when checking out to buy this vehicle I noticed that in low 4 wheel ,being on pavement just to check out engagement. I gave it gas it started to move and then it was like it jumped when engaging. I then put it in high 4 wheel and it moved foward without jumping. The 4 wheel light was on both times.
You shouldn’t be in 4 wheel drive low or high on dry pavement.
The vehicle has a transfer case and not a center differential for the drive system. So on dry pavement the transfer case is trying to distrbute the torque evenly to the 4 wheels. Transfer cases aren’t designed to do this. This only works if the vehicle has a center differential. Such as on an all-wheel drive vehicle.
What year is the Toyota 4Runner you are checking out?
Some years have what is called selectable 4 wheel drive. The 2003 V-6 we own has this feature. In 4 wheel drive high it is the same as an all wheel drive. However, a button can be pressed to lock the differentials so that all wheels will turn at the same time. This is only when the vehicle is stuck. If you select 4 wheel drive low, the gearing is really low. Again, the button can be pressed to lock the differentials. There is also a 2 wheel drive position. According to my owner’s manual, the vehicle can be driven in 4 wheel drive high all the time, but it will cut into the gasoline mileage. The V-8 4Runner in 2003 had all wheel drive.
However, earlier 4Runners had part time 4 wheel drive and 4 wheel drive isn’t suitable for highway driving. I think the more recent 4Runners have just part time 4 wheel drive.
With the selectable 4 wheel drive that I have, one can switch from 2 wheel drive to 4 wheel drive high while the vehicle is moving. However, 4 wheel drive low should only be engaged when the vehicle is stopped and is in neutral. If the vehicle you are checking out has the selectable 4 wheel drive, it is performing as it should. There is a knob on the dashboard marked 2 wheel drive, 4 wheel drive hi and 4 wheel drive low.