I have a 98 Jimmy/Blazer. Whatever, sometimes my 4wd push button will flash but it only goes into 2wd and 4wd low. How do i put it in 4wd high? I guess im not doing it right?

 

also what is a safe maximum speed for 4wd high? And if going up a steep grade hill should i use a lower gear or 4wd low

 

Not sure on all your questions, but 4LO should be used off road, where high amounts of torque is needed, ie towing, pulling steep incline or dragging something a short distance or for slow off road crawling, 40 mph would probably be max speed in 4LO. To shift into 4LO, you'll need your owners manual, many of these have different requirements to shift into 4LO. Some are full stop, shift into neutral and then push 4LO, this may not be yours though. I do know, 4LO cannot be done on the fly or on the move!

4HI is safe at all speeds, but should not be used on dry roads, all the wheels need to be allowed to slip and turn at different speeds, dry pavement will not allow this. Snow covered, muddy, and loose gravel roads, are ideal for this mode, not wet paved roads.