Begin with simple. For the beginning create or buy programmer,
which reads 93Cxx, 24xx, CXK10xx, X2444, SDE2506.
These EEPROM most frequently meet in car radio .
The information on programmers and chips suffices in a web.
For example same PONNYprog.
Basically in simple car radio having external EEPROM,
the code is written in it. There is also counter of attempts.
The code happens write down in an obvious kind,
and it happens and with encryption.
The hardware may be comes across, where the code is written down in MCU,
and the counter of attempts is in EEPROM.
It is possible to do them or serially substituting all variants of a code
( It is better for this purpose to use the PC),
or if it will be possible to read ROM,
under condition of if not set protection, and use disassembled MCU dump.
As to car radio based on Motorola - it is more difficult.
All is inside. But they are done also.
But for this purpose it is necessary to study a lot of technical literature.
The list is attached here.
To be continue . . .