Has a roaring sound from transfer case ? is it possible for a front bearing ,where front drive shaft attaches?

The front drive shaft moves when the truck moves.. This is a "All wheel system" NOT a 4 Wheel Drive system.. Yes there is a clutch pack in the transfer case that is supposed to send the power to the wheels as needed. for traction. Make sure you keep all the U joints lubed and in good shape.. these are very expensive drive shafts. You really did not tell us the problem.. possibly the truck does not go ?. in which case it could be a bad transfer case or possibly a broke output shaft on the trans. except for the output shaft and rear housing these transmissions are the same as the 2 wheel drive models.post a comment and let us know what you find, By the way check to see if there is any fluid in the transfer case..

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Sounds like a wheel bearing or a bad CV shaft or u joint in the front end drive shafts, if it is 4 wheel drive. it also could be a break pad rubbing cause the caliper is stuck pressed in.

If it's 4 wheel drive, it could be a bearing in the differential or transfer case chain on its way out.

If it's 2 wheel drive then all it could be is either brakes or wheel bearing/hub assembly.

Possible the actuator on the front axle is bad! You need to see if the front drive shaft is rotating when the 4HI is engaged with out running yourselft over in the process.

There is one actuator on the axle and one on the transfer case, the one on the trnsfer case locks the drive shaft in ans out of 4HI and 4LO. The actuator on the frontaxle locsk the front drive shaft in.

Also, try the wires going to the front actuator, they seem to break very easy and short, also the front Actuator, check it.

1. Raise and support the truck on jackstands.
2. Drain the transfer case.
3. Disconnect the speedometer cable.
4. On models equipped with the NP208 transfer case, place the case in the 4H position.
5. Remove the skid plate and if necessary, the crossmember support.
6. If necessary, on trucks with automatic transmission, disconnect the strut rod.
7. Tag and unplug all electrical connections and hoses from the transfer case.
8. On models equipped with the NP208 transfer case, remove the parking brake cable guide from the pivot on the right frame rail.
9. Matchmark the driveshafts, disconnect them, and remove them.
10. Disconnect the shift lever rod.
11. Support the transfer case and remove the bolts attaching the transfer case to transmission adapter.
12. Move the transfer case to the rear until the input shaft clears the adapter and lower the transfer case from the truck.

Sounds as though you a have a problem with the switch itself, although it could be the encoder on the transfer case , me--- I would have it checked at a transmision shop where they have a computer to check it. Every time you unhook a wire on the truck , you should have the + cable off the battery, cause this puts another code into your main computer.

Keep us uopdated.

need to check wheel bearings

Sounds like a front wheel bearing. Pretty common. You have to replace the hub as an assembly. No servicable parts inside.

Does the noise change pitch when you weave the steering wheel back and forth. Possible front wheel bearing.

It possible that the drive shaft need to be turn 1/2 turn and re installed, or the balance weight is missing from the drive shaft.

first i would check the tires , are they cupped or chopped on the tread? run your hand over the tread and see if it feels rough and uneven. take the truck to a auto repair shop and have them jack both front and rear axles off the ground, put the truck in 2 wheel drive and run the speedometer to the speed you usually hear the roaring noise, if you don't hear the noise , put the truck in 4 wheel drive, turn off the traction assist if it has one and run it to the speed you would hear the noise. if you hear the roaring noise with tires off the ground, the problem is in the drivetrain, (engine, transmission, transfer case, u-joints, differentials or the front left or right cv halfshafts or u-joints). the older models (97 98) had the front two driveshafts from the differential turning all the time, they engaged in 4 wheel drive from the transfer case and a solenoid on the front differential. depending on the miles you have on this truck, the most likely areas i would look at would be the tires, u-joints/cv joints, and front and rear wheel bearings. thanks and good luck.