Originally Posted by Lois L
Read through the owners manual quite a few times, it just says put gear shift lever in the "M" position, then use + or - to shift up or down. No great detail at all. Yes, it did go into 4 by itself, my sisters witnessed it, so I plan on taking it in. Bought the extended warranty, so why not use it, right? Older cars were so much simpler... *sigh* Thank you all.
I looked up your owner's manual online, and you're right- it doesn't say much. In any case, it's probably a good idea to take it in. It should only move one gear at a time with the +/- buttons. When you're discussing the problem with the service advisor, you can pick his/her brain about the best way to use the transmission when towing. Let them know it's a fairly light
trailer (1500-1800 pounds loaded).
The manual supports what others have said and only mentions downshifting on hills (in the towing section). With a small trailer in normal conditions on flat(ish) terrain, you should be fine to leave it in D. When climbing or descending a grade, that's the time to put in M and downshift. I would do it that way when you pull the trailer home this weekend.
Best wishes with your new Casita! All this uncertainty will sort itself out. My mother's RV also has an 8-speed transmission with a manual mode like yours. I had to help her figure that out so we could caravan to a campsite through a steep winding canyon. She did fine. You will, too.