What causes rear wheels not to engage whether in 2 or 4 whhel drive? Front ones only turn when in 4x4.

I am not familiar with the model. I wonder does it have differential locks? If it does, that could be the trouble.

In order for an axle to lock there must be some fairly serious trouble with it - something broken inside.

It is impossible to drive a true 4 wheel drive vehicle on a hard surface because the front wheels (in a forward motion) always travel a greater distance than the rear wheels which results in wind-up between the axles.
When such things as crude old army vehicles had to take to the road they would be forced to stop periodically and one wheel would have to be jacked off the ground to relieve the wind-up before they could continue.

Regular road-going 4x4s have a unidirectional clutch fitted in the front drive to allow the front wheels to overrun the rears without wind-up. When diff-locks are engaged a road-going 4x4 becomes a true 4x4 and axle wind-up becomes likely.

From your description I speculate it did not get out of 4-wheel high but instead engaged the diff-locks and it became a true 4x4 and you experienced axle wind-up, something travelling in reverse will relieve.
I further speculate the fault has since corrected itself. It remains to be seen whether it was a one-off glitch...

did you turn the locks on the wheels, or check the fuses

If you have four wheel drive, turning the wheels sharply at a slow speed when in 4X4 mode can result in a wheel binding. The other possibilities are low lubricant in the rear differential, wrong lubricant in the rear differential if it has been replaced, or a bad differential.

Check the oil in the transfer case. If it has lots of metal in it... time for a new one. They aren't the world's strongest.
Another check: Lift the front of the truck, while keeping the rear wheels on the ground. Engage the 4x4 switch (then turn the truck off) crawl under and try to turn the front driveshaft by hand. If it turns and the wheels turn, the transfer case is the problem if it turns but the front wheels don't... front diff issues. Any grinding, crunching etc is also a clue.

On these issue, there are few solved help links for troubleshooting the issue easily.-------

Click the link below: ---

No 4x4 light on dash?

http://repairhelpcenter.blogspot.com/2011/12/no-4x4-light-on-dash.html

-----------

4X4 Truck makes roaring noise in the front end?

http://schematicsdiagram.blogspot.com/2012/01/4x4-truck-makes-roaring-noise-in-front.html

-------------

Car will not go into 4WD high or 4WD low?

http://schematicsdiagram.blogspot.com/2011/12/car-will-not-go-into-4wd-high-or-4wd.html

--------------

No 4x4 light on dash?

http://repairhelpcenter.blogspot.com/2011/12/no-4x4-light-on-dash.html

------------

4 wheel drive system will not disengage?

http://technoanswers.blogspot.com/2012/01/4-wheel-drive-system-will-not-disengage.html

----------

4WD light is flashing and beeping? NO 4WD high?

http://schematicsdiagram.blogspot.in/2012/02/4wd-light-is-flashing-and-beeping-no.html

----------

2002 Jeep Wrangler: 4WD Idiot Light is ON?

http://technoanswers.blogspot.in/2012/06/2002-jeep-wrangler-4wd-idiot-light-is.html

----------

Traction control switch will not engage on 4WD High or Low

http://whoisbyme.blogspot.com/2012/10/traction-control-switch-will-not-engage.html

-----------

4WD light flashing and 4WD will engage after few minutes

http://repairhelpcenter.blogspot.com/2012/10/4wd-light-flashing-and-4wd-will-engage.html

------------

2008 Toyota Tundra: 4x4 Wheel Drive Light is Flashing?

http://technoanswers.blogspot.in/2012/05/2008-toyota-tundra-4x4-wheel-drive.html

----------

4x4 front differential will not engage the axle on ford?

http://technoanswers.blogspot.in/2012/02/4x4-front-differential-will-not-engage.html

-------

4x4 will not engage on Ford F150?

http://technoanswers.blogspot.in/2012/02/4x4-will-not-engage-on-ford-f150.html

-------------

Dodge Ram 4x4 light keeps flashing

4X4 LOW LIGHT IS FLASHING ON DASH

http://technoanswers.blogspot.in/2012/09/dodge-ram-4x4-light-keeps-flashing.html

----------

Ford 4x4 front wheels will not engage?

http://technoanswers.blogspot.in/2012/02/ford-4x4-front-wheels-will-not-engage.html

-------------

These details will help.

Thanks.

this is a rear wheel drive vehicle and as such the rear wheels are always engaged.when in 4 wheel drive the transfer case in gages and the front differential connects and is engaged.unless the 4 wheel drive is engaged the transfer case just free wheels.

If I read this correctly ( which I might not have, bit early for me ), the front drive shaft will engage ( from the transfer case ) but the front wheels are not engaged ?

If so, sounds like either the vacuum from the IWE ( Integrated Wheel End ) is not being released, or the IWEs have had an issue with part vacuum ( damage vacuum lines ) and the IWE gear is rounded off.

If you pull the vacuum lines at the IWEs ( there are 2 lines, 1 is the vacuum line, the other is the vent tube that routes up into the engine compartment and is not attached to anything ), the front wheel should engage ( might need a 5 * turn to mesh the gears ). With the vacuum lines off, jack up the front axle ( take precautions, chock the rear wheels, parking brake, jack stands, etc ) see if the front wheels are engaged ( turning one wheel should turn the other ). The option is to do this after the truck has sat over night, and the vacuum has been released out of the vacuum reservoir.

If the wheels turn correctly ( engaged ) I would think the contact plates in the transfer case are not making contact. Good starting point for this is the connector on the side of the transfer case, some times this gets gummed up, and the pins do not make good contact. The contact plates in the transfer case are used for a few things, one of them is to signal the IWE solenoids to release vacuum to the IWEs.

Operationally vacuum holds the IWE ( Integrated Wheel Ends ) out, and once vacuum is removed the spring engages the IWE.

Here is a black diagram of the IWE vacuum system

Drive Axle Joints or Wheel Bearings?

If you have a CJ or Cherokee, when you move the 4x4 lever, it engages the transfer case which then transmits power to the front as well as the rear wheels. For most (99%) of all four wheel use, you use the front position on the shifter one notch behind the two wheel drive setting. Use 4 low only for pulling vehicles out of mud etc and don't drive in that range. If it sticks in 4wd after disengaging it, usually backing up about twenty feet will help.
If you have a Grand Cherokee, the 4x4 usually is a quadratrack unit. That one stays engaged but only goes into 4wd mode when the rear wheels begin to slip. (by itself). Rules for using low are the same.
It is very important to run the exact same size and style tires on any 4x4. It is mandatory on quadratrack units. Use of odd sized tires can cause driveline damage.
There are variations on different year vehicles but the basics remain the same.

my computer problem is hard disk system found warantty hard disk