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1996 GMC Jimmy 4WD


I have a 1996 GMC Jimmy and I have just tried to use the 4WD for the first time. I’m about to take it to the shop but since it snowed at least 15 inches I need the 4WD to get out of my parking spot. The rear wheels engage but the front ones do not. Is this just the vacuum hose being faulty and is there some easy way I can test this without having to remove the battery and battery tray?


My 84 S-15 the 4wd was vacuum activated. Not sure about your vehicle though. Most vehicles these days are electronically activated

Yes, mine is vacuum actuated. Guess that part went out. Can’t get it out to get it into the shop since it’s too snowy/icy.

A major drawback of the automatic shift-on-the-fly 4wd (as opposed to the kind where you have to get out and flip the hubs over) is that you need to be moving to engage the 4wd, so if you’re stuck somewhere in 2wd, there’s no way you can get the 4wd engaged.

Give your owner’s manual a read to find the specifics of your particular system, but I believe you’ll find this is the case.