1999 F250 S/D Door lock switches will lock the doors but will not unlock them??? I cannot believe that both switches went bad at the same time and do not have a wiring diagram to troubleshoot myself. Any ideas?

 

Per owners manual on 99, engine fuse box #26 (20 amp maxi fuse), "if equipped with Remote Keyless Entry-driver door unlock relay coil, all door unlock relay coil, all door lock relay coil, park lamp flash relay. If not equipped with Remote Keyless entry-Power door lock motors.

This seems confusing to me, but it makes me think there are 2 relays, one to lock and one to unlock. A bad relay could be causing the problem. Exactly where the relays are located is currently a mystery to me, as the few described in the manual do not list the door locks.

Followup:
per a wiring diag I have, from fuse #26, a black/white wire runs from fuse 26 (always hot) to both a)an all lock relay and b)an all unlock relay. It lists 2 wires leaving the unlock relay, a pnk/lt grn to the door switches and a pnk/org to the door lock actuators