Hi there welcome and thank you for the question hope i can be of some assistance to your problem
Has your boot light ever come on when you have opend the boot?
How many wires do you have at the light unit 2 or 3 and is it located in the boot or at the rear in the roof lining?
Yeah it has worked only just stopped in the last week and the light is in the roof lining just above the cargo area. I noticed because the door ajar light started flickering but all doors were shut then the ajar light stopped completely for the boot lid
can you tell me how many wires you have at the rear light unit and also how many wires you have at the tailgate latch and what colours they are as i am just trying to work out which system your vehicle as on it.
Also if you use the interior boot release button does the boot open?
3 wires in the light fitting red/yellow into single plug and black/yellow and black into an angled plug in the lock there is 4 wires black, white/green pinstripe, black/ red pinstripe, black/blue pinstripe all going into lock and yes the boot release button works seems to be mechanical (bit like a bike brake cable).
Ok then the swtich is located in the rear latch unit now the lights are linked to the swtiches directly what happens is the swtiches in the latches give an earth to the central locking module when operated and then the central locking module sends a feed to the central timer module and it is this that then earths the light units to swtich them on, now as the lights work on the other doors this tells us that the central timer modules and the wiring to the lights is all ok so you need to look at what the latch is doing.
The black / red wire is for the door ajar and is grounded when the boot is closed when the boot opens it goes open circiut so it knows the boot has been opened, you can check the operation of the swtich with a multimeter directly onto the latch just open a close it to see what it does then let me know.
I am thought it was probably the latch as the pins in the plug are pretty corroded it think moisture has got in somehow would that mean a new latch and plug as it looks like a sealed unit?
Yes if the latch is faulty then it is a new latch as it is sealed, if the pins are corroded then it would suggest that this is the likely cause of the fault.
Have you checked or replace your boot latch yet?