I am having a similar issue on a vehicle I have purchased. The car locks and is secure but when driving the car is constantly telling me the boot is open, plus when stationary and locked I do not have the reassuring red flashing light on the inside of the drivers door to help determine thieves!
Have looked for any debris in the lock and have lubricated everything but the fault remains. By the look of the rear lock mechanism it looks like once you unbolt it from the body on the car there is little you can get at inside it.
Has anyone had a similar issue? Is the only solution or likely to be the purchase of a new lock unit?
Thanks folks
Paul