cadillac seville 1993

after 3 days of running my cad with the service engine soon
it fails to charge and i have no reading for the gas gauge or
volts. when i turn on the ignition i don't have any usual ligths coming in.
(ex service engine, abs or anything) however, it starts and drives good
but isn't charging.

whats the possibilities of a bad alternator is causing the problems?

or maybe my computer went bad?

could it be an specific losse ground ?

i already try reading the pcm codes by groundig A and B at the
computer terminal under dash. nothing happened

i already disconected the negative battery terminal to get al codes clear, nothing happened.

two weeks ago the injectors were sevice.