Instrument Cluster: Description

Fig 1: Instrument Cluster

Courtesy of DAIMLERCHRYSLER CORP.

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. See Fig 1. 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, some warning or reminder indications and certain diagnostic information.

Fig 2: Instrument Cluster Components

Courtesy of DAIMLERCHRYSLER CORP.

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. See Fig 2. Just behind the cluster lens is the cluster hood and an integral cluster mask, which are constructed of molded black plastic. Two cluster masks are used; a base black version is used on base models, while a premium black version features a chrome trim ring around the perimeter of each gauge opening and is used on premium models. 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 near the lower edge of the cluster just to the right of the tachometer. The molded plastic EMIC lens, hood and mask unit has three integral mounting tabs, one on each of the lower outboard corners of the unit and one on the upper surface of the hood near the center. These mounting tabs are used to secure the EMIC to the molded plastic instrument panel cluster carrier with two screws at the top, and one screw at each outboard tab.

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 lens, hood and mask unit with six screws. The rear cover includes clearance holes for service access to each of the nine incandescent bulb and bulb holder units installed on the cluster circuit board for general illumination lighting and for the cluster connector receptacle. The single connector receptacle on the back of the cluster electronic circuit board connects the EMIC to the vehicle electrical system through a single dedicated take out and connector of 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 receptacle, the gauges, a Light Emitting Diode (LED) for each cluster indicator, the VFD unit, an audible tone transducer, the cluster overlay, the gauge pointers, the odometer/trip odometer switch and the switch button.

Behind the cluster lens, hood, and mask unit on the face of the cluster housing is the cluster overlay. 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 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 in the overlay at the base of the tachometer dial face has a smoked clear lens through which the illuminated VFD unit can be viewed.

Numerous versions of the EMIC module are offered on this model, in both base and premium trim. 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 Communication Interface (PCI) 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 PCI data bus. (Refer to ELECTRICAL/ELECTRONIC CONTROL MODULES/COMMUNICATION - DESCRIPTION - PCI BUS) .

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 transducer and programming that allows it to provide various audible alerts to the vehicle operator, including chime tones and beep tones. (Refer to ELECTRICAL/CHIME WARNING SYSTEM - DESCRIPTION) .
• 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 lighting.

The EMIC houses four analog gauges, one odometer/trip odometer VFD unit and has provisions for up to twenty-five indicators. See Fig 3. 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 the following analog gauges:

1. Engine Temperature Gauge 
2. Fuel Gauge 
3. Speedometer 
4. Tachometer 

The EMIC includes provisions for the following indicators. See Fig 3:

1. Airbag Indicator 
2. Antilock Brake System (ABS) Indicator 
3. Brake Indicator 
4. Charging Indicator 
5. Coolant Low Indicator (with Diesel Engine only) 
6. Cruise Indicator (in Odometer VFD) 
7. Electronic Throttle Control (ETC) Indicator (with Diesel Engine only) 
8. Four-Wheel Drive Full Time Indicator (with Selec-Trac Transfer Case only) 
9. Four-Wheel Drive Low Mode Indicator (with Four-Wheel Drive only) 
10. Four-Wheel Drive Part Time Indicator (with Four-Wheel Drive only) 
11. Front Fog Lamp Indicator 
12. High Beam Indicator 
13. Light Bar Lamp Indicator (with Light Bar only) 
14. Low Fuel Indicator 
15. Low Oil Pressure Indicator 
16. Malfunction Indicator Lamp (MIL) 
17. Overdrive-Off Indicator (with Automatic Transmission only) 
18. Rear Fog Lamp Indicator (with Rear Fog Lamps only) 
19. Seatbelt Indicator 
20. Security Indicator 
21. Tire Pressure Monitor Indicator 
22. Transmission Overtemp Indicator (with Automatic Transmission only) 
23. Turn Signal (Right and Left) Indicators 
24. Wait-To-Start Indicator (with Diesel Engine only) 
25. Water-In-Fuel Indicator (with Diesel Engine only) 

Fig 3: Gauges & Indicators

Courtesy of DAIMLERCHRYSLER CORP.

Each indicator in the EMIC, except the Cruise indicator located within the odometer/trip odometer VFD unit, is illuminated by a dedicated Light Emitting Diode (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. Refer to the appropriate wiring information in ELECTRICAL. 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 module for this model is serviced only as a complete unit. The EMIC module cannot be adjusted or repaired. If a gauge, an LED indicator, the 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, hood and mask unit and the incandescent general illumination lamp bulbs with holders are available for individual service replacement.