Salam
There r three gear levels (L, 2, D). L means gear #1 as in manual, 2 means 2nd n D means 3rd n above speed in manual.
There is a card having around 15 pin conector just like those in a pc, this conector wen conected to the male conector which goes some where in engine. In this scenario wen i put the car in D gear the car run in the speed of 1st gear then shifts to the third gear n skiping the 2nd gear, so the speed gain very slowly after shifting to third.
On the other hand wen i remove the above conector, i put gear in L n gain speed upto 30 n shifts manually the lever to 2 the speed increases up n then at near 60 i change the gear manually to D the speed gain further. This way i manually shift the lever up or down to inc or at dec speed.