During diagnosis or repairs of the transfer case (RPO NQF) on some 2019-2023 Silverado MD 4500/5500/6500 models equipped with four-wheel drive, the transfer case learn procedure may not be completed if the transfer case actuator is not installed correctly. Movement of the actuator to the alignment bolts during service may lead to the transfer case binding in addition to the learn procedure not being completed.
When installing the transfer case actuator, the actuator keyway spline must be in the proper location. (Fig. 5)
Fig. 5
When aligned correctly, the keyway spline on the internal shift shaft and the transfer case actuator will be approximately in the 10 o’clock position. (Fig. 6) The actuator should slide fully into position without any need to move the actuator to align the bolt holes. The actuator should only be removed or installed with the transfer case in the 2HI position.
Fig. 6
If the alignment spline is not in the 10 o’clock position, the bolt holes will not align the actuator to the transfer case.
If the actuator is in the proper position and the transfer case shaft is not, the shift shaft can be moved using a suitable tool to adjust it to the 10 o’clock position.
TIP: If the alignment spline on the transfer case is not located in the 10 o’clock position, do not attempt to move the actuator using the scan tool. Instead, using a fused jumper wire on the bi-directional transfer case actuator circuits and a suitable power supply or battery, jump the control circuits of the actuator motor to move the spline into the correct location. Over movement of the actuator motor may cause damage to the internal sensor, so care should be taken to not allow more than 360 degrees of rotation in either direction.
Do not twist or move the actuator to line up the bolt holes. Moving the actuator may cause the internal gears of the transfer case to bind as well as prevent the learn procedure from completing.
If the learn procedure fails once the transfer case actuator has been installed correctly, reattempt the learn procedure with the wheels off the ground to alleviate any internal binding of the transfer case gears. If the learn procedure will still not complete, in a safe location, attempt to gently rock the vehicle to help align the internal components to allow the shift to complete. If the learn will still not complete, replace the transfer case actuator. Refer to the appropriate Service Information for transfer case actuator installation.
For additional information, refer to #PIP5894.
– Thanks to Bill Alley
