well they are all linked together imo
TC runs off ABS unit and they talk to the ECM to remove power when needed
do a search on the site and their is another user with p0602 code relating to a battery change
clear down codes and if they re appear and switch on MIL light then further investigation is needed
bottom line is if engine ecu is knackered then cos this engine is aging then 2nd hand parts are cheaper - ecu with transponder and chip is about £100
TIS says if p0601 or p0604 is not also stored and you have an active code in p0602 then the ecu needs to be reprogrammed