Your system is mechanical and electrical on both front doors. Your trunk pump is vacuum and pressure ... lock, unlock. You should have a 1 to 3 connector under the front passenger carpet. Apply vacuum and pressure to the driver's door line and see what happens. This should tell you if you have to pull the inner door panel. Also check the lines at the door/body flex point. I'd bet you have a bad driver's door lock. I had the same problem with a 83 380 SEL and both the lock and the pump were shot.