Principles of Operation: Autolamps

WARNING: This page is about a different car, the 2002 Lincoln LS. However, it is still accessible from the selected car via links, so may be relevant.

The autolamps are controlled by the headlamp switch, autolamp sensor, instrument cluster module and the FEM. The headlamps may be in the high or low beam position depending on the multifunction switch position. When the headlamp switch is in the autolamp position, the instrument cluster module will send an ON or OFF command to the FEM, depending on the signal from the autolamp sensor. The FEM will process this information and output the appropriate command to the headlamps, which are hardwired to the FEM. The autolamps will remain ON for approximately 20 seconds after the ignition switch is changed from the RUN position to the ACC or OFF position.

Autolamps and daytime running lamps (DRL) are two functions which the FEM may be configured to include.

Left and right low, as well as high beams will provide a lamp outage indication. Fault management of the headlamps will provide some headlamp functionality. In the event of all multifunction switch, all headlamp switch or ignition switch invalid or missing data failures, the low beams will be illuminated.

The vehicle's electronic functions are divided into zones. The FEM controls the front portion of the vehicle and the REM controls the rear portion of the vehicle. These systems rely heavily on the SCP communication network in order to transmit and receive signals. As a technician it is very important to understand:

Where the input (command) originates from.
All information (messages) necessary in order for a feature to operate.
Which module(s) receive(s) the input or command message.
Does the module which received the input (message), control the output of the feature, or does it output a message over the SCP communication network to another module.
Which module controls the output of the feature.