Instrument Cluster: Description

The instrument cluster for this model is an ElectroMechanical 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. Besides analog gauges and indicators, the EMIC module incorporates a blue-green digital Vacuum Fluorescent Display (VFD) unit for displaying odometer/trip odometer information and certain diagnostic information. The instrument cluster for this model also includes the hardware and software necessary to serve as an electronic body control module.

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. Eight integral latch formations around the outer perimeter of the lens secure the lens unit to the cluster hood and the cluster housing. On the lower edge of the cluster lens just right of center, a small molded rubber boot covers the odometer/trip odometer switch button and seals a dedicated pocketed hole in the lens through which the switch button protrudes. Just behind the cluster lens is the cluster hood and an integral cluster mask, which are constructed of molded black plastic. 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 trims the outside perimeter of the cluster overlay. The cluster hood and mask unit is secured to the cluster housing with five integral latch formations around its perimeter.

The rear of the cluster housing and the EMIC electronic circuitry are protected by a molded plastic rear cover, which is secured to the cluster housing with two screws, eight integral latch formations around its perimeter, and a single latch that is integral to the cluster housing. The rear cover includes clearance holes for service access to each of the five general illumination lighting and the one high beam indicator incandescent bulb and bulb holder units installed on the cluster circuit board, and for the two color-coded cluster connector receptacles. 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 color-coded connectors from the instrument panel wire harness.

Sandwiched between the rear cover and the lens, hood and mask unit is the cluster housing. The molded plastic cluster housing serves as the carrier for the cluster circuit board and circuitry, the cluster connector receptacles, the gauges, a Light Emitting Diode (LED) for each cluster indicator, the VFD unit, an audible tone generator, the cluster overlay, the gauge pointers, the odometer/trip odometer switch and the switch button. The molded plastic EMIC housing has four integral mounting tabs, two on the lower outboard edges of the housing and one on each side. A screw through each of these four mounting tabs secures the EMIC to the instrument panel structural support.

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 or incandescent lamp for each of the various indicators and the incandescent illumination lamps behind it to be visible through the outer layer of the overlay only through predetermined stencil-like cutouts. A rectangular opening near the base of the overlay between the speedometer and tachometer dial faces has a smoked clear lens through which the illuminated VFD 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 and information carried on the Programmable Communications Interface (PCI) data bus network 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 PCI data bus. See ELECTRONIC CONTROL MODULES article.

Besides typical instrument cluster gauge and indicator support, the electronic functions and features that the EMIC supports or controls include the following:

• Audible Warnings  - The EMIC electronic circuit board is equipped with an audible tone generator and programming that allows it to provide various audible chime tone alerts to the vehicle operator. See CHIME/BUZZER article.
• Audio System Cabin Equalization  - The EMIC stores the cabin equalization curves for various optional speaker system architectures for use by the radio. The EMIC provides this information when requested by the radio over the PCI data bus. Changing the cabin equalization settings of the EMIC requires the use of a DRBIII(R) scan tool. Refer to the appropriate diagnostic information.
• Axle Locker Control  - The EMIC provides the logic that controls the operation of the rear and front axle locker feature found on models equipped with the optional off-road package.
• Electronic Pinion Factor  - The EMIC stores the tire size, axle ratio, and transfer case type information for use in calibrating the proper vehicle speed and distance values for display by the speedometer and odometer, as well as for use by other electronic modules in the vehicle. The EMIC provides this information when requested by other modules over the PCI data bus. Changing the electronic pinion factor settings of the EMIC requires the use of a DRBIII(R) scan tool. Refer to the appropriate diagnostic information.
• 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 twenty minutes.
• Interior Lighting Control  - The EMIC monitors inputs from the interior lighting switch and the door ajar switches to provide courtesy lamp control. This includes support for a timed illuminated entry with a theater-style fade-to-off feature.
• 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 illumination lamps. This includes providing features such as VFD unit illumination when a door is ajar (rental car mode), radio illumination control, a parade mode, and one step dimmable front and rear lock, cruise, four-wheel drive, and upshift indicators.
• Rear Window Defogger Control  - The EMIC provides control and timer functions for the output to the rear window defogger on vehicles so equipped, which eliminates the need for a separate control and timer module for the rear window defogger system. See HEATED GLASS/DEFOGGERS article.
• Vacuum Fluorescent Display Synchronization  - The EMIC transmits electronic panel lamp dimming level messages which allows all other electronic modules with Vacuum Fluorescent Display (VFD) units on the PCI data bus to coordinate their illumination intensity with that of the EMIC VFD unit.

The EMIC houses six analog gauges and has provisions for up to seventeen indicators (Fig. 3). The EMIC includes the following analog gauges:

• Coolant Temperature Gauge 
• Fuel Gauge 
• Oil Pressure Gauge 
• Speedometer 
• Tachometer 
• Voltage Gauge 

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. The EMIC includes provisions for the following indicators:

• Airbag Indicator (with Airbag System only) 
• Anti-lock Brake System (ABS) Indicator (with ABS brakes only) 
• Brake Indicator 
• Check Gauges Indicator 
• Cruise Indicator (with Speed Control only) 
• Fog Lamp Indicator (with Front or Rear Fog Lamps only) 
• Four-Wheel Drive (4WD) Indicator 
• Front Lock Indicator (with Off-Road Package only) 
• High Beam Indicator 
• Low Fuel Indicator 
• Malfunction Indicator Lamp (MIL) 
• Rear Lock Indicator (with Off-Road Package only) 
• Seatbelt Indicator 
• Sentry Key Immobilizer System (SKIS) Indicator (with SKIS only) 
• Turn Signal (Right and Left) Indicators 
• Upshift Indicator (with Manual Transmission only) 

The EMIC high beam indicator is illuminated by a dedicated incandescent bulb. Each remaining indicator in the EMIC is illuminated by a dedicated LED that is 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. Cluster illumination is accomplished by dimmable incandescent back lighting, which illuminates the gauges for visibility when the exterior lighting is turned on. Each of the incandescent bulbs is secured by an integral bulb holder to the electronic circuit board from the back of the cluster housing.

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. See SYSTEM WIRING DIAGRAMS article. 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, a VFD unit, the electronic circuit board, the circuit board hardware, the cluster overlay, or the EMIC housing are damaged or faulty, the entire EMIC module must be replaced. The cluster lens, the cluster hood and mask unit, the cluster housing rear cover, the odometer/trip odometer switch button boot, and the incandescent lamp bulbs with holders are available for individual service replacement.