Same issue. 2006 SCREW 4x4 - Only happens when temp is down in the freezing range.
Originally Posted by nashtruck
I have had the same problem for four winters now and it is definatley not the alternater. Its a whistle, not a squeal. It only happens sometimes in cold weather. It did happen this morning but after driving a few blocks it stopped. Tried having the dealer look at it under warranty but of course...no whistle that day! I would love an answer to this.