I have a small question. It may seem dumb, but I do not know the answer right off. Our TD has 19,000 miles on it. In the warm weather the turbo kicks in, but in this cool weather it does not. I am understanding it has to be hot for the trubo to kick in. Ex:we were towing our tt (7000 lbs) home from the hills. Outside temperature was in the upper 60's. I never heard our trubo kick in 150 miles. How come??????