Not an expert here, but 15 volts may be ok. The Haynes manual for Lincoln Town Car (1970-2001) says running voltage should be 14-15 volts. The spec sheet for the alternator I just installed in a 1988 TC listed regulator set point as 14.8v, idling with no accessories measured ~14.5v. The battery will only read 12v if the engine and all accessories are turned off. Nominal running voltage for a "12 volt" system is 13.5v or so. The relevant questions may be:
Has the charging voltage of your car changed recently?
Is 15v causing problems, like burned-out bulbs, etc.?
How accurate is your voltmeter?
If you haven't already, you might check some other cars' running voltage with your meter for comparison.
Nov 7, 2011 at 5:30 AM