Hazard Warning Switch: Description and Operation
Fig.21 Hazard Switch:
HAZARD SWITCH
The hazard switch is integral to the hazard switch module, which is secured near the center of instrument panel just above the radio. Only the hazard switch button is visible through a dedicated, round, beveled opening on the outer surface of the instrument panel between the two center panel outlets of the heater and air conditioning system. A red, stencil-like International Control and Display Symbol icon for "Hazard Warning" identifies the hazard switch button. On the opposite end of the black, molded plastic hazard switch module housing from the switch button is an integral connector receptacle and a stamped steel mounting bracket with two latch feature tabs that extend downward, while a short dowel-like alignment pin is integral to each side of the housing just below the switch button. The switch module is connected to the vehicle electrical system through a dedicated take out and connector of the instrument panel wire harness. Within the hazard switch module housing is the hazard switch circuitry and an electronic circuit board with the integral combination flasher circuitry The electronic combination flasher circuitry performs both the hazard flasher and turn signal flasher functions.
The hazard switch module cannot be adjusted or repaired and, if faulty or damaged, the unit must be replaced.
The hazard switch button is slightly recessed in the instrument panel when the switch is in the OFF position, and latches at a position that is flush with the outer surface of the instrument panel when in the ON position. The hazard switch module produces an audible clicking sound that emulates the sound of a conventional flasher whenever the turn signals or the hazard warning system are activated. The hazard switch module receives battery current on a fused B(+) circuit from a fuse in the Junction Block (JB) at all times for operation of the hazard warning, and on a fused ignition switch output (run) circuit from another fuse in the JB whenever the ignition switch is in the ON position for operation of the turn signals. The module receives a path to ground through a splice block located in the instrument panel wire harness with an eyelet terminal connector that is secured by a nut to a ground stud on the driver side instrument panel end bracket near the JB. Inputs to and outputs from the hazard switch module include:
- Panel Lamps Dimmer Input - A non-service- able incandescent bulb soldered onto the hazard switch module circuit board provides illumination of the switch button when the exterior lighting is turned ON through an input received on the fused panel lamps dimmer switch signal circuit. However, this bulb flashes ON and OFF at full intensity whenever the hazard switch button is in the ON position, regardless of the status of the exterior lighting.
- Hazard Switch Input - The combination flasher circuitry of the hazard switch module receives an internal ground input from the hazard switch to request hazard flasher operation.
- Multi-Function Switch Input - The combination flasher circuitry of the hazard switch module receives separate ground inputs from the turn signal switch circuitry of the multi-function switch on right and left turn switch sense circuits to request right or left turn signal flasher operation.
- Body Control Module Input - The Body Control Module (BCM) can request hazard flasher operation by providing a ground path to the combination flasher circuitry of the hazard switch module through a hazard lamp control circuit.
- Turn Signal Output - The combination flasher circuitry within the hazard switch module responds to the flasher request inputs by energizing and de-energizing two miniature relays on the module circuit board. These relays control the switch output through the right and left turn signal circuits. One relay controls the right lamps, while the other controls the left.
Because of active electronic elements within the hazard switch module, it cannot be tested with conventional automotive electrical test equipment. If the hazard switch module is believed to be faulty, replace the switch with a known good unit to confirm system operation.
Fig.50 Multi-Function Switch:
MULTIFUNCTION SWITCH
The multi-function switch is located on the steering column, just below the steering wheel (Fig 50). The only visible components of the multi function switch are two levers, or control stalks that extend through dedicated openings in each side of the steering column shrouds. The remainder of the switch, its mounting provisions, and its electrical connections are all concealed beneath the steering column shrouds. The switch housing and controls are constructed of molded black plastic. A saddle-like formation in the center of the multi-function switch housing straddles the steering column tube just below the column lock housing, and two posts integral to the lower surface of the switch housing engage two holes on the forward-facing side of the lock housing. Two integral ledge-like locating tabs near the top of the rearward facing switch housing surface are supported and located by two upright stanchions that extend upward from the top of the lock housing. Also on the rearward facing switch housing surface near the center, an integral ledge- like mounting tab rests on a similar ledge-like tab that extends from each side of the steering column lock housing. When the steering column shrouds are installed on the column, the switch mounting tabs are clamped along with the mounting tabs of the clockspring between the integral mounting stanchions of the upper shroud and the lock housing tabs, and are secured to the steering column lock housing by the same two screws that secure the two shroud halves to each other and the column.
