This may be an ignorant question as I've never owned a 4WD truck. When I am in 4WD with my Tacoma and try to make a tight circle or u-turn (on-dry pavement), the truck feels like someone's applied the brakes hard and it's literally impossible to make the tight circle turn - it jerks back and forth and the tires "drag". A toyota service manager told me that I shouldn't be driving the truck in 4WD on dry pavement (only in snow, off-road, or heavy rain ) or I'll ruin the 4WD. Have you heard such a thing and is it true .... and why? I've owned 4WD SUV's and never had the problem, but then they are not trucks.
I imagine you have gotten your answer by now... The Tacoma is a part time 4WD system where the front and rear differentails are locked together at the transfer case. Since turning requires the front tires to rotate more than the back, unless you are on a soft surface that allows the slippage, you will have binding. 4WD is NOT for dry pavement (otherwise all cars would have it). Your 4WD SUVs must have been AWD (All Wheel Drive) which is the term for FULL TIME 4WD. Those AWDs have a third differential that allows the front and rear drive shafts to rotate at different speeds. A true off road vehicle will have a differential lock-out if it is AWD, because AWDs don't divide the power equally like a part time 4WD does... and is needed for true off roading.
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