Instrument Cluster

The instrument cluster for this vehicle is an electromechanical instrument cluster 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 below the cluster bezel. The instrument cluster for this vehicle also includes the hardware and software necessary to serve as the electronic body control module and is sometimes referred to as the cabin compartment node.

Besides analog gauges and indicators, the EMIC module incorporates a white digital vacuum fluorescent display unit for displaying odometer/trip odometer information, automatic transmission gear selector position (PRNDL), several warning or reminder indications and certain diagnostic information. A second optional VFD unit is available in some vehicles when they are equipped with the optional compass mini trip computer or the optional electronic vehicle information center. The information displayed in these VFD units is driven by a dot matrix display. The odometer, gear selector indicator VFD unit and the optional CMTC VFD unit are fixed segment display units; while the optional EVIC VFD unit is a large configuration display unit. The optional VFD units serve as the visual display for the compass, the outside temperature, the trip computer, the audio system settings as well as the user interface for the customer programmable features, numerous textual warning or reminder indicators and certain diagnostic information depending upon vehicle equipment.

The EMIC gauges and indicators are visible through dedicated openings in the cluster bezel and are protected by a clear plastic cluster lens. Integral latch formations on the lens secure it to the cluster hood and mask unit as well as the cluster housing. Just behind the cluster lens is the cluster hood and integral mask, which is constructed of molded black plastic. The 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 trims the outside perimeter of the cluster overlay. The hood and mask unit has integral latch features that secure it to the outer perimeter of the cluster housing. The cluster hood and mask also has four integral mounting tabs, one on each upper and lower corner of the housing. The cluster is secured to the instrument panel support structure by screws through these mounting tabs.

The rear of the cluster housing and the EMIC electronic circuitry are protected by a molded black plastic rear cover, which is also secured to the cluster housing by integral latch features. 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 dedicated take outs and connectors of the instrument panel wire harness.

Sandwiched between the rear cover and the lens and hood unit is the cluster housing. The molded white plastic cluster housing serves as the carrier for the cluster circuit board and circuitry, the cluster connector receptacles, the major and minor gauges, an LED for each cluster indicator, the VFD display units, an audible tone transducer, the cluster overlay and the gauge pointers. The cluster uses an electroluminescent lamp unit for general cluster illumination. A standard equipment molded black plastic odometer/trip odometer switch button extends from the face of the cluster housing through dedicated holes in the cluster mask and the cluster lens adjacent to the odometer VFD unit. Two additional switch buttons extend from the face of the cluster on either side of the CMTC display unit on vehicles that are so equipped.

The cluster overlay is a laminated plastic unit. The visible, outer surface of the overlay is marked with all of the gauge dial faces and graduations, but this layer is also translucent. 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, on vehicles so equipped, the LED general illumination lamps behind it to be visible through the outer layer of the overlay through predetermined stencil like cutouts. On vehicles with electroluminescent general illumination, the field of the gauges is illuminated and the gauge markings are silhouetted against the illuminated background. An opening in the overlay at the base of the gauge dial face on the right side of the cluster has a smoked clear lens through which the illuminated odometer VFD unit can be viewed. Likewise, on vehicles equipped with the optional CMTC or EVIC, an opening in the overlay at the base of the gauge dial face on the left side of the cluster has a smoked clear lens through which that illuminated VFD unit can be viewed.

Several versions of the EMIC module are offered on this vehicle. These versions accommodate not only the different car lines, but also all of the variations of optional equipment and regulatory requirements for the various markets in which the vehicle is offered. The microprocessor based EMIC utilizes integrated circuitry and information carried on the CAN data bus and the local interface network 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 and LIN data busses. Refer to COMMUNICATION DTC BASED DIAGNOSTICS (1 OF 2) & COMMUNICATION DTC BASED DIAGNOSTICS (2 OF 2) .

