2001 GMC Jimmy 4 wheel drive

  • 2001 GMC JIMMY
  • 6 CYL
  • 4WD
  • 150,000 MILES
Will not shift into 4X 4 lite flashes for short time then goes back to 2 high push button shift.
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have the same problem?
Sunday, March 29th, 2015 AT 12:36 PM

1 Reply

Front axle on "T" Series models uses a 7 1/4" ring gear. The front axle has an electric 4WD engage/disengage feature which allows shifting in or out of 4WD while vehicle is moving (under most conditions). The 4WD feature is shifted by a vacuum actuation system.

The vacuum actuation system consists of a vacuum switch and vacuum actuator. Shift mechanism in transfer case triggers vacuum switch to apply engine vacuum to vacuum actuator after about a 3 second delay. The vacuum actuator, in turn, pulls on shift cable which pulls on shift fork in axle. This connects the right axle output shaft to the front axle differential. Torque is now available to front wheels.

Right side of axle assembly consists of a solid axle shaft which rides inside of a stationary axle housing. An outer axle shaft with CV joint is attached to each axle flange. Each axle shaft consists of a flexible shaft using a right tripod joint and outer CV joint. CV joint splined/threaded shaft on outer end of axle shaft slips through steering knuckle/hub assembly. See Figure. The differential uses a conventional ring and pinion gear set to transmit driving force of engine to the front wheels. Ring and pinion gear set transfers driving force at a 90-degree angle from front drive shaft to axle shafts/CV joints.
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Sunday, March 29th, 2015 AT 8:31 PM

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