I apologize if someone else on this topic has already commented about a solution. I believe my friend and I have found the problem due to trial and error after we loaded a snowblower onto my truck and could not lower the tailgate. We believe the problem lies within the inner tailgate which is the smaller section of the tailgate on top that is able to fall down but the main gate will not. The inner tailgate has latch points on the right and on the left. if you take a hairdryer or heat gun and heat up those two areas you will have a fix to your problem. After being in cold temperature with snow and ice I believe what is happening is that condensation or moisture gets in those areas around the sensor and either refreezes or frosts over causing an error in the computer thinking that the tailgate is open. Four times now we have tried the solution and it works like a charm every time. I bet you will see the correlation between dry days with no snow or ice and days that have it causing the error. I hope this helps everyone understand what’s going on or find a way to explain it to a technician.