Left Multi-Function Switch: Operation

The left multi-function switch uses a combination of resistor multiplexed switched outputs to control the many functions and features it provides using a minimal number of hard wired circuits. Following are descriptions of how the left multi-function switch operates to control the many exterior lighting functions and features it provides:

1. Auto Headlamps  - The automatic headlamps feature is provided by the Front Control Module (FCM), which monitors an input from a photodiode sensor located on the top of the instrument panel to detect ambient light levels whenever the ignition switch is in the On position. Based upon the multiplexed input from the left multi-function switch and the input of the photodiode sensor, the FCM controls outputs to the park lamp and headlamp relays to illuminate or extinguish all exterior lighting.
2. Front Fog Lamps  - The FCM monitors the left multi-function switch then, based upon that multiplexed input, controls an output to the front fog lamp relay to illuminate or extinguish the front fog lamps.
3. Headlamps  - The FCM monitors the left multi-function switch then, based upon that multiplexed input, controls an output to the headlamp low or high beam relays to illuminate or extinguish the headlamps.
4. Headlamp Beam Selection  - The FCM monitors the left multi-function switch then, based upon that multiplexed input, controls an output to the headlamp low or high beam relays to activate the selected headlamp beam.
5. Headlamp Optical Horn  - The FCM monitors the left multi-function switch then, based upon that multiplexed input, controls an output to the headlamp high beam relay to activate the headlamp high beams.
6. Park Lamps  - The FCM monitors the left multi-function switch then, based upon that multiplexed input, controls an output to the park lamp relay to illuminate or extinguish the parking lamps.
7. Turn Signal Control  - The left multi-function switch control stalk actuates the turn signal switch. The FCM monitors the left multi-function switch then, based upon that multiplexed input, provides a variable voltage output to control the lighting of the turn signals.

Following are descriptions of the how the left multi-function switch operates to control the many interior lighting functions and features it provides:

1. Panel Lamps Dimming  - The FCM monitors the left multi-function switch then, based upon that multiplexed input, provides a variable voltage output through several panel lamps driver circuits to control the lighting of many incandescent panel lamps. The FCM also sends panel lamps dimming messages over the Controller Area Network (CAN) data bus to other modules to control display lighting levels in those modules.
2. Interior Lamps Defeat  - The FCM monitors the left multi-function switch then, based upon that multiplexed input, internally disables the function the FCM normally provides to control the illumination of the interior lamps.
3. Parade Mode  - The FCM monitors the left multi-function switch then, based upon that multiplexed input, provides a voltage output through several panel lamps driver circuits to control the lighting of many incandescent panel lamps. The FCM also sends panel lamps dimming messages over the CAN data bus to other modules on the bus to control lighting levels in those modules.
4. Interior Lamps On  - The FCM monitors the left multi-function switch then, based upon that multiplexed input, provides a control output to activate all of the interior lamp circuits.