How do you locate and change 2004 mercury mountaineer ABS sensor?

The ABS sensor on a 2004 Mercury Mountaineer with AWD is in the front wheel bearing hub assembly. To access this sensor you must remove the wheel and tire, then remove the brake caliper and rotor. The sensor is attached to the hub assembly by a small socket head cap screw. The end is plastic and the wire is routed allong the brake line and attached with various wire looms. Be carefull when removing the sensor. Often the plastic is brittle and will break, making the remaining part quite difficult to remove. Often an ABS light on is an indication of a failing wheel bearing. Basically, if this is the case, replace both bearings and both sensors. If one is failing, the other will go bad within the next few thousand miles. Diagnosing a bad sensor is a 50% chance on getting the right one.