Have Ford Questions? Ask a Mechanic for Answers ASAP
Just so I completely understand your problem with the 1999 Expedition I need to ask a few questions.
Do the power door locks on any of the doors including the rear hatch work with the power door lock switches on the front door or the remote?Does the keyless entry key pad light up when you press any of the buttons?
Have you had any rain in your area lately?
The relay block in under the dash on the passenger side. There is a access panel on top of the dash to access them. But if the key pad did not light up when the locks did not work, it is not a relay issue. You may want to have the dash fuse box and the GEM module mounted on the back side of it check for moisture and or corrosion in the bulk wire connectors on the dash fuse box. This body style which is shared with the F150 that it is prone to a water leak on the drivers side which allows water to lightly drip on the dash fuse box and cause electrical issues.
Please keep me informed.