Part 1 of 2
The instrument cluster (1) for this model is an Electro-Mechanical Instrument Cluster (EMIC) that is located in the instrument panel above the steering column opening, directly in front of the driver. The remainder of the EMIC, including the mounts and the electrical connections, are concealed within the instrument panel behind the cluster bezel (2). Besides analog gauges and indicators, the EMIC module incorporates two blue-green digital Vacuum Fluorescent Display (VFD) units for displaying odometer/trip odometer information, engine hours, automatic transmission gear selector position (PRNDL), several warning or reminder indications and certain diagnostic information. The instrument cluster for this model also includes the hardware and software necessary to serve as the electronic body control module and is sometimes referred to as the Cab Compartment Node or CCN.
The EMIC gauges and indicators are visible through a dedicated opening in the cluster bezel on the instrument panel and are protected by a clear plastic cluster lens that is integral to a cluster lens, hood and mask unit (3). Just behind the cluster lens is the cluster hood and an integral cluster mask, which are constructed of molded black plastic. Two different masks are used, one with silver rings and one with chrome rings around the gauge openings. The cluster hood serves as a visor and shields the face of the cluster from ambient light and reflections to reduce glare, while the cluster mask serves to separate and define the individual gauges and indicators of the EMIC. A black plastic odometer/trip odometer switch button protrudes through dedicated holes in the cluster mask and the cluster lens, located near the lower edge of the cluster just to the left of the fuel gauge. The molded plastic EMIC lens, hood and mask unit has four integral mounting tabs, two each on the upper and lower edges of the unit. These mounting tabs are used to secure the EMIC to the molded plastic instrument panel cluster carrier with four screws.
The rear of the cluster housing and the EMIC electronic circuitry are protected by a molded plastic rear cover (1), which is secured to the cluster housing with fourteen screws, while eight screws installed around the outside perimeter of the rear cover secure it to the cluster lens, hood and mask unit. The rear cover
includes clearance holes for the cluster connector receptacles. The connector receptacles on the back of the cluster electronic circuit board connect the EMIC to the vehicle electrical system through three take outs with connectors from the instrument panel wire harness.
Sandwiched between the rear cover and the lens, hood and mask unit is the cluster housing (2). The molded plastic cluster housing serves as the carrier for the cluster circuit board and circuitry, the cluster connector receptacles, the RKE interface connector, the gauges, a Light Emitting Diode (LED) for each cluster indicator, two VFD units, an audible tone transducer, an electro-luminescent lamp for general cluster illumination, the cluster overlay, the gauge pointers, the odometer/trip odometer switch and the switch button.
The cluster overlay is a laminated plastic unit. The dark, visible, outer surface of the overlay is marked with all of the gauge dial faces and graduations, but this layer is also translucent. The darkness of this outer layer prevents the cluster from appearing cluttered or busy by concealing the cluster indicators that are not illuminated, while the translucence of this layer allows those indicators and icons that are illuminated to be readily visible. The underlying layer of the overlay is opaque and allows light from the LED for each of the various indicators and an electro-luminescent lamp behind it to be visible through the outer layer of the overlay only through predetermined stencil-like cutouts. A rectangular opening in the overlay at the base of both the minor gauge set and the tachometer dial faces has a smoked clear lens through which the illuminated VFD units can be viewed.
Several versions of the EMIC module are offered on this model. These versions accommodate all of the variations of optional equipment and regulatory requirements for the various markets in which the vehicle will be offered. The microprocessor-based EMIC utilizes integrated circuitry and information carried on the Controller Area Network (CAN) data bus along with several hard wired analog and multiplexed inputs to monitor sensors and switches throughout the vehicle. In response to those inputs, the internal circuitry and programming of the EMIC allow it to control and integrate many electronic functions and features of the vehicle through both hard wired outputs and the transmission of electronic message outputs to other electronic modules in the vehicle over the CAN data bus.
Besides typical instrument cluster gauge and indicator support, the electronic functions and features that the EMIC supports or controls include the following:
- Accessory Power Delay Relay Control - The EMIC provides timing and control for the accessory power delay relay based upon inputs from both the ignition switch and the door ajar switches.
- Audible Warnings - The EMIC electronic circuit board is equipped with an audible tone transducer and programming that allows it to provide various audible alerts to the vehicle operator, including chime tones and beep tones. An electromechanical relay is also soldered onto the circuit board to produce audible clicks that emulate the sound of a conventional turn signal or hazard warning flasher.
