Will not go into 4 wheel drive

Which of these does your vehicle have ?

Transfer Case - NVG 233-NP1 (Two Speed Selectable)
Transfer Case - NVG 136-NP4(One Speed Automatic)

The New Venture Gear NV233 is an electronic shift transfer, with the following three modes of operation, Two-wheel drive high range, Four-wheel drive high range, Four-wheel drive low range. The gear reduction for low range is provided by a planetary gear set. The floor-mounted shifter has been eliminated. A switch, located on the upper right side of the instrument panel, is used to select the operating range. The indicator lamps on the switch show the current mode of operation. When the four-wheel drive has been selected, the four-wheel drive indicator lamp on the switch is designed to turn on when the front axle has engaged.


Automatic Transfer Case
The single speed automatic transfer case system shifts automatically from rear wheel drive to four wheel drive when the transfer case shift control module (TCSCM) senses the difference in rotation speed of the front propeller shaft and the rear propeller shaft . Two vehicle speed sensors, one located at the rear output shaft area of the transfer case, and the other, located at the front output shaft area of the transfer case, send front and rear propeller shaft rotation speed information to the TCSCM.
When the front and rear output shaft rotations remain the same, the TCSCM sends pulse width modulation signals to the encoder/motor to keep the transfer case in rear wheel drive. When the front and rear output shafts rotations are different, the shift control module sends pulse width modulation signals to the encoder/motor to engage the transfer case into four wheel drive.
The system will automatically transfer a percentage of torque to either the front or rear axles as required to stop all wheel slip. When the front and rear output shafts rotations return to the same speed rotation, the shift control module sends pulse width modulation signals to the encoder/motor to position the transfer case back into rear wheel drive.
When the transfer case is engaged into four wheel drive, a lamp indicator on the instrument cluster will light. The automatic transfer case system is completely automated, no transfer case control button switching system is required.

Do you know what diagnostic trouble code's are ?

DTC C0300 Rear Speed Sensor Malfunction
DTC C0305 Front Speed Sensor Malfunction
DTC C0308 Motor A/B Circuit Low
DTC C0309 Motor A/B Circuit High
DTC C0310 Motor A/B Circuit Open
DTC C0315 Motor Ground Circuit Open
DTC C0374 General System Malfunction
DTC C0376 Front/Rear Shaft Speed Mismatch
DTC C0550 ECU Malfunction
DTC C0611 VIN Information Error
DTC C0895 Device Voltage Malfunction

Not OBD2 engine code's .

Hi Carmelo:
The answer should be yes. even the drive shaft to the front will turn. The front drive will be engaged in the transfer case when in 4 wheel drive, but not when in 2 wheel drive.

Then you need to check the linkage underneath the floor where it connects to the transfer case, and make sure it isn't loose or mal-adjusted.

TRY NEUTRAL ON THE COLUMN THEN MOVE SHIFTER ON FLOOR IN 4WD.I THINK YOUR TRYING TO MOVE SHIFTER ON FLOOR WHILE ITS IN DRIVE.

it is most likely an automatic awd, 4 hi is full time 4 wheel drive, 4 lo is full time 4 wheel drive but at a very low gear ratio and should not exceed 25 mph or could cause damage. and DO NOT shift into 4 lo while vehicle is in motion. Auto is a 2 wheel drive but automatically engages into 4 wheel drive under heavy acceleration.

I was researching the recalls for the 2002 tundra and havent found any recall pertaining to the 4whl drive. Sometimes when people have their 4wheel drive locked in and drive on pavement for any length of time, whether it be just a couple of feet or a couple of miles, over time it creates a binding of the gears in your transfer case. Once the bind is so great, the engaging and disengaging starts malfunctioning and leads to bigger problems overall. I could be wrong about this being the problem that you have but I think its something to look into. It wouldnt hurt to put your vehicle up off all fours and release the bind if any by running through the gears while in 2 and rour wheel drive while all four tires can move freely and release. See if that works for you. Check your gear oil front , center and rear and use much caution when attempting this suggestion. Also refer to your owners manual troubleshooting section for other possibilities. Merry Christmas. By the way, the electrical switch should be covered in the troubleshooting section also.

Sounds like an issue with the IWE gear ( spring ) not engaging.

The IWE ( Integrated Wheel End ) is vacuum & spring operated. When the truck is running and in 2WD, vacuum is applied to the IWE, and holds the IWE gear out. Once vacuum is removed ( placed into 4H or 4L or turn off ) the vacuum is removed, and the spring pushes the IWE gear into place, locking the wheel to the front axle.

Could be a plugged vent line, you can start by removing the vacuum line from that side, and the vent line ( same vacuum line, just routes into the engine compartment, and is not connected to anything ) and see if the IWE will engage.
If the spring seems to move, but the wheel is not engaged, you would need to take it apart to confirm if the IWE spring or the gear itself ( worn down from part engagement ) is the issue.

This is a block diagram of the IWE system


There was a TSB on the IWE solenoid, where water could get into the system, and cause the IWE gear to be part engaged, causing the gears to be ground down ( you would have heard a grinding noise in 2WD ).
This is the TSB
http://my.voyager.net/~sscully/file_tsb06_08_15.pdf

sounds like either a fuse or the do u have locking hubs that need to be engaged also when using 4 wheel drive there is actually only 2 wheels turning usually passenger front and driver back sometimes u also have to drive backwards to engage and also disengage 4 wheel drive finally it may be a transfer case problem check drive shafts and u joints make sure they are engaged

Your automatic locking hubs are broken. Very common on ford trucks. The front hubs are geared with hard nylon gears, and are easily broken. If you replace your front hubs with "warn (name brand)" manual locking hubs, your issue will be resolved, and you won't have that issue again on your truck.

If you replace the hubs with manual locking hubs, you will have to stop, get out of the truck, and manually lock in your hubs every time you want to engage your 4 wheel drive. It beats getting stranded somewhere with no 4x4 at all; like you have now.

If you replace your hubs with the factory automatic locking hubs, the issue will return again in time.

Putting it in four wheel drive does not eliminate the transmission. Honestly, it sounds like the transmission is on it's way out. A 4l60e in one of cars was acting the same way. It required a rebuild.