Instrument Cluster / Carrier: Description and Operation

DESCRIPTION
Instrument Panel System
The instrument panel serves as the command center of the vehicle, which necessarily makes it a very complex unit. The instrument panel is designed to house the controls and monitors for standard and optional powertrains, climate control systems, audio systems, lighting systems, safety systems and many other comfort or convenience items. The instrument panel is also designed so that all of the various controls can be safely reached and the monitors can be easily viewed by the vehicle operator when driving, while still allowing relative ease of access to each of these items for service. See the owner's manual in the vehicle glove box for more information on the features, use and operation of all of the instrument panel components and systems.

Instrument Panel
This instrument panel uses a full-width structural plastic foundation as its primary support. When the three primary molded plastic components of this structure are vibration welded together they provide superior instrument panel stiffness and integrity to help reduce buzzes, squeaks, and rattles even on the bumpiest roads.

This type of construction also provides improved energy absorption which, in conjunction with the dual airbag modules and seat belts, helps to improve occupant protection. This foundation structure also serves as the ducting for the heating and air conditioning system panel and defroster outlets, which greatly reduces the number of components used over conventional instrument panel construction.

Modular instrument panel construction allows all of the gauges and controls to be serviced from the front of the panel. In addition, most of the instrument panel electrical components can be accessed without complete instrument panel removal. If necessary, the instrument panel can be removed from the vehicle as an assembly.

Removal of the steering column opening cover provides access to the steering column mounts, the steering column wiring, the gearshift interlock mechanism, the junction block, and much of the instrument panel wiring. Removal of the glove box provides access to the Central Timer Module (CTM), the radio antenna coaxial cable, and additional instrument panel wiring.

Removal of the instrument cluster bezel allows access to the cluster assembly, the radio, the exterior lighting system switches, and the heating and air conditioning controls. Removal of the cluster assembly allows access to the cluster illumination and indicator lamp bulbs, and more of the instrument panel wiring. The instrument panel center bezel contains an ash receiver, a passenger airbag on/off switch, and has provisions for a cigar lighter and an accessory power outlet.

Removal of the complete instrument panel is required for service of the passenger side airbag module and most passenger compartment components of the heating and air conditioning systems.

Instrument Cluster
The instrument cluster is an electromechanical unit that contains integrated circuitry and internal programming to perform a variety of functions. The instrument cluster circuitry monitors hard-wired switch inputs, as well as message inputs received from other vehicle electronic modules on the Chrysler Collision Detection (CCD) data bus network.

The instrument cluster uses these many inputs along with its internal programming to provide hard- wired chime tone requests to the Central Timer Module (CTM), which performs the functions of the chime warning module on this model. The instrument cluster circuitry also has a self-diagnostic capability. Refer to Instrument Cluster in the Diagnosis and Testing of Instrument Panel Systems for more information on this feature.

The only instrument cluster diagnosis consists of confirming the viability of the hard-wired chime request circuit between the instrument cluster circuitry and the CTM, and diagnosis of the hard-wired seat belt switch input to the instrument cluster. For diagnosis of the CCD data bus and the data bus message inputs, a DRB scan tool and the proper Diagnostic Procedures are recommended.

Refer to Service and Repair for instrument cluster service procedures. Refer to the Testing and Inspection for more information on the remaining hard-wired instrument cluster inputs. The instrument cluster chime warning circuitry cannot be repaired and, if faulty or damaged, the instrument cluster assembly must be replaced.

MECHANICAL INSTRUMENT CLUSTER (MIC)
The MIC is available in 4 different versions. Two of the versions are Canadian clusters. There is a highline and a low line cluster available. The difference is the addition of a tachometer in the highline. In order to accomplish this, the fuel level gauge is reduced in size and oil pressure gauge is relocated. The cluster positions it's gauges with bus messages received from the PCM. The odometer is a Liquid Crystal Display (LCD). The cluster will provide bus bias and the PCM provides termination.

The MIC has an internal diagnostic routing that can be accessed by pushing and holding the trip odometer while rotating the key to the on position. The cluster will then place all the gauges at their calibration points and will light all the CCD driven tell-tales. It will also light all the segments of the LCD display for a visual verification check.

The MIC can verify communications with the PCM, ID the module, or change the country code by using options 1, 3, or 9 on the DRB III(R) under the MIC menu. If there are faults found during the diagnostic routine, the cluster will report them on the LCD odometer display. For further information about the diagnostic routine and the explanation of the faults, refer to Instrument Panel Testing and Inspection. If additional computer diagnosis is required, refer to Body Control Module, Testing and Inspection.

OPERATION
Instrument Cluster
Two basic instrument cluster options are offered on this model, standard and rallye. Both clusters are electromechanical units that utilize integrated circuitry and information carried on the Chrysler Collision Detection (CCD) data bus network for control of all gauges and many of the indicator lamps. These clusters also incorporate a digital Vacuum Fluorescent Display (VFD) for the odometer/trip odometer display functions. Some variations of these clusters exist due to optional equipment and regulatory requirements.

Both of these clusters include the following analog gauges:
- Coolant temperature gauge
- Fuel gauge
- Oil pressure gauge
- Speedometer
- Voltmeter.

These clusters also include provisions for the following indicator lamps:
- Airbag indicator lamp
- Anti-lock Brake System (ABS) lamp
- Brake warning lamp
- Check gauges lamp
- Cruise-on indicator lamp (programmable)
- Four-wheel drive indicator lamps (part-time and full-time)
- Headlamp high beam indicator lamp
- Low fuel warning lamp
- Low washer fluid warning lamp
- Malfunction indicator (Check Engine) lamp
- Overdrive-off indicator lamp (automatic transmission - programmable)
- Seat belt reminder lamp
- Security lamp
- Transmission oil temperature warning lamp (automatic transmission - programmable)
- Turn signal indicator lamps
- Upshift indicator lamp (manual transmission - programmable).

The optional rallye cluster includes all of the gauges and indicator lamps found in the standard duster, but adds an analog tachometer. Some of the standard cluster gauges have different positions or sizes in the rallye cluster in order to accommodate the tachometer.

Both instrument clusters include a provision for mounting the automatic transmission gear selector indicator in the lower right corner of the cluster. Models equipped with a manual transmission have a block-out plate installed in place of this indicator.

The instrument cluster circuitry has a self-diagnostic actuator test capability, which will test each of the CCD bus message-controlled functions of the cluster by lighting the appropriate indicator lamps and positioning the gauge needles at several predetermined locations on the gauge faces in a prescribed sequence. For more information on this function, refer to Testing and Inspection.

The instrument cluster circuitry also sends chime tone requests over a hard wired circuit to the Central Timer Module (CTM) when it monitors certain conditions or inputs. The CTM replaces the chime or buzzer module.

The instrument cluster for this model is serviced only as a complete unit. If a cluster gauge or the cluster circuit board are faulty, the entire cluster must be replaced. The cluster lens, the cluster hood, the rear cluster housing cover, and the incandescent lamp bulbs and holders are available for service replacement.

Gauge
With the ignition switch in the On or Start positions, voltage is supplied to all gauges through the instrument cluster electronic circuit board. With the ignition switch in the Off position, voltage is not supplied to the gauges. The gauges do not accurately indicate any vehicle condition unless the ignition switch is in the On or Start positions.

All of the instrument cluster gauges, except the odometer, are air core magnetic units. Two fixed electromagnetic coils are located within the 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 shaft. 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 instrument cluster electronic circuitry in response to messages received on the Chrysler Collision Detection (CCD) data bus network.

The gauge needle moves as the movable permanent magnet aligns itself to the changing magnetic fields created around it by the electromagnets. The instrument cluster circuitry is programmed to move all of the gauge needles back to the low end of their respective scales after the ignition switch is turned to the Off position.

Indicator Lamp
Indicator lamps are located in the instrument cluster and are served by the cluster circuit board and connectors. Many of the indicator lamps in the instrument cluster are controlled by the instrument cluster circuitry in response to messages received over the Chrysler Collision Detection (CCD) data bus network.

The four-wheel drive indicator lamps (part-time and full-time), headlamp high beam indicator lamp, low washer fluid warning lamp, security lamp and turn signal indicator lamps are hard wired. The seat belt reminder lamp is controlled by the instrument cluster programming and by CCD data bus messages from the Airbag Control Module (ACM). The brake warning lamp is controlled by a hard wired input from the park brake switch and by CCD data bus messages from the Controller Anti-lock Brake (CAB). The instrument cluster circuitry uses CCD data bus messages from the Powertrain Control Module (PCM), ACM, and CAB to control all of the remaining indicator lamps.

In addition, certain indicator lamps in this instrument cluster are programmable. This feature allows those indicator lamps to be activated or deactivated with a DRB scan tool through the instrument cluster electronic circuitry for compatibility with certain optional equipment. The programmable indicator lamps for this model include the cruise-on indicator lamp, the overdrive-off indicator lamp, the transmission oil temperature warning lamp and the upshift indicator lamp.

Each of the red indicator lamps in the instrument cluster is illuminated by a dedicated Light-Emitting Diode (LED). If an LED should fail, the entire instrument cluster must be replaced. The remaining indicator lamps in the instrument cluster use incandescent bulbs and holders. Each incandescent indicator lamp has a replaceable bulb and bulb holder.