- Automatic Headlamps Control - On models equipped with optional automatic headlamps, the EMIC monitors inputs from both the headlamp switch and a sun load sensor located on the top of the instrument panel to provide automatic headlamps.
- Brake Lamp Control - The EMIC provides electronic brake lamp request messages to the Front Control Module (FCM) located on the Integrated Power Module (IPM) for brake lamp control, excluding control of the Center High Mounted Stop Lamp (CHMSL), which remains controlled by a direct hard wired output of the brake lamp switch.
- Brake Transmission Shift Interlock Control - The EMIC monitors inputs from the brake lamp switch, ignition switch, and the Transmission Range Sensor (TRS), then controls a high-side driver output to operate the Brake Transmission Shift Interlock (BTSI) solenoid that locks and unlocks the automatic transmission gearshift selector lever on the steering column.
- Compass Mini Trip Computer Support - The EMIC provides support for the optional Compass Mini Trip Computer (CMTC) by calculating average fuel economy, distance to empty and outside temperature values and storing trip odometer and elapsed ignition on time data. The EMIC receives data and reset requests from the CMTC and transmits the appropriate information for the CMTC to display using electronic messaging.
- Electronic Transfer Case Interface - On vehicles equipped with an electronic four-wheel drive transfer case, the EMIC monitors a hard wired multiplex input from the transfer case mode switch and then provides the appropriate electronic data bus messages to the Front Control Module (FCM) located on the Integrated Power Module (IPM) for transfer case control. After the transfer case shift is completed, the FCM provides an electronic message to the EMIC and the EMIC responds by activating the appropriate 4WD indicators within the cluster or in the transfer case switch.
- Enhanced Accident Response Support - The EMIC monitors an input from the Occupant Restraint Controller (ORC) and, following an airbag deployment, will immediately disable the power lock output, unlock all doors by activating the power unlock output, then enables the power lock output if the power lock switch input remains inactive for two seconds. The EMIC also monitors an input from the Powertrain Control Module (PCM) to automatically turn on the interior lighting after an airbag deployment event, ten seconds after the vehicle speed is zero. The interior lighting remains illuminated until the ignition switch is turned to the Off position, at which time the interior lighting returns to normal operation and control. These Enhanced Accident Response System (EARS) features are each dependent upon a functional vehicle electrical system following the vehicle impact event.
- Exterior Lamp Load Shedding - The EMIC provides a battery saver feature which will automatically turn off all exterior lamps that remain on with the ignition switch in the Off position after a timed interval of about five minutes.
- Exterior Lighting Control - The EMIC provides electronic head lamp and/or park lamp request messages to the Front Control Module (FCM) located on the Integrated Power Module (IPM) for the appropriate exterior lamp control of standard head and park lamps, as well as optional front fog lamps. This includes support for headlamp beam selection and the optical horn feature, also known as flash-to-pass.
- Exterior Lighting Fail-safe - In the absence of a headlamp switch input, the EMIC will turn on the cluster illumination lamps and provide electronic headlamp low beam and park lamp request messages to the Front Control Module (FCM) located on the Integrated Power Module (IPM) for default exterior lamp operation. The FCM will also provide default park lamp and headlamp low beam operation and the EMIC will turn on the cluster general illumination lighting if there is a failure of the electronic data bus communication between the EMIC and the FCM.
- Fuel Level Data Support - The EMIC provides a current source for and receives a hard wired analog input from the fuel level sending unit located on the fuel pump module in the fuel tank. The EMIC uses this input to calculate the proper fuel gauge needle position and low fuel indicator operation. Based upon this input, the EMIC also calculates fuel level, average fuel economy and distance to empty data, then uses electronic messaging to transmit this data over the CAN data bus for use by other electronic modules in the vehicle.
- Heated Seat Control - The EMIC monitors inputs from the ignition switch and electronic engine speed messages from the Powertrain Control Module (PCM) to control a high side driver output to the heated seat switch Light Emitting Diode (LED) indicators. This input allows the heated seat switches to wake up the heated seat module if the switch is actuated. The EMIC will de-energize the heated seat switch LED indicators, which deactivates the heated seat system, if the ignition switch is turned to any position except On or Start, or if the engine speed message indicates zero.
