Toyota Repair: truck vibrates at 35-40 mph, electrical problem, transmission problem

Question
I have a 2006 tundra dc v8 4x4 and if i don't turn off the overdrive the truck vibrates at 35-40 mph when going into overdrive. Is this an electrical problem ? Any help thanks M.

Answer
If it only vibrates when shifting into overdrive it may be a transmission problem, an electronic control malfunction would turn the check engine light on, I assume this is not the case since you did not mention it, the first thing I would do is to check the transmission fluid, this transmission has no dipstick but the fluid can be checked using a Toyota diagnostic tool so you may have to get the dealer involved, it may also help to change the fluid if it has close to 80,000 miles, I know it is supposed to be "lifetime" fluid but most dealers recommend replacing the fluid at the most at 100,000 miles.