Well all my locks have been functioning in tip top shape until very recently where I can only open the front doors with the key, the rear door locks won't open, on occasion the driver side rear door will unlock with the rest of the locks but then it won't lock. Same with the trunk, I can only lock the doors with the trunk, I can't use it to unlock. What's the problem? Also I am installing a keyless entry system very soon and I was wondering if this would cause any sort of problems with the installation? Thanks.