One problem related to ignition module has been reported for the 2003 Ford Expedition. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Ford Expedition based on all problems reported for the 2003 Expedition.
Outside mirror lights and interior lights would not go off after getting out of vehicle and pressing remote lock button. They eventually ran the battery down. This was after a hard rain. A few weeks later the same thing happened only this time, the radio would not turn off (key out of ignition and doors open) the chime kept going off and the battery went dead because I did not disconnect it. I researched online and found this is not uncommon because the windshield leaks, from the factory, and water drips down onto the computer module and fuse box. I checked my fuse box and I did have dripping water in it along with corroded connectors, inside the vehicle, indication long term intrusion of water. This causes all kinds of problems. Other owners have reported complete loss of power while driving. Upon inspecting my oem windshield I found it completely separated at the top and I could see light between the glass and seal. I now have to buy a new windshield along with fuse block and computer crap. The other problem is that the entire top of the windshield, as mentioned, is not sealed. I have been informed that the windshield integrity is a huge part of the strength of the vehicle and the windshield is used to support the passenger side air bag in case of deployment. I don't have that integrity on my vehicle. This is very unsafe condition and this should be something that Ford pays for.