Did you solve the issue?
I had intermittant issue's with the tailgate since getting the truck and drove me and the dealership mad for over one year. Changed everything in the tailgate, stating with the bed step sensor, battery was also suspected and changed, etc. Lately they changed the complete tailgate module, still the same error.
In the display you could not change the mode of the tailgate (electronic / manual or vice versa), in the Forscan the module was not connected.
During my holidays I left the car at them, and they checked the complete wiring. Supposably you can monitor the modules and generate a sound when something happens (with the laptop). Turned out to be a faulty connector somewhere in the car, which opened and closed the CAN-BUS. Throwing out the error. The replaced the faulty pins and since then it is solved.