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 operating control of the accessory power delay relay.
• 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.
• Compass Mini Trip Computer Display Support - The EMIC provides support for the optional 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 switches and displays the appropriate information in the CMTC VFD unit.
• Electronic Vehicle Information Center Display Support - The EMIC provides support for each of the functions and features of the EVIC display. This includes support for the compass, thermometer and audio system mode, customer programmable features, textual warnings, TPM, trip computer.
• Enhanced Accident Response Support - The EMIC monitors inputs from the occupant restraint controller and the PCM to automatically turn ON the interior lighting after an airbag deployment event, 10 seconds after the vehicle speed is zero. The interior lighting remains illuminated until the key is removed from the ignition switch lock cylinder, at which time the interior lighting returns to normal operation and control. These enhanced accident response system features are each dependent upon a functional vehicle electrical system following the vehicle impact event.
• Exterior Lighting Switch Support - The EMIC monitors multiplexed hard wired inputs from the headlamp switch on the instrument panel as well as electronic headlamp dimmer switch status and turn signal switch status messages from the Steering Control Module integral to the multifunction switch on the left side of the steering column over the LIN data bus and transmits the appropriate electronic exterior lighting and turn signal request messages to the totally integrated power module over the CAN data bus to support the exterior lighting functions.
• Heated Seat Actuation Signal - Where used, the EMIC controls the heated seat system request input by transferring the request across the bus to the heated seat module.
• Horn Switch Support - On clusters equipped with a EVIC display, the EMIC receives electronic horn switch status messages from the SCM integral to the multifunction switch on the left side of the steering column over the LIN data bus and transmits the appropriate electronic horn request messages over the CAN data bus to support the horn function. On instrument clusters that are non EVIC equipped, the horn switch is hard wired to the EMIC and the EMIC will transmit the messages over the LIN data bus.
• Interior Lamp Load Shedding - The EMIC provides a battery saver feature which will automatically turn OFF all interior lamps if they remain ON after a timed interval of about ten minutes.
• Interior Lighting Control - The EMIC monitors electronic messages and hard wired inputs from the headlamp switch, the reading lamp switches, the sentry key remote entry module/wireless control module or Wireless Ignition Node and the TIPM to provide courtesy lamp control. This includes support for timed illuminated entry with theater style fade to OFF and courtesy illumination DEFEAT features.
• Local Interface Network Master Module - The EMIC is the master module for the LIN data bus. In this role it gathers information from the compass module, the Heated Seat Module, the instrument panel switch pod, the Steering Wheel Switch Module and the SCM, then either acts on that information directly or places electronic messages on the CAN data bus for use by other electronic modules.
• Panel Lamps Dimming Control - The EMIC monitors multiplexed hard wired inputs from the panel lamps dimmer switch thumb wheel in the headlamp switch, then provides both a hard wired 12 volt pulse width modulation output and electronic message outputs over the CAN data bus and the LIN data bus that synchronizes the dimming level of all panel lamps dimmer controlled lamps with that of the cluster general illumination lighting.
• Power Lock System Control - The EMIC monitors inputs from each of the door and liftgate modules, power lock switches and the SKREEM, also known as the WCM/WIN, then provides electronic lock and unlock messages back to the door and liftgate modules to control the power lock system. The EMIC also controls the automatic locking and RKE locking and unlocking features.
• Remote Radio Switch Interface - On clusters equipped with a EVIC display, the EMIC monitors electronic message inputs from the optional remote radio switches over the LIN data bus, then provides the appropriate electronic data bus messages to the radio to select the radio or optional hands free cellular system operating mode, volume control, preset station scan and station seek features. On instrument clusters that are not EVIC equipped, the remote radio switches are hard wired directly to the EMIC and the EMIC will transmit the messages over the LIN data bus.
• U Connect™ Hands-Free Voice Actuated Communication System Actuation Signal - Where used, the EMIC controls the U Connect™ system actuation signals.
• Vehicle Theft Security System Control - The EMIC monitors inputs across the bus to provide electronic horn and lighting request signals to the TIPM for the appropriate vehicle theft security system alarm output features.
• Wiper and Washer Switch Support - The EMIC monitors electronic wiper switch and washer switch status messages from the SCM integral to the multifunction switch on the left side of the steering column over the LIN data bus and transmits the appropriate electronic wiper and washer request messages to the TIPM over the CAN data bus to support the wiper and washer system functions, including the headlamps on with wipers programmable feature.

The EMIC houses either 3 or 4 analog gauges and has provisions for up to 25 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 configuration indicators will not be functional in a vehicle that does not have the equipment that an indicator supports.

Each indicator in the EMIC, except those located within a VFD unit, is illuminated by a dedicated LED that is soldered onto the EMIC electronic circuit board. Base cluster illumination is accomplished by several dimmable LED units, which illuminate each of the gauge dial faces for visibility when the exterior lighting is turned ON. These LED units are not available for service replacement and, if damaged or ineffective, the entire EMIC must be replaced. Premium cluster illumination is accomplished by a dimmable electroluminescent lamp, which illuminates each of the gauges for visibility when the exterior lighting is turned ON. The cluster lighting is white in color. The electroluminescent lamp units are not available for service replacement and, if damaged or ineffective, the entire EMIC must be replaced.

Hard wired circuitry connects the EMIC to the electrical system of the vehicle. These hard wired circuits are integral to several wire harnesses, which are routed throughout the vehicle and retained by many different methods. These circuits may be connected to each other, to the vehicle electrical system and to the EMIC through the use of a combination of soldered splices, splice block connectors, and many different types of wire harness terminal connectors and insulators. Refer to appropriate SYSTEM WIRING DIAGRAMS information.

The EMIC module for this vehicle is serviced only as a complete unit. The EMIC module cannot be adjusted or repaired. If a gauge, an LED unit, a VFD unit, the electronic circuit board, the circuit board hardware, the cluster overlay, the electroluminescent lamp or the cluster housing are damaged or ineffective, the entire EMIC module must be replaced. Some of the components for the instrument cluster used in this vehicle are serviced individually.

The EMIC in this vehicle 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. The following information deals primarily with the instrument cluster functions of this unit. Additional details of the electronic body control functions of this unit may be found within the service information for the system or component that the EMIC controls.

The EMIC is designed to allow the vehicle operator to monitor the conditions of many of the vehicle components and operating systems. The gauges and indicators in the EMIC provide valuable information about the various standard and optional powertrains, fuel and emissions systems, cooling systems, lighting systems, safety systems and many other convenience items. The EMIC is installed in the instrument panel so that all of these monitors can be easily viewed by the vehicle operator when driving, while still allowing relative ease of access for service.

The microprocessor based EMIC hardware and software uses various inputs to control the gauges and indicators visible on the face of the cluster. Some of these inputs are hard wired, but most are in the form of electronic messages that are transmitted by other electronic modules over the CAN data bus or the LIN data bus. The EMIC is the master node for the LIN data bus. Refer to COMMUNICATION DTC BASED DIAGNOSTICS (1 OF 2) & COMMUNICATION DTC BASED DIAGNOSTICS (2 OF 2) .

The EMIC microprocessor smooths the input data using algorithms to provide gauge readings that are accurate, stable and responsive to operating conditions. These algorithms are designed to provide gauge readings during normal operation that are consistent with customer expectations. However, when abnormal conditions exist such as high coolant temperature, the algorithm can drive the gauge pointer to an extreme position and the microprocessor can sound a chime through the on-board audible tone transducer to provide distinct visual and audible indications of a problem to the vehicle operator. The EMIC may also produce audible warnings for other electronic modules in the vehicle based upon electronic tone request messages received over the CAN or LIN data bus. Each audible warning is intended to provide the vehicle operator with an audible alert to supplement a visual indication.

The EMIC circuitry operates on battery current received through a fused B (+) fuse on a non switched fused B (+) circuit, and on battery current received through a fused ignition switch output (run-start) fuse on a fused ignition switch output (run-start) circuit. This arrangement allows the EMIC to provide some features regardless of the ignition switch position, while other features will operate only with the ignition switch in the ON or START positions. The EMIC circuitry is grounded through a ground circuit and take out of the instrument panel wire harness with an eyelet terminal connector that is secured by a ground screw to a ground location on the instrument panel structural support.

