1998 Jimmy, Not shifiting into 4x4

Discussion in 'GM Powertrain' started by otis24, Dec 14, 2008.

  1. otis24

    otis24 Member

    I have a 1998 GMC Jimmy. It does not seem to want to shift into 4x4 (electronic shift). The problem seems intermitten. I just purchased the vehicle.When I shift to 4x4, the 4x4 lights flash, then it kicks back to 2 wheel drive.
    It is -6 out and the windchill is probably -30. Could the cold weather be affecting the shifting? Will it correct itself during warm weather?
  2. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Yes the cold could be affecting the shifting.
    A trick we used to use on GM trucks and Wranglers for snow running was to carry a long collapsable hose you could attach to the tail pipe and route to the engine compartment, this would keep the engine compartment warm enough so the carb didnt ice up (along with cloth across the grill), sometimes you had to aim the end of the hose at the axle actuator to warm it a little so it would shift.
    I've also seen guys use small propane torches to warm the actuator, I wouldnt recommend that method though because theres to many flamable fluids under the truck for me to feel safe with an open flame.
  3. cascott325

    cascott325 Epic Member 5+ Years 1000 Posts

    sorry to break conversation, but where the hell are you to be in temps @ -6 in mid december? its not even the coldest part of winter here... come to think of it, is it officially winter yet, or is it still fall?
  4. andz74

    andz74 Member

    chevy wont shift into 4 high

    i have a chevy that takes awhile to shift into 4high and it has to with a vacum
  5. otis24

    otis24 Member

    Located in Chamberlain South Dakota, right on the banks of the now frozen over Missouri River. Would the actuator on this vehicle be electronic or vacuum, or a combination of the two?
  6. unplugged

    unplugged Epic Member 5+ Years 1000 Posts

    I believe the earlier 1996 and earlier versions used a thermal actuator and later models went to an improved version that wasn't affected by temperatures. Other sources spec 92 - 98 for Suburbans. See service info at: justanswers.com

    I replaced my stock unit with a replacement from NAPA. I didn't see the need for the upgrade since I wasn't having temperature issues. The dealer wanted $300 for the upgrade installation and parts: new actuator and harness. The actuator from NAPA was $80 bucks.

    If you do have the thermal actuator you may want to consider going to the cable conversion from 4x4 posi-lok especially since you live in a colder climate.
  7. otis24

    otis24 Member

    Does this cable kit have different possitions for 2 Hi, 4 Hi, and 4 Lo? Do the 4x4 lights continue to light up or is this system completely unhooked?
  8. otis24

    otis24 Member

    A mechanic at work reached under the battery and shook the hell out of things. After that, it would shift into 4Hi, but not 4 Lo. I will pull the battery and tray out one evening and check all of the vacuum lines.

    The indicator lights don't always light up right away when I select a different setting. Could the problems be a switch issue or would they more likely be a vaccum/actuator issue?
  9. jim1958

    jim1958 Member

    1998 jimmy shifting

    Are you hearing noises like a bearing cage grinding, that sounds like it`s coming from the passenger front wheel? And I don`t believe there is any vac involved in your year, I think it`s all electric. If you start hearing a grinding noise along with not shifting right, you may be in for an expensive transfer case job. You`ll need your VIN # to find out what transfer case you`ll need, if this is it.
  10. otis24

    otis24 Member

    I had it in the shop the other day. The mechanic checked it for a vacuum leak and did not find one. After leaving the shop, it would shift into 4x4. Presumably because of being indoors where it is warmer(?). However, when shifting back to 2 wd, the shift was delayed and when it did shift, it shifted with a pretty rough "thunk".

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