I recently changed my alternator, battery, and main relay fuse, and I'm still only getting 13.5 (off the stock gauge) with NOTHING electrical on, and about 12.2 with headlights and radio on. It dips below 12 with the rear defroster or hazards or wipers or brakes pushed or logicon on. I'm aware that FCs have bad charging systems, but is this what any of you are experiencing? 88 SE basically stock (well, nothing electrically is aftermarket.) Any advice?

 

The stock gauges are not the most accurate under the sun. I suggest taking your car down to one of the local national chain car part places and have them do the test with good equipment. Or use a Digital Multi Meter and check the voltage, do not attempt to check the amps because a DVOM is only rated for about 10 amps then a fuse blows



Possible problems:



Dirty connections, and corroded cables



bad grounds, take the alternator off and clean the mounting area where it bolts to the engine to make sure there is a good clean ground.



the S4 has a weak alternator to begin with, so an upgrade to a S% or FD alternator might be a better option for you.

 

thanks Camel