caravelle/t4 central locking problem

1994 T4 Caravelle - central locking fitted on all doors - sliding door doesnt operate ... there appears to be 2 potential sensors for the door - a black push switch fitted in the door pillar and depressed by the door and a 3 pronged copper looking switch in the door depressed by the pillar - the pillar appears to have contacts to receive the 3 prongs. The electrical connector for this appears to be disconnected

Which(if any) is the central locking sensor ???
What is that 3 pronged affair ???

cheers
John
OK - a test meter shows the 3 pin arrangement is the power supply to the sliding door !!!
Now find that the locking bar doesnt connect to a motor nor does the power cable !!! Maybe there isnt a central locking motor !!!!!
Could someone indicate where it sits in the door and what it looks like ???