Instrument Cluster Description

Instrument Cluster:

The instrument cluster for this model is an Electro Mechanical Instrument Cluster (EMIC) that is located above the steering column opening in the instrument panel, 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 and beneath the instrument panel top cover for the cluster. The instrument cluster includes analog gauges, meters, indicators, and acoustic signal transmitters.

The EMIC module also incorporates a multi-function indicator that consists of a digital Liquid Crystal Display (LCD) unit for displaying odometer/trip odometer information, an electronic digital clock, engine oil level information, automatic transmission gear selector position (PRNDL), and certain diagnostic information. The multi-function indicator also has four push button switches, which provide the vehicle operator with an interface to adjust certain inputs to the instrument cluster and to select from multiple display options. If the vehicle is equipped with the appropriate options, the multi-function indicator also provides an outside ambient temperature indicator display and an Active Service System (ASSYST) engine oil maintenance indicator to display engine oil level and maintenance reminders.

Instrument Cluster Components:

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 secured by eight integral latches to the molded black plastic cluster hood. Four, black plastic multi-function indicator switch push buttons protrude through dedicated holes in a rectangular black plastic switch bezel that is integral to the cluster lens and located near the lower edge of the cluster directly below the multifunction indicator LCD unit. The cluster hood serves as a visor and shields the face of the cluster from ambient light and reflections to reduce glare. The cluster hood has eight integral latches that engage eight integral latch tabs on the cluster rear cover, sandwiching the cluster housing unit between the hood and the rear cover. The cluster hood also has two integral pivot loops molded into its underside that engage two pairs of molded pivot hooks that are integral to the top of the instrument panel base structure. These pivots allow the cluster to be rolled rearward to ease service access to the wire harness connectors at the back of the cluster.

The rear of the cluster housing and the EMIC electronic circuitry are protected by the molded plastic rear cover. A mounting ear at each upper corner of the rear cover are used to secure the EMIC to the molded plastic instrument panel base unit with two screws. The rear cover includes clearance holes for the two cluster connector receptacles on the cluster electronic circuit board. The connector receptacles on the back of the cluster electronic circuit board connect the EMIC to the vehicle electrical system through two take outs with connectors from the vehicle wire harness. The EMIC rear cover includes a molded mounting tab and a latch feature that secures the RKE/immobilizer module to the back of the cluster. The RKE/immobilizer module is connected to the vehicle electrical system through a separate take out and connector of the vehicle wire harness.

Located between the rear cover and the cluster hood is the cluster housing. The molded plastic cluster housing serves as the carrier for the cluster electronic circuit board and circuitry, the cluster connector receptacles, the gauges, a Light Emitting Diode (LED) for each cluster indicator and general illumination lamp, the multi-function indicator LCD unit, electronic tone generators, the cluster overlay, the gauge pointers, the multi-function indicator switches and the four switch push buttons.

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 illumination lamps behind it to be visible through the outer layer of the overlay only through predetermined cutouts. A rectangular opening in the overlay at the base of the speedometer provides a window through which the illuminated multi-function indicator LCD unit 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, Electrically Erasable Programmable Read Only Memory (EEPROM) type memory storage, information carried on the Controller Area Network (CAN) data bus, along with several hard wired analog and multiplexed inputs to monitor systems, sensors and switches throughout the vehicle.

In response to those inputs, the hardware and software 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:
- Active Service System - In vehicles equipped with the Active Service System (ASSYST) engine oil maintenance indicator option, the EMIC electronic circuit board includes a second dedicated microprocessor. This second microprocessor evaluates various data including time, mileage, and driving conditions to calculate the required engine oil service intervals, and provides both visual and audible alerts to the vehicle operator when certain engine oil maintenance services are required.
- Audible Warnings - The EMIC electronic circuit board is equipped with an audible tone generator and programming that allows it to provide various audible alerts to the vehicle operator, including buzzing and chime tones. An audible contactless electronic relay is also soldered onto the circuit board to produce audible clicks that is synchronized with turn signal indicator flashing to emulate the sounds of a conventional turn signal or hazard warning flasher. These audible clicks can occur at one of two rates to emulate both normal and bulb-out turn or hazard flasher operation.
- Panel Lamps Dimming Control - The EMIC 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 general illumination lamps and multifunction indicator.

