Durango 2WD V8-4.7L (2008)
Combination Switch: Description and Operation
Operation
OPERATION
The multi-function switch uses resistor multiplexing to control the many functions and features it provides using only three hard wired output circuits.
The switch receives a clean ground from the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) on a
multi-function switch return circuit. It then provides outputs to the EMIC on a wash/beam select switch signal circuit to control front washer and
headlamp beam selection, on an intermittent wiper switch signal circuit to control front wipers, and on a turn lamps switch signal circuit to control turn
signal and hazard warning functions.
The multi-function switch operates as follows:
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Front Washer Control - The control knob on the end of the multi-function switch control stalk is depressed towards the steering column to
momentarily activate the washer pump in the front WASH mode. The washer pump will continue to operate in the front washer mode until the
control knob is released or for 10 continuous seconds, whichever occurs first. The multi-function switch provides an output to the EMIC, and the
EMIC responds by sending electronic front washer switch status messages to the Front Control Module (FCM) over the Controller Area
Network (CAN) data bus. The FCM responds by energizing or de-energizing the washer pump in the front washer mode.
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Front Wiper Control - The control knob on the end of the multi-function switch control stalk is rotated to one of the continuous front wiper
detents, to one of five intermittent wiper detents, or to the OFF position to select the front wiper mode. The multi-function switch provides an
output to the EMIC, and the EMIC responds by sending electronic front wiper switch status messages to the FCM over the CAN data bus. The
FCM responds by energizing or de-energizing the wiper on/off and high/low relays in the Power Distribution Center (PDC) for front wiper system
control.
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Hazard Warning Control - The hazard warning push button of the multi-function switch is depressed to activate the hazard warning system, and
depressed again to turn the system OFF. When the push button is actuated, the multi-function switch provides an output to the EMIC, and the
EMIC responds by sending electronic hazard switch status messages to the FCM over the CAN data bus. The FCM then energizes and flashes or
de-energizes both the left and right turn signal circuits to provide the visual hazard warning.
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Headlamp Beam Selection - The control stalk of the multi-function switch is pulled towards the steering wheel past a detent to actuate the
integral beam select switch circuitry, or to an intermediate, momentary position before the detent to actuate the optical horn feature. Each time the
control stalk is actuated to a detent position, the opposite headlamp beam from what is currently selected will be energized. Each time the control
stalk is actuated to the momentary position with the headlamps turned OFF, the headlamp high beams will be illuminated for as long as the control
stalk is held in this position. The multi-function switch provides an output to the EMIC, and the EMIC responds by sending electronic beam select
switch status messages to the FCM over the CAN data bus. The FCM energizes or de-energizes the selected LOW or HIGH beam circuits.
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Turn Signal Control - The control stalk of the multi-function switch is moved upward to activate the RIGHT turn signal circuitry, and,
downward to activate the LEFT turn signal circuitry. The turn signal switch has a detent position in each direction that provides turn signals with
automatic cancellation, and an intermediate, momentary position in each direction that automatically provides three turn signal blinks as a LANE
CHANGE feature when the control stalk is tapped or will energize the turn signals for as long as the control stalk is held in the momentary
position. When the control stalk is moved to a detent turn signal switch position, the cancel actuator extends toward the center of the steering
column. A turn signal cancel cam that is integral to the clockspring rotates with the steering wheel and the cam lobes contact the cancel actuator
when it is extended from the multi-function switch. When the steering wheel is rotated during a turning maneuver, one of the two turn signal cancel
cam lobes will contact the turn signal cancel actuator. The cancel actuator latches against the cancel cam rotation in the direction opposite that
which is signaled. If the LEFT turn signal detent is selected, the lobes of the cancel cam will ratchet past the cancel actuator when the steering
wheel is rotated to the left, but will unlatch the cancel actuator as the steering wheel rotates to the right and returns to center, which will cancel the
turn signal event and release the control stalk from the detent so it returns to the neutral OFF position. When a turn signal is activated, the
multi-function switch provides an output to the EMIC, and the EMIC responds by sending electronic turn signal switch status messages to the
FCM over the CAN data bus. The FCM energizes and flashes or de-energizes the selected left or right turn signal circuits.
The multi-function switch as well as the hard wired inputs and outputs of the switch may be diagnosed using conventional diagnostic tools and
procedures. Refer to the appropriate wiring information.
