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Welcome to the FFO!

So the following unlocks all doors and does not lock them.
Key fob
Exterior keypad
Interior door lock switch

Correct?

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I have looked at a number of door lock wiring diagrams. Just have not found one for 2007 Expedition. However they all look similar with relays in a Smart Junction box. There are lock relays and unlock relays. And if I remember correctly the Smart Junction box is like a fuse box. Likely listed in the owner's manual.

I think what is happening is there is a relay or a ground that is not connected.
The circuit works with two relays. The power passes through one relay to the lock motor than then back to a second relay to ground. The power goes in one direction to lock and the other to unlock.

Both relays are needed to do both functions. The relays work in one direction but not the other because part of the circuit is not connected. Likely the ground side because you have a circuit in one direction.

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I think the switch is OK. A relay or a ground.

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Not sure.
The box has to be grounded based on the diagram.

Getting the actual diagram would be more accurate. For under $10 you get this manual. It will give you the exact wiring. Locations for all connectors, grounds, parts and systems. In addition it will give you wire colors circuit numbers and is really an awesome thing to have for electrical issues. Far too many people plunge blindly into electrical and with little cost can have the exact road map
https://www.ebay.com/itm/OEM-Ford-W...gator-Repair-Service-Manual/353110889856?hash=item52370c9580:g:4HUAAOSwcble6vYH

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Non-serviceable means non-repairable, Replace only.

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Do you think all the relays are in that block?

Not even close. There are relays in many places in newer vehicles.

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According to the book, that is the "accessory delay relay". I still can't find out what that does. But it does not appear to be the door lock relay.

The accessory delay relay's function is to delay operation of certain circuits (mostly accessories) upon initial engine start up. The delay may be just a few seconds and it allows all power from battery to be used to operate the starter motor upon initial engine cranking. It may also disconnect many electrical features of the vehicle with the key in the off position. Again to reduce electrical drain on the battery when the engine is not running. If you left an interior light on that interior light circuit may be turned off by this relay after some minutes. It is protection against unwanted battery drains when the engine is off and for a few seconds after engine starting.

Not he issue you are having and is the function of the accessory delay relay

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