All four doors locks will not lock or unlock with key remote or by using the master switch on the drivers' side door. It was this way when I bought it and they said that a fuse was blown. It was repaired, but, the dealer said that they never found a reason for the fuse to blow, but, there must be a short somewhere in the system. It has worked well since they last changed the fuse in November 2012, but now the doors won't lock again and I can't find which fuse goes to the door locks. Can you help me?