4WD Inoperative with no DTCs Set

If no power is transmitted to the front axle in 4WD on some 2015-2017 Silverado 4WD and Sierra 4WD models (RPOs NQF, NGQ), the transfer case front output shaft drive sprocket body ring may be separated. The transfer case must be in the 4WD mode with the 4WD indicator light on in the transfer case select knob (NQF) or on the instrument cluster (NQG).

 

Shift the transfer case to 4WD and ensure that the 4WD indicator is on, which shows that all operations to achieve 4WD were completed successfully. This means that the front axle actuator is locked in the 4WD position. If there is no transfer of power, a mechanical link may be broken in the transfer case or front axle assembly.

 

If the front propeller shaft can be rotated independently of the rear, the disconnect may be in the transfer case. Check that the body ring that the synchronizer engages has not separated from the transfer case front output shaft drive sprocket. (Fig. 12) The ring is a press fit and should not separate from the gear. If it is separated, replace the transfer case front output drive shaft sprocket as needed.

 

Fig. 12

 

If the front propeller shaft cannot be rotated independently of the rear, the disconnect may be in the front axle assembly.

 

– Thanks to Steve Schipansky

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