I offered you this advice as an automotive professional. Many times in a forum format clients may not be aware of other options available to them and having your vehicle bought back is often times overlooked. I offered this advice because of the year of your vehicle and the fact that you had brought the vehicle in four times for the issue. Also please keep in mind this is a forum and most of the time a conversation must take place between the technician and the client in order to resolve the client's issue. With that being said, here as some possible failures that can be causing your particular issue.
A failing torque converter can begin to produce a howling noise in forward and reverse gears and in more extreme cases acceleration and deceleration.
A stuck valve in the velve body in the trans can create pressure and lubrication issues that often times will result in howling.
Also an extremely clogged trans filter can also create a similar issue however being that the vehicle is so new I would doubt this option.
I hope this was helpful.
Monday, February 2nd, 2009 AT 10:52 AM