The EMIC also has a self-diagnostic actuator test capability, which will test each of the CAN or LIN bus message controlled functions of the cluster by lighting the appropriate indicators, positioning the gauge needles at several predetermined calibration points across the gauge faces, and illuminating all segments of the VFD units. Refer to NON-DTC BASED DIAGNOSTICS (2 OF 2) .

Gauges 

All gauges receive battery current through the EMIC circuitry only when the ignition switch is in the ON or START positions. With the ignition switch in the OFF position battery current is not supplied to any gauges, and the EMIC circuitry is programmed to move all of the gauge needles back to the low end of their respective scales. Therefore, the gauges do not accurately indicate any vehicle condition unless the ignition switch is in the ON or START positions.

Each of the EMIC gauges contains an electronically controlled stepper motor unit. The EMIC circuitry completely controls the activation and deactivation of these stepper motors to position each gauge needle in the appropriate position based upon cluster programming and electronic messages received over the CAN or LIN data bus.

The gauges are diagnosed using the self diagnostic CCN actuator test. Proper testing of the CAN or LIN data bus and the electronic data bus message inputs to the EMIC that control each gauge requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information. Specific operation details for each gauge may be found elsewhere in this service information.

Vacuum Fluorescent Displays 

The VFD units are soldered to the EMIC electronic circuit board. Both the standard odometer and gear selector indicator VFD unit and the optional CMTC VFD unit are fixed segment dot matrix displays. The optional EVIC VFD unit is a configuration dot matrix display. With the ignition switch in the OFF or ACCESSORY positions, all VFD displays are deactivated. The total odometer information is displayed when the driver door is opened (rental car mode) and is deactivated when the driver door is closed or after five minutes, whichever occurs first. Otherwise, all VFD units are active when the ignition switch is in the ON or START positions, and inactive when the ignition switch is in the OFF or ACCESSORY positions.

The illumination intensity of the VFD units is controlled by the EMIC circuitry based upon electronic dimming level messages received over the CAN data Bus indicating the exterior lighting is turned ON and the dimming level selected using the panel dimmer function of the thumb wheel on the headlamp switch. The illumination intensity of the EMIC VFD units is synchronized with that of other display units in the vehicle by sending the same electronic dimming level message inputs to all electronic modules in the vehicle over the CAN or LIN data bus.

The odometer VFD unit has several display capabilities including odometer, trip odometer A and B, the cruise indicator, gear selector indicator, several textual warning or reminder indications, and various diagnostic information when certain fault conditions exist. The optional CMTC VFD unit displays compass, temperature, average fuel economy, distance to empty, elapsed time and cycles the optional park assist feature ON or OFF. The display options for these VFD units are selected using switches on the EMIC circuit board that are actuated using push buttons adjacent to the displays. The optional EVIC VFD unit displays several textual warning or reminder indications, compass, temperature, average fuel economy, distance to empty, elapsed time, audio settings and provides a customer programmable features interface. The EVIC display options are selected using steering wheel-mounted switches.

Actuating the odometer/trip odometer push button momentarily with the ignition switch in the ON position will toggle the odometer VFD between the odometer and trip odometer modes. Depressing the odometer/trip odometer push button for about two seconds while the VFD is in the trip odometer mode will reset the trip odometer value to zero. Holding the odometer/trip odometer push button depressed while turning the ignition switch from the OFF position to the ON position will initiate the CCN self-diagnostic actuator test. Refer to the instrument cluster diagnosis and testing service information for additional details on this cluster function. The EMIC microprocessor remembers which odometer display mode is active when the ignition switch is turned to the OFF position, and returns the display to that mode when the ignition switch is turned ON again.

Actuating the right CMTC push button momentarily with the ignition switch in the ON position will toggle the CMTC VFD between the various display functions, and actuating the left CMTC push button toggles the display between U.S. and metric units. The EMIC microprocessor remembers which display mode is active when the ignition switch is turned to the OFF position, and returns the display to that mode when the ignition switch is turned ON again.

