Assuming you mean selecting "1" or "2" on the gear shift lever (which selects first second gear, respectively)... You can downshift to 2nd, or even 1st to help slow down (or to stay slower while going down a hill) with a load.
What are the gears for in an automatic car?
The different gears are sometimes called the sun gear, the ring gear, and the planetary gear. The arrangement of the gears determines how much power will flow from one gear to another and out to the drive train of the vehicle when you shift.13 abr 2020
The gear indicator scans a vehicle's CAN bus and displays current gear data allowing technicians and vehicle operators to monitor the actual current gear used by the transmission, not just the lever position. The data is displayed on a 5×8 LED dot-matrix display housed in a rugged plastic enclosure.
D3 is drive, limited to the third gear as the highest gear possible, typically. See “3, 2, & 1” below. D2 is also drive, but limited to only first & second gears possible, typically. See “3, 2, & 1” below.
The gear shift indicator notifies the driver when it is appropriate to engage the next higher or lower gear in order to obtain the lowest possible fuel consumption. An essential detail in connection with environmental driving is to drive in the right gear and to change gear in plenty of time.31 ene 2020
The D1, D2, D3 gears can be used in place of the brakes. On the occasions like you are experiencing a downhill or approaching red lights and you don't want to apply the brake, these D options are for you. So basically, this can come handy if you need to slow down the vehicle when your car suffers brake failure.6 jun 2018