaching that goes along with most of the distance the door travels , then have the center roller checked- also common on those.