Electronic 4WD

Discussion in 'General Chevy & GM Tech Questions' started by grumpy old man, Feb 2, 2011.

  1. I have a '99 suburban 4WD and the question is can the truck be shifted into 4WD high on the fly? I did not get an owners manual when I bought it recently so have no information. I asked my local dealer and got the deer in the headlights look. The people I have asked with similar vehicles have given me different answers, so am looking for someone that knows for sure. Thanks in advance, the grump
  2. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    I assume you have push buttom and not the floor shifter 4wd. You can shift to 4wd high when going 25mph and slower. To go into 4wd Low you must stop, shift the transmission into neutral and then press the 4wd Low button and the shift the transmission in to 3rd gear. If you want to use the automatic 4wd it should be use on mud, snow or wet surfaces, just so theres some slippage.
  3. Thank you, I did finally figure out the 4WD low, not sure why but as stated it must be in neutral as it will not shift into low range in park, but I was not sure about the 4 high. That helps a lot because the only time I use it is when I am in the mountains and depending on whether the road gets sun or not you find yourself going from dry pavement to ice and it is a pain in the a.. to be stopping and starting all the time. You obviously have experience with the automatic 4WD, I have never tried it, does it respond quick enough to handle slow driving on the above mentioned road conditions? I will say that the antilock brakes work great stopping on an icy downhill. Thanks again
  4. strat804

    strat804 New Member

    Grump I'm gonna type you exactly what is says in my owners manual:

    Shifting to 4HI or auto 4wd

    Press and release the 4hi or auto 4wd switch. This can be done at any speed (except when shifting from 4lo), and the indicator light will flash while shifting. It will remain illuminated when the shift is completed.

    I don't have experience with it I only use 4x4 in snow when we rarely get it so I put it in when I start driving.
  5. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    Auto 4WD is not ALL WHEEL DRIVE, its just the computer and ABS sensors detecting slipping at one of the tires and turning the 4WD on when it needs to then it goes back to 2WD almost seemlessly and almost undetectable. You can too run 4HI on dry pavement, if you are driving in 4WD you are not gonna be going back and forth every 2 seconds when you hit a snw drift ad then pavemnent again. And you can also shift it into 4HI at any speed, my advice for 4LO, dont use it, it really isnt needed. Not in 99% of the encounters you will have.
  6. Thanks for all the information, my last encounter with 4WD was a jeep that was probably built before most of you had even been born. I acquired this thing because when we bought the mountain home the very first thing I did was to slide my wifes Lexus hybrid into a snow bank, and my mercedes roadster is definately out of the question. Depending on where you are in the community you can be on a well serviced road an occasionally serviced road a we will get to it when the 4th person calls to complain or a we do not even admit that the road exists. Being old my brain leaks and I will shift it into 4H and forget that it is there, I have driven many miles on dry pavement probably to the detriment of the drive train. Following the information given by vncj96 I will try the auto 4WD and see what happens. I suppose if I had thought about it logic would dictate that the same sensors and computer system that controls the anti-locks controls the auto 4WD, and the anti locks work better than the ones on the Lexus. I guess that I just have not reached the point that I trust electronics yet. Thanks again for all the information, the grump

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