The computer that controls the rear wiper is the
which is fitted behind the fuse box on the drivers side of the dash board. But the laguna 2 sports tourer suffered a water leak in the boot door. The drain pipe for the rear window detaches allowing water in to the eletronics in the boot door causing many different faults by corroding the wiring loom and the electronics (boot opening button, boot latch and rear wiper ect). My advice would be to remove the boot door inner trim and check the connections, if the connections look dirty or blue or if the sound proofing material is damp this more than likely is the fault. To replace the
would be expensive, it would have to be done by main dealer as it has to be programed and then the keys have to be programed. I have never needed to put a
on for this kind of fault before. Not saying that it is not the fault Renaults have a habbit of doing weird and wonderful things like this.