Can a bad battery affect the PCM 1997 Cadillac deville?

Question

Codes PO300, P1660 Changed all three cooling fan relays, new coils, plug and wires. A/c won't  work also! Can anyone help?

Answer 1

P0300 Random  misfire

P1660 Cooling fan relay control circuit

The cooling fan control relay receives its ground from the PCM if the PCM does not send the ground to the cooling fan relay you will not have a working a/c unit .and  a working cooling fan. If there is no ground from the PCM  . This would be a PCM problem , Yes a bad battery can affect the PCM . A good battery is able to ground a/c ripples that are created by the charging system, if the ripples are allowed to be excessive you can ruin the PCM.