2004 buick rainier front axle will not engage

If it will not disengage the transfer case out of 4wd drive then pull it and have it checked out . Understand that if you drive in 4WD on hard surfaces then there is drive line torque wind up that occurs as the front and rear wheels cannot even out the differences in travelled distance because there is no mechanism to allow this to happen . Consequently any shifting mechanism like levers -actuators - motors will not shift as the teeth load prevents it from happening..4w is for off road and snow and ice conditions where the wheels can slip and equal out the wind up. Any way driving in 4wd on hard surfaces dramatically increases fuel consumption from the torque wind up situation.

All wheel drive is just that-- All wheel drive-- not to be confused with 4 wheel drive . The difference is with AWD there is a 3rd diff in the transmission that allows the front and rear wheels to operate at different road speeds . When 4wd is selected that 3rd diff is locked and so both front and rear wheels drive at the same speed regardless of ups and downs in the road surface . This results in a torque wind up in the drive train and places load on "U" joints --splines --CV joints and gear teeth . The grinding on turning corners will be the CV joints trying not to flex because of the torque wind up . How to prevent this problem=== Do not use 4wd on hard road surfaces === as the tyres cannot slip to relieve the torque Restrict the 4wd use to snow , mud and loose surfaces TO fix the problem unselect 4wd drive and reverse several yards to release the pressure in the drive train and the actuator has a chance to pull the gear out of lock up. If that doesn't work check that the actuator is actually working

there is an actuator in the front axle that engages the drive shaft to the wheels. there is also a vacuum actuator i believe in that model it is under the battery plate. if you put on lift you can trace the cable from the front axle back to the actuator and check the cable, actuator and vacuum lines. Gm's system is complex and when is messes up its a night mare. but common failures are actuator cracked or broken vacuum line.

your wheel cylinder for the brakes could be leaking or faulty. id check that out

Best and cheapest to fix is to replace vacuum lockers with manual lockers. It is easy to do. Only 6 bolts per front wheel. This is the most trusted way of 100% engagement.

Check your front wheel bearing and hubs when they defect the sounds increase on turns from one side to the other, due to the weight(load) displacement loaded on the bearings.
If your vehicle has front wheel drive this also can be the beginning of a defective front axle/axles C.V. joint(constant vellocity joint).

my computer problem is hard disk system found warantty hard disk

LOOK FOR A FILLER PLUG ON THE FRONT AXLE ON DIFFERENTIAL HOUSING.AND THE REAR AXLE HOUSING ALSO HAS A FILLER PLUG.

I have the same car. Mine is automatic. What is yours?

Possible scenarios:

1/ Is the FWD on the dash panel lit up? This will tell you that only the front wheels are engaged without power to the rear wheels. The manual tells you if you have a flat tire in your car, you have to make it into a FWD by inserting a fuse in your fuse box. Check and see if the circuitry isn't shorting out your awd which is making it fwd.

2/ Because the car has open diffs in the front and rear axles, you (or your friend) might see only the front wheels spinning and not the rear wheels. The power is transfered to the wheel with lowest resistance. With the front wheel spinning, one of the rear wheel(s) should also spin. Might not be a solution but maybe you can't see the rear spinning wheel because it's spinning on the other side.