Ford 2003 Mustang Workshop Manual page 3494

as detected by the door ajar circuit. For vehicles equipped with the remote keyless entry feature, any
signal the GEM detects when a valid remote transmitter button is depressed will reset both the
demand and courtesy lamp battery saver timers. This battery saver relay then restores power to both
the demand and courtesy lamp circuits.
Base Courtesy and Extended Lighting
The base courtesy lighting feature provides interior lighting for the convenience of the vehicle's
occupants. The courtesy lamps consist of the map/dome lamps for the coupe and the map lamps for
the convertible. All lamps designated as courtesy lamps will be illuminated whenever the GEM detects
that the driver or passenger doors become ajar, by means of the driver or passenger door ajar circuits.
The courtesy lamps will also be illuminated when the GEM detects that the dome lamp switch has
been activated, by means of the dome lamp switch circuit.
The extended courtesy lighting feature provides temporary extended illumination of the courtesy lamps
after the customer has entered the vehicle. The courtesy lamps will remain illuminated for 25 seconds
after the GEM detects that the driver and passenger doors are closed, as detected by the door ajar
circuits. The extended courtesy lighting feature will be terminated after the 25 second time-out period,
or if the GEM detects that the ignition switch has been moved from the OFF position to either the RUN,
ACC, or START positions.
Demand Lighting
The GEM does not provide any special features to the demand lighting group with the exception of
providing a power source when the battery saver feature is active. The demand lighting group consists
of the luggage compartment lamp, the driver and passenger vanity mirror lamps, and the map lamps.
Illuminated Entry with Remote Keyless Entry
The illuminated entry with remote keyless entry feature, provides power to the courtesy lamps when
the remote transmitter is used. When the GEM detects that the ignition switch is in the OFF or key out
positions, and it detects that a valid remote transmitter unlock button has been depressed, power to
the courtesy lamps will be enabled. The courtesy lamp circuit will remain powered until one of the
following occurs:
The GEM detects that the ignition switch has been moved from the OFF, to the RUN, START,
or ACC position.
The GEM detects any valid remote transmitter lock button is depressed.
The courtesy lamp circuit has been powered for 25 seconds.
If the GEM detects any valid remote transmitter unlock button has been depressed, and the ignition
switch is in the OFF or key out position during the 25 second time-out, the courtesy lamp circuits will
remain powered for an additional 25 seconds.
Inspection and Verification
1. The interior lighting system is a generic electronic module (GEM) controlled system.
2. Verify the customer concern by operating the interior lighting system.
3. Visually inspect for the following obvious signs of mechanical and electrical damage.