i have a 2007 grand prix, it started out with the blower motor not stopping with the key off, changed the resistor and motor and fixed. now the fan motor will go on and off on its own with a multimeter I notice when the power dips below 11.6 volts it shuts off and the dome lights dim, it will come back on once it goes above 11.6 I have replaced the battery (corrosion and noticed swelling on the top). I take the wire off the alternator heck the voltage and it is 15 volts put it on and 14.6 normal but still cab voltage is low .when the fan is working and I put it in reverse, drive, turn on the rear defroster or use anything in the cab that requires voltage it goes off for a few seconds till it has enough voltage to run again. any suggestions would be much appreciated