Left Multi-Function Switch: Operation

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

• Auto Headlamps  - The automatic headlamps feature is provided by the Body Control Module (BCM), which monitors an input from a photodiode sensor located in the Electrocromatic Mirror (ECM) 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 BCM controls outputs to the park lamp and headlamp relays to illuminate or extinguish all exterior lighting.
• Front Fog Lamps  - The Body Control Module (BCM) monitors the left multi-function switch then, based upon that switched ground input, controls an output to the front fog lamp relay to illuminate or extinguish the front fog lamps.
• Headlamps  - The Body Control Module (BCM) 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.
• Headlamp Beam Selection  - The Body Control Module (BCM) monitors the left multi-function switch then, based upon that switched ground input, controls an output to the headlamp low or high beam relays to activate the selected headlamp beam.
• Headlamp Optical Horn  - The Body Control Module (BCM) monitors the left multi-function switch then, based upon that switched ground input, controls an output to the headlamp high beam relay to activate the headlamp high beams.
• Park Lamps  - The Body Control Module (BCM) 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.
• Turn Signal Control  - The left multi-function switch control stalk actuates the turn signal switch. The Body Control Module (BCM) 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.

  The left multi-function switch operates to control the many interior lighting functions and features it provides:

• Panel Lamps Dimming  - The Body Control Module (BCM) 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 BCM also sends panel lamps dimming messages over the Programmable Communications Interface (PCI) data bus to other modules to control Display lighting levels in those modules.
• Interior Lamps Defeat  - The Body Control Module (BCM) monitors the left multi-function switch then, based upon that multiplexed input, internally disables the function the BCM normally provides to control the illumination of the interior lamps.
• Interior Lamps On  - The Body Control Module (BCM) monitors the left multi-function switch then, based upon that multiplexed input, provides a control output to activate all of the interior lamp circuits.
• Parade Mode  - The Body Control Module (BCM) 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 BCM also sends panel lamps dimming messages over the Programmable Communications Interface (PCI) data bus to other modules on the bus to control lighting levels in those modules.