Hi!
I recently purchased a Jeep Grand Cherokee with a 4.0L engine and automatic transmission (42RE).

Sometimes I drive on roads and I would like to use the engine brake more, but the automatic transmission lets the car accelerate. I know gears 1 and 2 are to prevent the car from accelerating or to haul loads, but I'm not sure if I can shift from D to 2 while driving or if this could be harmful to the transmission.

Greetings and apologies for my level of English, I am Spanish

 

Welcome to the forum. The answer is yes. Your transmission always cycles itself between gears based on speed, throttle position and some internal things happening. So if you are going downhill, yes you can shift down to use engine compression to apply some braking. If you are going too fast for that gear, it will not shift down. I so this all the time on various transmissions I have

 

Thank you so much!

 

Indeed, I often place my transfer case in 4-Low and use the lower gears on my AW-4 when descending steep trails to hold the speed down and save my brakes from overheating.