need a couple of bricks under the tyre so you don't roll awayI don't think the transmission gives any warning for fluid level like the engine will for oil or coolant. I would check the fluid level if nothing shows on the end of the stick then it's low for sure. Also you can disconnect the shifter cable and move it by hand p/r/n/d/l, get a helper and try it by hand in case your not adjusted on the cable correctly.