Hi all,
my X300 suddenly won't central-lock using key in door. If I remove battery lead for a while and reset system, it works for about an hour, then stops working again. I thought it might be my battery being old. It is 6-7 years, a 780CCA battery. I had it load-tested today - it reads 13v at terminals with car switched off, and loaded to 800CCA, so seems OK.

I never use the remote, but I have dug it out, will put fresh batteries in it and try again.
Any thoughts? - thanks in advance.

PS: here is a photo of my wheels - summer here in NZ, so cleaned both cars, and painted old-stool tyre black paint on all 8 tyres.

 

 

95 or 97 ?

You should have an early X300 series security lock control module that has all the external relays

The door lock position switch although not dependent on the relays can be tested from the SLCM located in the trunk fwd of the car's left trunk hinge

Do you have the version with 2 door Key barrels, one on each front door ?

Some Australian X300s have 2 key barrels

The wiring connections at the SLCM are a little different between the 1 key barrel

 

i had similar issues at one point and was unable to lock or unlock at one point, turned out the drivers door microswitch was dirty and not making good contact.
sprayed a few loads of carby cleaner and then circuit cleaner in there as it looked like a pain to actually remove it and that did the trick. freed up the switch and got it making better contact.