How to troubleshoot remote door unlock problem. on 1995 Buick LeSabre

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Where to start to diagnose remote door unlock/open problem. Remote will not unlock right front or left rear door. They both quit working at the same time so don;t know if it;s a fuse, common wire, etc. Left front and right rear doors work fine.
(1) Answer
The first step would be to determine if the locks work correctly (lock and unlock) when using the door lock buttons on the front doors, also do the doors lock with the remote? If the doors will not lock or unlock from the door switches or the remotes then I would suspect the actuators in the offending doors are at fault. The door panels will need to be removed to test the lock and unlock signals to the actuators.