Sportrak central locking, works but doesn't work!?

Forum: 

From locking the drivers door I can hear the central locking work (Can hear a couple of clicks, one when turning the key, and one a second after) But the passengers door doesn't lock.

There is no reading on a multimeter from the passengers side when locking the drivers side door.

Could it just be a relay problem?

Any help appreciated before I have another look tomorrow.

Cheers.

WD40 first method.

First try a few drops/squirt of WD40 down the door plunger. Manual pull/push the plunger a couple of times to spread the WD40. Dust often stops them workings.