There are several versions of the multi-function switch to support both optional equipment and equipment that is required only in certain markets. Each multi-function switch control stalk has both white nomenclature and International Control and Display Symbol graphics applied to it, which clearly identify its many functions. Each control stalk has a control knob on its end with a flattened face to allow it to be easily rotated. On vehicles equipped with optional front fog lamps, the knob on the end of left control stalk can also be pulled outward to select those lamps. Each control stalk also features a knurled control ring located just below the control knob. The left control stalk is dedicated to providing driver controls for the interior and exterior lighting systems, while the right control stalk is dedicated to providing driver controls for the front and rear wiper systems. Two integral connector receptacles on the forward facing surface of the multi-function switch housing connect the switch two the vehicle electrical system through two take outs and connectors of the instrument panel wire harness. The left connector receptacle contains nine terminal pins for the lighting control circuits of the switch, while the right connector receptacle contains six terminal pins for the wiper control circuits of the switch. The multi-function switch cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
LEFT CONTROL STALK The left (lighting) control stalk of the multi-function switch supports the following functions and features:
- Front Fog Lamps - For vehicles so equipped, the internal circuitry and hardware of the multi- function switch left (lighting) control stalk provide detent switching for the optional front fog lamps.
- Headlamps - The internal circuitry and hardware of the multi-function switch left (lighting) control stalk provide detent switching for the headlamps.
- Headlamp Beam Selection - The internal circuitry and hardware of the multi-function switch left (lighting) control stalk provide detent switching for selection of the headlamp high or low beams.
- Headlamp Optical Horn - The internal circuitry and hardware of the multi-function switch left (lighting) control stalk includes momentary switching of the headlamp high beam circuits to provide an optical horn feature (sometimes referred to as flashto-pass), which allows the vehicle operator to momentarily flash the headlamp high beams as an optical signalling device.
- Interior Lamps Defeat - The internal circuitry and hardware of the multi-function switch left (lighting) control stalk provide detent switching to defeat the illumination of all interior courtesy lamps when a door, the rear flip-up glass, or the tailgate are opened.
- Interior Lamps ON - The internal circuitry and hardware of the multi-function switch left (lighting) control stalk provide detent switching to simultaneously illuminate all interior courtesy lamps.
- Panel Lamps Dimming - The internal circuitry and hardware of the multi-function switch left (lighting) control stalk provide simultaneous adjustable control of the illumination intensity of all instrument panel lighting at one of six available illumination intensity levels.
- Parade Mode - The internal circuitry and hardware of the multi-function switch left (lighting) control stalk provide detent switching for a parade mode that maximizes the illumination intensity of all instrument panel lighting for visibility when driving in daylight with the exterior lamps turned ON.
- Park Lamps - The internal circuitry and hardware of the multi-function switch left (lighting) control stalk provide detent switching for the park lamps.
- Rear Fog Lamps - For vehicles so equipped, the internal circuitry and hardware of the multi- function switch left (lighting) control stalk provide detent switching for the optional rear fog lamps. Rear fog lamps are optional only for vehicles manufactured for certain markets, where they are required.
- Turn Signal Control - The internal circuitry and hardware of the multi-function switch left (lighting) control stalk provide both momentary non-detent switching and detent switching with automatic cancellation for both the left and right turn signal lamps.
RIGHT CONTROL STALK The right (wiper) control stalk of the multi-function switch supports the following functions and features:
- Continuous Front Wipe Modes - The internal circuitry and hardware of the multi-function switch right (wiper) control stalk provide two continuous front wipe switch positions, low speed or high speed.
- Continuous Rear Wipe Mode - The internal circuitry and hardware of the multi-function switch right (wiper) control stalk provide one continuous rear wipe switch position.
- Front Washer Mode - The internal circuitry and hardware of the multi-function switch right (wiper) control stalk switch provide front washer system operation.
- Front Wipe-After-Wash Mode - The internal circuitry and hardware of the multi-function switch right (wiper) control stalk provide a wipe-after-wash mode.
- Front Wiper Mist Mode - The internal circuitry and hardware of the multi-function switch right (wiper) control stalk provide a front wiper system mist mode.
- Intermittent Front Wipe Mode - The internal circuitry and hardware of the multi-function switch right (wiper) control stalk provide an intermittent front wipe mode with five delay interval positions.
- Intermittent Rear Wipe Mode - The internal circuitry and hardware of the multi-function switch right (wiper) control stalk provide one fixed interval intermittent rear wipe mode switch position.
- Rear Washer Mode - The internal circuitry and hardware of the multi-function switch right (wiper) control stalk provide rear washer system operation.