Gauges & Indicators:

The EMIC houses four analog gauges and has provisions for up to nineteen indicators. The EMIC includes the following analog gauges:
- Coolant Temperature Gauge
- Fuel Gauge
- Speedometer
- Tachometer
The EMIC includes provisions for the following indicators:
- Airbag (SRS) Indicator
- Antilock Brake System (ABS) Indicator
- Brake Indicator
- Brake Wear Indicator
- Charging Indicator
- Clogged Fuel Filter Indicator
- Constant Engine Speed (ADR) Indicator
- Coolant Low Indicator
- Electronic Stability Program (ESP) Indicator
- High Beam Indicator
- Low Fuel Indicator
- Malfunction Indicator Lamp (MIL)
- Multi-Function Indicator (LCD)
- Park Brake Indicator
- Seatbelt Indicator
- Traction Control (ASR) Indicator
- Traction Control (ASR) Malfunction Indicator
- Turn Signal (Right and Left) Indicators
- Washer Fluid Indicator
- Wait-To-Start Indicator
- Water-In-Fuel Indicator

Except for the indications provided within the multi-function indicator LCD unit, each indicator in the EMIC is illuminated by a dedicated LED that is soldered onto the EMIC electronic circuit board. Cluster illumination is accomplished by dimmable LED back lighting, which illuminates the gauges for visibility when the exterior lighting is turned on. The cluster general illumination LED units are also soldered onto the EMIC electronic circuit board. The LED units are not available for service replacement and, if damaged or faulty, 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 the vehicle 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 the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.

The EMIC modules for this model are serviced only as complete units. The EMIC module cannot be adjusted or repaired. If a gauge, an LED indicator, the multi-function indicator LCD unit, an electronic tone generator, the electronic circuit board, the circuit board hardware, the cluster overlay, the cluster housing, the cluster hood, the cluster lens, or the cluster rear cover are damaged or faulty, the entire EMIC module must be replaced.

The ElectroMechanical Instrument Cluster (EMIC) is designed to allow the vehicle operator to monitor the conditions of many of the vehicle components and operating systems. The gauges, meters and indicators in the EMIC provide valuable information about the powertrain, fuel and emissions systems, cooling system, 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 many are in the form of electronic messages that are transmitted by other electronic modules over the Controller Area Network (CAN) data bus network.

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 generator to provide distinct visual and audible indications of a problem to the vehicle operator. The instrument cluster circuitry also provides audible turn signal and hazard warning support by emulating the "ticking" sound associated with a conventional electro-mechanical flasher using a contactless relay. The relay will also provide an indication of a turn signal failure by sounding at double the usual frequency. Each audible warning is provided to the vehicle operator to supplement a visual indication.

The EMIC circuitry operates on battery current received through a non-switched fused B(+) circuit, and on a fused ignition switch output circuit. The EMIC circuitry is grounded through a ground circuit and take out of the frame wire harness with an eyelet terminal connector that is secured to a stud by a nut at a ground location on the dash panel just forward of the instrument cluster. Separate switched ground inputs from the key-in ignition switch and the front door jamb switches provide wake-up signals to the EMIC circuitry. 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 position.

Proper diagnosis and testing of the EMIC, the CAN data bus, the data bus electronic message inputs to and outputs from the EMIC, as well as the retrieval or erasure of a Diagnostic Trouble Code (DTC) requires the use of a DRBIII(R) scan tool. Refer to the appropriate diagnostic information. See the owner's manual in the vehicle glove box for more information on the features, use and operation of the EMIC.

GAUGES
All gauges receive battery current through the EMIC circuitry only when the instrument cluster detects the ignition switch is in the On position. 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 position.

All of the EMIC gauges are air core magnetic units. Two fixed electromagnetic coils are located within each gauge. These coils are wrapped at right angles to each other around a movable permanent magnet. The movable magnet is suspended within the coils on one end of a pivot shaft, while the gauge needle is attached to the other end of the shaft. One of the coils has a fixed current flowing through it to maintain a constant magnetic field strength. Current flow through the second coil changes, which causes changes in its magnetic field strength. The current flowing through the second coil is changed by the EMIC circuitry in response to messages received over the CAN data bus. The gauge needle moves as the movable permanent magnet aligns itself to the changing magnetic fields created around it by the electromagnets.

