I HAVE A 1990 SILVERADO WITH A 350 AND I HAVE REPLACED BATT. AND ALT.BECAUSE OF THE CHARGING GAUGE IS READING VERY LOW AND ALSO BATT. LIGHT COMES ON. IT IS STILL THE SAME WAY AFTER THE REPLACEMENTS.THERE IS ONE ODD THING THE GAUGE WILL ONLY READ LOW WHEN ITS COLD THEN AFTER IT WARMS UP 5-10 MIN. IT READS NORMAL ANYONE HAVE ANY IDEAS

 

throw a volt meter on it, anything over 12 volts is charging but it should be around 14.4 might have a bad cable somewhere,also clean all connections.

 

also do you have the external votage regulator or the internal on on the aternator those go bad a lot.