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Engagement Of 4 X 4 Drive

Discussion in 'Chevy Trucks' started by Ironmajor, Mar 12, 2003.

  1. Ironmajor

    Ironmajor Junior Member
    Messages: 1

    I have a 1997 Chev Siverado 1/2T 4x4 PU truck with Z-71 towing package.

    To engage the 4x4 hi or 4x4 low, one puts the vehicle's transmission into neutral, then press either the 4x4 hi or 4x4 low button on dash to engage. When I do this to engage either 4x4 hi or 4x4 low, the light continues to blink and the 4x4 (low or hi) does not engage.

    Does anyone have any idea as to what I am doing wrong?
    Thanks -
  2. plowking35

    plowking35 2000 Club Member
    from SE CT
    Messages: 2,923

    I believe you have one of two problems, either the actuator to move the transfere case lever is defective, or the front axel disconnect is bad. You will have to have a shop troubleshoot those two areas.
    With the push botton operated 4wd systems, the switch on the dash just operates a motor that moves the lever that normally would stick up through the floor of the truck, at the same time another motor slides a sleeve on the front axel to engage the power supply to the axel shafts, if either of these motors are to fail, you will not engage 4wd.
  3. nben

    nben Senior Member
    Messages: 101

    Is the truck new to you? The light on the button will blink until the front differential actuator is fully engaged. This may take as long as 20-30 seconds. Also, you may have to move the truck a little to line things up in the front end. FYI, you don't have to put the truck in neutral to engage four wheel high. It is designed to be able to be engaged on the fly. The front differential actuators are problematic on these trucks. If you continue to have problems, let us know and one of us will walk you through the diagnosis.:D

    Oh, and welcome to plowsite
  4. sonjaab

    sonjaab PlowSite.com Addict
    Messages: 1,425

    IRON ...The guys here are correct. You must put it
    in neutral and push button to shift into 4 LO only.
    4 HI you can shift on the fly ! If the light is blinking
    and NO 4 wd maybe its the front accuator (spl).
    If you have a test light you can unplug and check
    for power there.
    That part is only 60 bucks....Had one fail on my 97
    under warranty tho !................geo

    BTW: My 01 I don't have to put in neutral to shift
    to 4 lo. Just stop and push button........
    Last edited: Mar 12, 2003
  5. tuna

    tuna Senior Member
    Messages: 488

    The accuators are a common problem on GM IFS trucks.The way it works is the accuator is a small cylinder filled with a gas that when you shift into 4x4 power goes to the cylinder and a small heating element heats up the gas untill it expands driving out a small piston that engages the front axle.It was a poor design that often failed when packed with snow or sometimes took a long time to engage.Sometime in the late 90s they switched to an all electric accuator that is much more reliable.I had one fail on my old 92 Z-71 in the middle of a storm while plowing.I unppugged the power wire ,removed the accuator,taped 2 old lug nuts to the end of the piston,reinstalled it and it worked fine.I left it that way for the rest of the winter and even drove to Florida and back before I put a new one in .
  6. tovoninc

    tovoninc Senior Member
    Messages: 105

    I did a similar jury rig on my 88 3/4 ton front axle.

    You can also buy an after market cable actuated front axle device. Cost ~ $170 but you never have to wonder if the axle will engage or not!

    not sure, but it may be possible that by not moving while trying to engage the 4x4 hi it will never engage if there is any misalignment. some movement may allow the meshing of the drive train.

    my $0.02