NONE of the door UNLOCK switches work but ALL SWITCHES will LOCK - 03 Town Car

[ArtBlanc]

All 4 door lock switches will lock but none of them will unlock.
I just replaced the DDM because the old one would make the locks constantly lock and unlock.
Could this replacement DDM be causing this new problem? It is a used part.

As a side note the trunk unlock button is no longer working either.

 

[Town]

Welcome to the Forum.

For the 2006 and up models the DDM needs to be programmed for the vehicle according to the service manual, and this has been found to be true by other members. The models up to 2002 seem to allow used DDM to work. So I am unsure whether a used DDM will work on your 2003 car. The locks are wired through the DDM so I will see what tests there are on the switches.

I presume the key fob provides remote unlocking of the doors and trunk, or do you use a key? If the remote access does not work then the DDM is probably the problem.

Good luck.

 

[ArtBlanc]

The key fob is not working either which I was expecting and the keyless entry code is different.
I used FORSCAN to read the keyless entry code but it isn't working when I type it on the keyless entry keypad. I'm not sure if the keypad is the problem. We were already having trouble with the keypad.
I'm trying to learn how to program the DDM with FORSCAN but haven't found much information so far

 

[ArtBlanc]

I can't program the fobs the normal way since the door unlock button doesn't work

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[Town]

I looked at the 2001 service manual and it appears that a new DDM requires programming by the Ford scan tool to install the old DDM program or a new program downloaded from the Ford system data base. So a working used DDM may work fine, but how do you know if your used DDM works correctly? I would have thought your supplier would include the DDM code with the DDM. I don't know anything about FORSCAN but I cannot imagine it being able to access the DDM code from the module itself (Ford scan tool can do that). If FORSCAN is any use at all it will be able to access the DDM module and extract the DTCs (Diagnostic Trouble Codes) to identify any problems. A new DDM has a DTC set that the Ford scanner eliminates before programming.

Attached is a pdf of the wiring diagram for a 2001 Town Car that is likely the same as your model's wiring diagram. The keypad can likely be tested by checking for power and ground and pressing a key and testing the related connection for voltage. Other than the remote fob and keypad access requiring the DDM code the door locks should work without you having the code. Have you tried programming the seats and exterior mirrors and adjustable pedals if equipped just to see if the DDM is responsive?

A new DDM and its programming by Ford will be expensive. Certain Locksmiths have the equipment and access to Ford systems to program your PATS and chipped keys so the DDM access and programming should be easy, so it may be an option.

Good luck