ok i'm trying 0
this is only an example of the calculation on a mazda 3, I do not know if on the mazda 6 are the same bit to change
find my car is in line 7B7 01 02 bit 6 in B0.
so you have 7 B7 01 02 A5 04 03 80 08 F5.
F5 is the checksum, you have to calculate it every time there is a change in the line
A5 is B0, 04 is B1, 03 is B2, 80 is B3, 08 is B4 , F5 is the checksum.
A5 is in hexadecimal, you must convert it to binary: A5 = 10100101.
from left b0=1 b1=0 b2=1 b3=0 b4=0 b5=1 b6=0
to change b6 to 1 add 100000 + 10100101 in binary convert to hexa 40 +A5=E5
your new line is 7 B7 01 02 E5 04 03 80 08 35.
the checksum is : 7+B7+01+02+E5+04+03+80+08=35 in hexa.
I'm not sure that this is very clear but my level of English does not allow me more. :dunno: