Instrument Cluster / Carrier: Description and Operation

GENERAL INFORMATION

Electro - Mechanical Instrument Cluster
The mechanical instrument cluster is an electro-mechanical module which receives most of its information from the Body Control Module (BCM) via the CCD bus.

Electro-Mechanical Instrument Cluster (MIC):

The cluster includes:
- 120 mph (200) km/h speedometer
- Tachometer
- Odometer/trip odometer and transmission range indicator with automatic transmission
- Door ajar
- Deck ajar
- Lo washer fluid
- Fuel gauge
- Temperature gauge
- Vehicle Theft/Security System (VTSS) indicator (optional)

- The warning and information indicators include the following:
- Check Engine
- Airbag
- Charging system
- Low oil pressure
- High temperature
- Low fuel
- Seat belt
- Cruise (optional)
- Brake/park brake
- Anti-lock brake system (optional)
- High beam
- Fog lamps
- Vehicle Theft/Security System (VTSS) indicator (optional)
- Turn signals
- Traction Control ON/OFF

The gauges are the magnetic air-core type. When the ignition switch is OFF, the gauge pointers should rest at or below the low graduation.

SYSTEM OPERATION

Mechanical Instrument Cluster (MIC)
The Body Control Module sends the angular position of four gauges, the status of seven indicator lamps and the status and dimming of the PRNDL indicator (VF display). It also sends information of the dimming of cruise and low fuel lamps to the mechanical instrument cluster (MIC) over the CCD bus when the ignition is in the "OFF" (unlock), "RUN" or "START" positions. The PRNDL indicator works when the ignition is in the "OFF", "RUN" or "START" positions; all other MIC features work only when the ignition is in the "RUN" position. On transition of the ignition from the "OFF" to the "RUN" position, a bulb check is performed. This consists of activating all CCD-controlled indicator lamps and all PRNDL segments for approximately two to four seconds. The PRNDL bulb check is aborted if the gear selector is moved from the PARK position, or if the tachometer exceeds 450 rpm. The ABS warning lamp is hard wired to the cluster. However, if communication is lost to the ABS module, the MIC will turn on the warning lamp.

A new diagnostic feature has been added to the cluster software. If the cluster loses bus communication specifically with the Powertrain Control Module for more than 20 seconds, the MIL lamp will turn on and the "No Bus" message will be shown in the VF display. If communications are reestablished, then both the MIL lamp and VF display are cleared. It is important to note that no DTC's will be set.

Ambient Temperature
The temperature is displayed in whole degrees, Celsius or Fahrenheit. Temperatures greater than or equal to zero are displayed unsigned and temperatures below zero are displayed signed (-). If the temperature is more than 55° C (131° F) or the temperature sending line is shorted to ground, the compass and ambient temperature screen will display SC. If the temperature is less than -40° C (-40° F) or the temperature sending line is an open circuit, the compass and ambient temperature screen will display "OC". If the CMTC is not receiving the temperature information over the CCD Bus, then the compass and ambient temperature screen will display "CCD". Refer to the proper Body Diagnostic Procedures.