I have a 2005 mercury mountaineer and my dash is saying check advtrec,awd disabled ,see owers manual

SOURCE: NO manual for a 97 mercury mountaineer

here is the fuse diagram

SOURCE: 2003 Mercury Mountaineer no heat

no you have to remove the vent between the hood and the windsheild its on the out side of the car it sounds like your freshair vent is stuck open

SOURCE: 2002 merc mountaineer awd wont come out of awd

If the vehicle is made to be a AWD you cannot get it out of AWD unless you take off the front drive shaft

SOURCE: In 97 mercury mountaineer, how to turn off "check engine" light

Go to the local parts store, have them check the codes (they will do this for free usually). It will tell you what sensor needs to be checked/replaced. Once the part is replaced, it will clear on its own. They can also reset the code, but it will come back if the trouble persists.

SOURCE: 2005 Mercury Mountaineer rear end whine, how hard to fix

Before you do this you might want to try fresh gear lube. On Ford products they use a synthetic additive in the rear and not in the front 4x4 axle.
The next thing would be to determine if it is a wheel bearing or a pinion bearing. You have to pull the axles and eliminate them as the problem. You might get lucky and not need to do the pinion.
The technical part of shimming the pinion gears with replacing the pinion bearing is about the worst part of the job. You won't know about the gears until you see them. You will need extra shims on hand.
It is a moderate job for two people. If you have all the parts it can be done in a day.

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