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4 Wheel Drive/SUVs/1999 GMC Jimmy stuck in 4x4

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Expert: - 6/22/2005


Question
Our 1999 Gmc Jimmy is stuck in 4 wheel drive low and we can not get it back into 2 wheel drive.  It started at first by flasing on the 4 Low button on the dash when in 2 wheel.  When you would stop or put it in Nuetral it would lock in 4 Low.  Now today when we went to start it up it went into 4 Low and we can not get it to shift back in 2 wheel.  Any idea what would cause this.  Could it be the switch going out or in the front end.

Answer
Vicky,

I'm not familiar with the system used on the GMC, but  I would suspect a faulty switch, or vacuum line.  On some vehicles, this can be caused by a bad electrical ground, or broken wire leading to the transfer case.

I would suggest that you purchase a repair manual for your GMC.   A Chilton's or a Hayne's manual can be purchased at most auto parts stores for $20.  They have a lot of information on basic trouble shooting, and repairs, including diagrams of the vacuum lines, and electrical wiring.  They, also explain how to test for problems such as yours.  These manuals are designed for a year or range of years for specific vehicles, and are invaluable if you are planning on doing any repairs, or maintenance yourself.

If you don't wish to check this out yourself, try to find a reputable shop that is dedicated to working on 4-wheel drives, and see if they will troubleshoot your problem.  Most shops will take a look at the problem, and give you a free estimate.

Carl

4 Wheel Drive/SUVs

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Carl Brandt

Expertise

Will discuss suspensions, lifts, lockers along with tire suggestions. Trail ratings and possible requirements needed for specific type of trails. Safety equipment and what you should carry with you. Certified off-road instructor. I am not a mechanic, and 4-Wheeling is a hobby, so if I can't answer a technical question it is due to my mechanical knowledge being related to vehicles that I have owned, or have worked on. I do not have manuals on all vehicles.

Experience

40 plus years of 4 wheeling in a variety of vehicles. At the present time, my major off-road rig is a 94 Jeep Wrangler with a spring over and a 1 1/2" suspension lift. This gives me a total lift of 7" or so. I have lockers front and rear. I have removed the track bars, and sway bar for maximum articulation. I am running a stock 2.5 ltr 4 cylinder with a Jacobs ignition along with a cold air high flow filter. It has 4.56:1 gears with a Dodge NV4500 transmission along with a 3.8:1 Atlas II transfer case. This gives me a final ratio of 105:1 in low gear/low range. Other vehicles I own, are a 96 Ford F-250 with a 6" lift, posi rear end, 36" Hummer tires, 5 speed with a fuel injected 460 ci engine, an 87 Samurai with an 8" lift, Ford 9" rear end with a spool, Chevy Dana 44 front end with an electric locker, 5.88 gears, 16% reduction in high range and a 6.5:1 low range with 35" Baja Claws, and a stock 2003 Grand Cherokee Overland. Trails I have run are the Rubicon (10 times), Dusey Ershim, Fordyce Creek trail, McGrew trail, several trails in Moab, Utah along with local monthly runs.

Organizations
Lost Coast 4x4's Cal 4-Wheel Corva UFWDA Blue Ribbon Coalition

Education/Credentials
Certified off-road instructor - Certificates in engineering/electronics

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