Hard for comunication, you need good interface.
tachopro interface won't to talk.

Audi A3 1998
MCU HC11E20 64 QFP
Must lift from a board:
pin 25 MODB   (on board is conected direct to Vdd)
pin 43 Reset
pin 47 RxD
pin 50 TxD

Gopel Audi Bosh do not work with this MCU.
Software coding 00004
Airbag Audi6 D01

Airbag modul have 50pins
pin5   +12V
pin6   GND
pin9   K line