Strange Humming Noise
 

Hi all, I have had my truck for a little over 2 years now and about a year ago i notices a slight hum when I pressed the gas and I was between 70 km/h and 80 km/h. I found that it never cause any decrease in performance or functionality, so i just ignored it. As of 2 weeks ago I noticed that when it was really cold outside (-25C) the hum gets louder and the truck doesn't want to shift into 4th gear. Could these 2 be related and what could be the problem/s?

Go to dodgeforum.com others talk about that humming noise. I don't think they are supposed to shift to 4th and 5th until they warm up. Mine doesn't shift to 4th until about 4 miles or so.(only when it is cold out.) Mine only makes a humming noise when I barely have foot on gas at around 50 to 55 mph.