Section 13-04: Charging System Gauge/Warning Indicator | 1993 Mustang Workshop Manual |
The voltmeter indicates battery voltage when the ignition is in the RUN
position (engine OFF). The needle will indicate within the NORMAL band during
vehicle operation. Fluctuation at idle is no cause for concern. Voltmeter is
not adjustable and should be replaced if inoperative. 
A red generator charge indicator is located in the instrument cluster. This indicator glows when there is no generator output.
If the system is working normally, the following conditions will be present:
If the charge indicator does not come on with the ignition switch in the
RUN position and the engine not running, check the 'I' circuit (ignition switch
to regulator 'I' terminal) for an open circuit or burned out charge indicator.
Replace the indicator, if necessary. 