Does the power to the door lock actuator , go into the door in wires , or through brass contacts in the door jam.
The brass contacts can require cleaning.
Wires running between the body and door can break due to flexing, as the door opens and closes.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.