The multi-function switch uses a combination of resistor multiplexed and conventionally switched outputs to control the many functions and features it provides. The switch receives battery current on a fused ignition switch output (run-acc) circuit from a fuse in the Junction Block (JB) whenever the ignition switch is in the ON or Accessory positions. The switch receives a path to ground at all times through a splice block located in the instrument panel wire harness with an eyelet terminal connector that is secured by a nut to a ground stud on the driver side instrument panel end bracket near the Junction Block (JB). Following are descriptions of how each of the two multi-function switch control stalks operate to control the functions and features they provide.
LEFT CONTROL STALK The left (lighting) control stalk of the multi-function switch operates as follows:
- Front Fog Lamps - For vehicles so equipped, the control knob on the end of the multi-function switch left (lighting) control stalk is pulled outward to activate the optional front fog lamps. The control knob is mechanically keyed so that it cannot be pulled outward unless it is first rotated to turn ON the exterior lighting. The multi-function switch provides a resistor multiplexed output to the Body Control Module (BCM) on a fog lamp switch sense circuit, and the BCM responds by energizing or deenergizing the front fog lamp relay in the Junction Block (JB) as required.
- Headlamps - The control knob on the end of the multi-function switch left (lighting) control stalk is rotated forward (counterclockwise) to its second detent position to activate the headlamps. The multi- function switch provides a resistor multiplexed output to the Body Control Module (BCM) on a headlamp switch sense circuit, and the BCM responds by energizing or de-energizing the selected low or high beam relay (Daytime Running Lamp relay in Canadian vehicles) in the Junction Block (JB) as required.
- Headlamp Beam Selection - The left (lighting) control stalk of the multi-function switch is pulled towards the steering wheel past a detent to actuate the integral beam select switch circuitry. Each time the control stalk is activated in this manner, the opposite headlamp beam from what is currently selected will be energized. The multi-function switch provides a ground output to the Body Control Module (BCM) on a high beam switch sense circuit, and the BCM responds by energizing or de-energizing the selected low or high beam relay (Daytime Running Lamp relay in Canadian vehicles) in the Junction Block (JB) as required.
- Headlamp Optical Horn - The left (lighting) control stalk of the multi-function switch is pulled towards the steering wheel to just before a detent, to momentarily activate the headlamp optical horn feature. The high beams will remain illuminated until the control stalk is released. The multi-function switch provides a ground output on a high beam relay control circuit to energize the headlamp high beam relay (Daytime Running Lamp relay in Canadian vehicles) in the Junction Block (JB) as required.
- Interior Lamps Defeat - The control ring on the multi-function switch left (lighting) control stalk is rotated to a full rearward (clockwise) detent to defeat the illumination of all interior courtesy lamps. The multi-function switch provides a resistor multiplexed output to the Body Control Module (BCM) on a panel lamps dimmer switch mux circuit, and the BCM responds by de-energizing its internal courtesy lamp driver circuit.
- Interior Lamps ON - The control ring on the multi-function switch left (lighting) control stalk is rotated to a full forward (counterclockwise) detent to illuminate all interior courtesy lamps. The multi- function switch provides a resistor multiplexed output to the Body Control Module (BCM) on a panel lamps dimmer switch mux circuit, and the BCM responds by energizing its internal courtesy lamp driver circuit.
- Panel Lamps Dimming - The control ring on the multi-function switch left (lighting) control stalk is rotated to one of six minor intermediate detents to simultaneously select the desired illumination intensity of all adjustable instrument panel and instrument cluster lighting. The control ring is rotated rearward (clockwise) to dim, or forward (counterclockwise) to brighten. The multi-function switch provides a resistor multiplexed output to the Body Control Module (BCM) on a panel lamps dimmer switch mux circuit, and the BCM responds by sending an electronic panel lamps dimming level message to the ElectroMechanical Instrument Cluster (EMIC) over the Programmable Communications Interface (PCI) data bus. The EMIC electronic circuitry then provides the proper PWM output to the cluster illumination lamps and the VFD on the EMIC circuit board, then provides a matching PWM output on the hard wired fused panel lamps dimmer switch signal circuit.
- Parade Mode - The control ring on the multi- function switch left (lighting) control stalk is rotated to an intermediate detent that is one detent rearward (clockwise) from the full forward (counterclockwise) detent to select the Parade mode. The multi- function switch provides a resistor multiplexed output to the Body Control Module (BCM) on a panel lamps dimmer switch mux circuit, and the BCM responds by sending an electronic panel lamps dimming level message to the ElectroMechanical Instrument Cluster (EMIC) over the Programmable Communications Interface (PCI) data bus. The EMIC electronic circuitry then provides the proper PWM output to the cluster illumination lamps and the VFD on the EMIC circuit board, then provides a matching PWM output on the hard wired fused panel lamps dimmer switch signal circuit to illuminate all lamps at full (daylight) intensity with the exterior lamps turned ON.