- Horn Control - The EMIC monitors an input from the horn switch and provides electronic horn request messages to the Front Control Module (FCM) located on the Integrated Power Module (IPM) for horn relay control. The EMIC also controls horn relay operation in this manner to provide the horn features of the optional Remote Keyless Entry (RKE) or Vehicle Theft Security System (VTSS).
- Interior Lamp Load Shedding - The EMIC provides a battery saver feature which will automatically turn off all interior lamps that remain on after a timed interval of about fifteen minutes.
- Interior Lighting Control - The EMIC monitors inputs from the interior lighting switch, the door ajar switches, the reading lamp switches, and the Sentry Key Remote Entry Module (SKREEM) to provide courtesy lamp control. This includes support for timed illuminated entry with theater-style fade-to-off and courtesy illumination defeat features.
- Panel Lamps Dimming Control - The EMIC monitors hard wired multiplexed inputs from the headlamp switch on the instrument panel, then provides a hard wired 12-volt Pulse-Width Modulated (PWM) output that synchronizes the dimming level of all panel lamps dimmer controlled lamps with that of the cluster illumination lighting.
- Power Locks - The EMIC monitors inputs from the power lock switches and the Sentry Key REmote Entry Module (SKREEM) to provide control of the power lock motors through high side driver outputs to the motors. This includes support for rolling door locks (also known as automatic door locks), automatic door unlock, briefcase lock mode, door lock inhibit mode, and central locking (with the optional Vehicle Theft Security System only).
- Remote Keyless Entry - The EMIC supports the standard Remote Keyless Entry (RKE) system features, including support for the RKE Lock, Unlock (with optional driver-door-only unlock, and unlock-all-doors), Panic, audible chirp, optical chirp, illuminated entry modes, an RKE programming mode, as well as optional Vehicle Theft Security System (VTSS) arming (when the proper VTSS arming conditions are met) and disarming.
- Remote Radio Switch Interface - The EMIC monitors inputs from the optional remote radio switches and then provides the appropriate electronic data bus messages to the radio to select the radio operating mode, volume control, preset station scan and station seek features.
- Turn Signal & Hazard Warning Lamp Control - The EMIC monitors hard wired multiplexed inputs from the multi-function switch on the steering column, then provides electronic turn and hazard lamp request messages to the Front Control Module (FCM) located on the Integrated Power Module (IPM) for turn and hazard lamp control. The EMIC also provides an audible click at one of two rates to emulate normal and bulb out turn or hazard flasher operation based upon electronic lamp outage messages from the FCM, and provides an audible turn signal on chime warning if a turn is signalled continuously for more than about 1.6 kilometers (one mile) and the vehicle speed remains greater than about twenty-four kilometers-per-hour (fifteen miles-per-hour).
- Vacuum Fluorescent Display Synchronization - The EMIC monitors hard wired multiplexed inputs from the headlamp switch on the instrument panel, then transmits electronic panel lamp dimming level messages which allows all other electronic modules on the CAN data bus with Vacuum Fluorescent Display (VFD) units to coordinate their illumination intensity with that of the EMIC VFD units. This includes a parade mode (also known as funeral mode) that allows all VFD units in the vehicle to be illuminated at full (daytime) intensity while driving during daylight hours with the exterior lamps turned On.
- Vehicle Theft Security System Control - The EMIC monitors inputs from the door ajar switches, the lift-gate ajar switch, the ignition switch, and the Sentry Key REmote Entry Module (SKREEM), then provides electronic horn and lighting request messages to the Front Control Module (FCM) located on the Integrated Power Module (IPM) for the appropriate VTSS alarm output features.
- Wiper/Washer System Control - The EMIC monitors both hard wired multiplexed inputs from the front wiper and washer switches in the multi-function switch on the steering column and electronic messages from the rear wiper and washer switches in the heater and air conditioner control on the instrument panel. The EMIC then provides electronic wiper and/or washer request messages to the Front Control Module (FCM) located on the Integrated Power Module (IPM) for the appropriate front or rear wiper and washer system features.
The EMIC houses four analog gauges, two VFD units and has provisions for up to twenty-five indicators. Some of the EMIC indicators are automatically configured when the EMIC is connected to the vehicle electrical system for compatibility with certain optional equipment or equipment required for regulatory purposes in certain markets. While each EMIC may have provisions for indicators to support every available option, the configurable indicators will not be functional in a vehicle that does not have the equipment that an indicator supports.