2017 TRDOR transfer case not engaging

Flashing light on the dash. Yes the front engages. Have confirmed the front drive shaft spins when the truck moves.

 

That isn't confirming the ADD engages. Flashing light and driveshaft clues point to only the tcase engaging. ADD sounds like your issue.

 

I must have missed something. What is the ADD.

 

Automatic disconnecting differential or something like that. It’s the actuator at the front diff that engages and disengages it from the driveline. Both it and the t-case actuators have to engage for 4wd to function. If the driveshaft is spinning then it sounds like the t-case actuator is working and the ADD is not.

 

That part is working. I have heard it move.

 

We've explained why it's likely not working. You need to investigate more thoroughly. G'luck.