- Park Lamps - The control knob on the end of the multi-function switch left (lighting) control stalk is rotated forward (counterclockwise) to its first detent from the OFF position to activate the park lamps. The multi-function switch provides a resistor multiplexed output to the Body Control Module (BCM) on a headlamp switch sense circuit, and the BCM responds by energizing or de-energizing the park lamp relay in the Junction Block (JB) as required.
- Rear Fog Lamps - For vehicles so equipped, the control knob on the end of the multi-function switch left (lighting) control stalk is rotated forward (counterclockwise) to its third detent position to activate the rear fog lamps. The multi-function switch provides a resistor multiplexed output to the Body Control Module (BCM) on a headlamp switch sense circuit, and the BCM responds by energizing or deenergizing the rear fog lamp relay in the Junction Block (JB) as required. Rear fog lamps are optional only for vehicles manufactured for certain markets, where they are required.
- Turn Signal Control - The left (lighting) 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 provides turn signals only until the left multi-function switch control stalk is released. When the control stalk is moved to a turn signal switch detent 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 left 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. In other words, 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 a ground output on a right or left turn switch sense circuit to the combination flasher circuitry within the hazard switch, and the combination flasher flashes the turn signal lamps.
RIGHT CONTROL STALK The right (wiper) control stalk of the multi-function switch operates as follows:
- Continuous Front Wipe Modes - The control knob on the end of the multi-function switch right (wiper) control stalk is rotated to an intermediate detent that is one detent rearward (counterclockwise) from the full forward (clockwise) detent to select the low speed continuous front wiper mode, or to its full forward (clockwise) detent to select the high speed continuous front wiper mode. The multi-function switch provides a resistor multiplexed output to the Body Control Module (BCM) on a front wiper switch mux circuit, and the BCM responds by energizing the wiper ON/OFF relay in the Power Distribution Center (PDC) for the front low speed continuous wipe mode, or the wiper ON/OFF relay and the wiper high/low relay in the PDC for the front high speed continuous wipe mode as required.
- Continuous Rear Wipe Mode - The control ring on the multi-function switch right (wiper) control stalk is rotated to the most forward (clockwise) detent to select the continuous rear wiper mode. The multi-function switch provides a battery current output to the rear wiper motor on a rear wiper on driver circuit to signal the rear wiper motor to operate in the continuous wipe mode.
- Front Washer Mode - The right (wiper) control stalk of the multi-function switch is pulled towards the steering wheel to momentarily activate the washer pump in the front washer mode. The washer pump will continue to operate in the front washer mode until the control stalk is released. The multi- function switch provides a ground output on a washer pump sense circuit, and battery current on a washer pump driver circuit to energize the washer pump in the front washer mode.
- Front Wiper Mist Mode - The right (wiper) control stalk of the multi-function switch is pushed towards the floor to momentarily activate the front wiper motor in the mist mode. The front wiper motor will continue to operate in the mist mode until the control stalk is released. The multi-function switch provides a resistor multiplexed output to the Body Control Module (BCM) on a front wiper switch mux circuit, and the BCM responds by energizing the wiper ON/OFF relay in the Power Distribution Center (PDC) to operate the front wiper motor momentarily at low speed to provide the front wiper mist mode.
- Intermittent Front Wipe Mode - The control knob on the end of the multi-function switch right (wiper) control stalk is rotated to one of five minor intermediate detents to select the desired intermittent front wipe delay interval. The control knob is rotated rearward (counterclockwise) to increase the delay, or forward (clockwise) to decrease the delay. The multi-function switch provides a resistor multiplexed output to the Body Control Module (BCM) on a front wiper switch mux circuit, and the BCM responds by energizing the wiper ON/OFF relay in the Power Distribution Center (PDC) to operate the front wiper motor at the selected delay intervals.
- Intermittent Rear Wipe Mode - The control ring on the multi-function switch right (wiper) control stalk is rotated to the center detent to select the intermittent rear wiper mode. The multi-function switch provides a battery current output to the rear wiper motor on a rear wiper intermittent driver circuit to signal the rear wiper motor to operate in the intermittent wipe mode.
- Rear Washer Mode - The control ring on the multi-function switch right (wiper) control stalk is rotated to either the full forward (clockwise) or full rearward (counterclockwise) momentary positions to activate the washer pump in the rear washer mode. The washer pump will continue to operate in the rear washer mode until the control ring is released. The multi-function switch provides a ground output on a washer pump driver circuit, and battery current on a washer pump sense circuit to energize the washer pump in the rear washer mode.