Auto transmission PRND321 vs M+-


You might have noticed that in some automatic transmission cars the gator shows PRND321 where as some shows manual + – mode. So what dictates which one you will get?

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The PRND321 mode is usually featured when the car has traditional 4-speed torque converter type transmission. Since there are just 4 gears which you can cycle thru, it is convenient to explicitly display which one you have selected.

In many automatic cars, especially automated manuals where there are 5 or higher gears, it will be difficult to show all gear positions because it would make the gator quite longer or wider. Thus, just the manual mode (with M indicator) is shown with gator position for + and -. To up shift you push the gator to + slot and to downshift use the – slot.

The following picture shows how the gear selector would have to travel further if PRND321 style is used for many gears.

 

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One Response to “Auto transmission PRND321 vs M+-”

  1. Anonymous Says:

    The issue is that 3 2 1 are not gears, but ranges in which transmission operates.

    Remember that a classic 4 speed transmission usually lacks any engine braking in lower gears when operated in D, that’s why these ranges are necessary when driving in certain conditions.

    3 – is commonly known as tow/haul, when heavily laden and fourth overdrive gear is not necessary, whilst engine braking at cruising speed is.

    2 – manual second, for starting and driving low traction conditions (on ice, snow, mud).

    1- manual low, is descending steep grades.

    Modern transmissions have a great degree of electronic control, which makes some of these ranges obsolete, as these will be automatically selected if the conditions are required to do so.

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