Four wheel drive low will not lock in

2007 GMC SIERRA
143,000 MILES • 5.3L • V8 • 4WD • AUTOMATIC
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BTOLER
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When i turn the four wheel drive knob out of four wheel drive high or low, it kicks out hard; good jolt. Is this typical? Thanks
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Apr 19, 2018 at 4:01 PM
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STRAILER
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You need to be stopped to change range gears. Do you feel a jolt when it is stopped? Please let me know.

Cheers, Ken
Apr 22, 2018 at 11:14 AM
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BTOLER
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Yes sir, both the high and low 4AWD coming out of 4WD a jolt.
Apr 22, 2018 at 12:28 PM
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STEVE W.
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I run into this now and then if the front axle is not disengaging properly.
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Apr 22, 2018 at 6:09 PM
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STRAILER
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Nice, that sounds like it to me as well. Please let us know if this fixes it.
Apr 23, 2018 at 12:33 PM
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STEVE W.
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Check to be sure the front actuator is actually operating properly. As they wear they do not pull the release collar fully. Then as the vehicle moves you get some torque wrap in the drive line and "bang" as it finally releases. The other issue can be that the splines get twisted if someone tried to engage or disengage the four wheel drive when the tires are spinning. Both will cause the front interlock to bind.
Apr 23, 2018 at 12:56 PM