Citroen Xsara Picasso central locking fault

Hi Steve. You need a 12 volt test light. The screwdriver type. Remove the N/S/R door trim then either peel back the waterproof membrane or cut the glue with a razor blade (this will need to go back or be renewed to prevent water from leaking into car). Then unclip the wiring plug from the c/l motor. The test light crocadile clip will need to be earthed (lock striker plate or check strap bolt)and then, touch the tip of the test light into each of the plug terminals in turn and operate the c/locking. One of the pins should go live for a second or two when you lock the car and a different pin should go live when you unlock. If the testlight lights when locking and unlocking on two pins, then probably the motor is faulty. Hope this is of some help to you.