2000 Ford Expedition Q&A
2000 Ford Expedition Question: CAN SOMBODY KNOWS WHAT IS CAUSING THIS PROLEMS?
It sounds like a bad electrical connection. If wiggling wiring harnesses or wires at the fuse box or any harness makes the engine run better or worse, or components work or fail to work there is definitely a wiring harness or electrical connection problem. Look closely at the harness and connectors for physical damage, shorted out or burned wires, damaged insulation, and rodent damage, (mice and rodents frequently chew on wiring insulation potentially causing serious damage). If the harnesses appear in tact I would start by disconnecting each electrical connector one at a time look for oxidized or corroded electrical pins in each connector, use electrical connector cleaner (available at Radio Shack, or any electronics store) make sure the pins are undamaged, apply dielectric grease (Permatex dielectric grease part # 22058 or similar product) to improve electrical conductivity). Do not disconnect any harnesses that are yellow or orange sheathing as these are air bag harnesses or hybrid related harnesses, and always disconnect harnesses with the engine off, keys out of the ignition to avoid inadvertently setting a Check Engine Light or perhaps causing a voltage surge in a circuit. A lot of electrical system problems are caused by a marginal battery or a marginal charging system ensure your battery and charging system are operating correctly. Lastly if you have a good volt/ohm meter a good test to ensure electrical circuits have good integrity (good power and ground) is called a "voltage drop test", it checks for high resistance in a circuit. Look on You tube search for "voltage drop test" there is a good instructional video. For a wiring diagram Autozone have some popular workshop manuals for free on line once you register (for free) on their website http://bit.ly/autozone_repair_info or there is a company that independent auto repair shops "buy" their information from that offer a very reasonable service to do it yourselvers. You can get a one week subscription or year subscription very cheap. The information is year make and model specific repair procedures, service bulletins, component locations, wiring diagrams ect.... great quality information same as the professionals have ,much better than generic workshop manuals from parts stores, much cheaper than the factory manual try http://bit.ly/mitchell_repair_manuals_online and get an online repair manual subscription. - patrick mannion
As an addendum - the GEM module figures into all the functions you mention - check to see if there is water intrusion on the GEM or even on the fuse box from a water leak. This can cause the kinds of things you mention as well. - DaveJHM
Check fuse, make sure the prongs in the fuse holder are making good contact. - keithsplace