I have had this suzuki alto 55 reg 1.1L GL for almost a year now.
When I bought it the central locking on the passengers side was not working.
I bought a second hand motor/solenoid to replace it. When replacing, I tested the old one and it was completely dead.
This one worked alright for quite a few months the started to randomly work / not work when it wanted.
Rather than having it randomly work, I just disconnected it as I would like to know that my car is locked with out checking it.
Now I am trying to find out the cause to make sure it doesn't happen again.
It seems to only happen to the front passenger door and the other 3 doors are fine.
I have just tested it with a volt meter and the voltages are random between 5V - 9V.
Also testing it recently. when connected from cold, it always works. then the more times it is used in one go it gets weaker until I disconnect it and leave it for 5-10 minutes. then try again and works fine again with the same thing happing.
Inside the door it is a bit damp and also the rubber protection for the wires in between the doors is damaged but the wires seem to be fine.
If anybody has any thoughts on this that could help I would be very grateful. links below for some images I took of the door if any help.