Could a bad battery or a battery on its way out cause the check engine light to come on? Have not checked codes. Could have a problem with voltage regulator, possibly a stator (hope not!!) 2002 FLSTCI, speedo looses power comes back. Just troubleshooting. Or would a bad battery cause the lose of power to speedo as well. Going to have battery checked and put a meter on the voltage regulator. THX for any thoughts.