All EMIC VFD units are diagnosed using the self diagnostic CCN actuator test. Refer to NON-DTC BASED DIAGNOSTICS (2 OF 2) . Proper testing of the CAN or LIN data bus message inputs to the EMIC that control some of the VFD functions requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information. Specific operation details for the odometer, the trip odometer, the gear selector indicator, the CMTC, the EVIC and the various warning and reminder indicator functions of the VFD units may be found elsewhere in this service information.

Indicators 

Indicators are located in various positions within the EMIC and are all connected to the EMIC electronic circuit board. Some indicators operate based upon hard wired inputs to the EMIC, but most are controlled by CAN or LIN data bus messages from other electronic modules in the vehicle. Some are controlled by a combination of hard wired inputs, electronic messaging and EMIC programming. If the EMIC loses CAN data bus communication, the EMIC circuitry will automatically turn ON the MIL until CAN data bus communication is restored. If the EMIC loses CAN data bus communication with the TIPM, all of the modules that are supported by the CAN C data bus will illuminate the appropriate cluster tell tail warnings.

The various EMIC indicators are controlled by different strategies; some receive fused ignition switch output from the EMIC circuitry and have a switched ground, while others are grounded through the EMIC circuitry and have a switched battery feed. However, all indicators are completely controlled by the EMIC microprocessor based upon various hard wired and electronic message inputs. The cruise indicator located within the odometer VFD unit is dimmable. All other indicators are illuminated at a fixed intensity, which is not affected by the selected illumination intensity of the EMIC general illumination lighting. The illumination intensity of the dimmable indicator is synchronized with that of the general illumination lighting.

In addition, certain indicators in this instrument cluster are automatically or self-configured. This feature allows the configuration indicators to be enabled by the EMIC circuitry for compatibility with certain optional equipment. These indicators are enabled or disabled by an electronic configuration message sent to the EMIC by the TIPM. The TIPM defaults for the ABS indicator and airbag indicator are enabled, and these configuration settings must be programmatically disabled in the TIPM using a diagnostic scan tool for vehicles that do not have this equipment. The automatically or self-configured indicators remain latent in each EMIC at all times and will be active only when the EMIC receives the appropriate CAN or LIN bus message inputs for that optional system or equipment.

The hard wired indicator inputs may be diagnosed using conventional diagnostic tools and procedures. However, the EMIC circuitry and electronic CAN or LIN data bus message controlled indicators are diagnosed using the self diagnostic CCN actuator test. Refer to NON-DTC BASED DIAGNOSTICS (2 OF 2) . Proper testing of the CAN or LIN data bus and the electronic data bus message inputs to the EMIC that control each indicator requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

Cluster Illumination 

The base EMIC has several LED units that provide cluster back lighting whenever the exterior lighting is turned ON. The illumination intensity of these LED units is adjusted when the panel lamps dimmer function of the thumb wheel on the headlamp switch is rotated to one of six available minor detente positions. The EMIC monitors a hard wired multiplexed input received from the headlamp switch on the instrument panel to determine the selected lighting level. In response to that input, the EMIC electronic circuitry converts a fused 12 volt input it receives on a hard wired panel lamps dimmer switch signal circuit into a 12 volt PWM output.

The EMIC uses this PWM output to control the illumination intensity of the cluster general illumination lighting and the VFD units on the EMIC circuit board, then provides a synchronized PWM output on various hard wired fused panel lamps dimmer switch signal circuits to control and synchronize the illumination intensity of other incandescent illumination lamps in the vehicle. The EMIC also transmits electronic dimming level messages over the CAN and LIN data bus to other electronic modules in the vehicle to control and synchronize the illumination intensity of their display units to that of the EMIC displays.

The hard wired panel lamps dimmer outputs from the EMIC may be diagnosed using conventional diagnostic tools and procedures. However, proper testing of the PWM processing of the EMIC and the electronic dimming level messages received by the EMIC over the LIN data bus requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.