Proper diagnosis and testing of the gauges, the CAN data bus and the electronic data bus message inputs to the EMIC that control each gauge require the use of a DRBIII(R) scan tool. Refer to the appropriate diagnostic information. Specific operation details for each gauge 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. The ambient temperature indicator (optional), brake indicator, brake wear indicator, charging indicator, coolant low indicator, high beam indicator, low fuel indicator, park brake indicator, seatbelt indicator, turn signal indicators, and washer fluid indicator operate based upon hard wired inputs to the EMIC. The airbag (SRS) indicator is normally controlled by a hard wired input from the Airbag Control Module (ACM); however, if the EMIC sees an abnormal or no input from the ACM, it will automatically turn the airbag indicator On until the hard wired input from the ACM has been restored. The Malfunction Indicator Lamp (MIL) is normally controlled by CAN data bus messages from the Engine Control Module (ECM); however, if the EMIC loses CAN data bus communication, the EMIC circuitry will automatically turn the MIL on until CAN data bus communication is restored. The EMIC uses CAN data bus messages from the ECM, the ACM, and the Controller Antilock Brake to control all of the remaining indicators.

The various EMIC indicators are controlled by different strategies; some receive battery feed 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. Except for the indications provided by the multi-function indicator Liquid Crystal Display (LCD) unit, all indicators are illuminated at a fixed intensity, which is not affected by the selected illumination intensity of the EMIC general illumination lamps.

The hard wired indicator inputs may be diagnosed using conventional diagnostic methods. However, proper testing of the EMIC circuitry and the CAN bus message controlled indicators requires the use of a DRBIII(R) scan tool. Refer to the appropriate diagnostic information. Specific details of the operation for each indicator may be found elsewhere in this service information.

CLUSTER ILLUMINATION
The EMIC has several general illumination lamps that are illuminated when the exterior lighting is turned on with the multi-function switch. The illumination intensity of these lamps is adjusted by a dimming level input received from the multi-function indicator "+" (plus) and "-" (minus) switch push buttons that extend through the lower edge of the cluster lens below the right end of the multi-function indicator. When the exterior lighting is turned Off, the display is illuminated at maximum brightness. When the exterior lighting is turned On and the transmission gear selector is in the Park position, depressing the plus switch push button brightens the display lighting, and depressing the minus switch push button dims the display lighting. The EMIC also provides a Pulse-Width Modulated (PWM) panel lamps dimmer output that can be used to synchronize the illumination lighting levels of external illumination lamps (up to about 23 to 30 watts) with that of the EMIC.

The hard wired multi-function switch input and the EMIC panel lamps dimmer output may be diagnosed using conventional diagnostic methods. However, proper testing of the PWM control of the EMIC and the electronic dimming level inputs from the multi-function indicator push buttons requires the use of a DRBIII(R) scan tool. Refer to the appropriate diagnostic information.

INPUT AND OUTPUT CIRCUITS

HARD WIRED INPUTS
The hard wired inputs to the EMIC include the following:

NOTE: Final approved circuit names were not yet available at the time this information was compiled.
- Airbag Indicator Driver
- Ambient Temperature Sensor Signal (Optional)
- Brake Wear Indicator Sense
- Charging Indicator Driver
- Coolant Level Switch Sense
- Front Door Jamb Switch Sense
- Fuel Level Sensor Signal
- Fused B(+)
- Fused Ignition Switch Output
- High Beam Indicator Driver
- Key-In Ignition Switch Sense
- Left Turn Signal
- Park Brake Switch Sense
- Right Turn Signal
- Seat Belt Switch Sense
- Washer Fluid Switch Sense (Optional)
Refer to the appropriate wiring information for additional details.

HARD WIRED OUTPUTS
The hard wired outputs of the EMIC include the following:
- Engine Running Relay Control
- Panel Lamps Driver
Refer to the appropriate wiring information for additional details.

GROUNDS
The EMIC receives and supplies a ground path to several switches and sensors through the following hard wired circuits:
- Ambient Temperature Sensor Return (Optional)
- Fuel Level Sensor Return
- Ground
Refer to the appropriate wiring information for additional details.

COMMUNICATION
The EMIC has provisions for the following communication circuits:
- CAN Data Bus - High
- CAN Data Bus - Low
- Diagnostic Serial Communication Interface (SCI) Data Bus Line
Refer to the appropriate wiring information for additional details.