Instrument Cluster / Carrier: Description and Operation
GENERAL INFORMATIONElectro/Mechanical Instrument Cluster
The mechanical instrument cluster is an electromechanical module which receives most of its information from the Body Control Module (BCM) via the CCD bus.
Cluster:
The cluster includes:
- 200 km/h (120 MPH) speedometer
- Tachometer
- Odometer/trip odometer and transmission range indicator with automatic transmission
- Fuel gauge
- Temperature gauge
- Security alarm indicator (optional)
The warning and information indicators include the following:
- Service Engine Soon (Check Engine)
- Airbag
- Charging system
- Low oil pressure
- High temperature
- Low fuel
- Seat belt
- Cruise
- Brake/park brake
- Anti-lock brake system
High beam
- Fog lamps
- Vehicle Theft Security System alarm LED indicator (optional)
- Turn signals
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
Autostick Odometer/Transmission Range Indicator:
Auto Stick
Vehicles with Autostick will have a unique Transmission Range Indicator display. When in the Autostick mode, the Transmission Range Indicator will display 1, 2, 3 or 4 to inform the driver which transmission gear is currently engaged.
Compass/Temperature Mini-Trip Computer:
CTMC Module:
Compass/Temperature Mini-trip Computer
The Compass/Temperature Mini-Trip Computer (CMTC) system is located on the right hand side of the instrument panel cluster. The CMTC is an electronic control module with a vacuum fluorescent display and two function buttons. The CMTC is capable of displaying compass, temperature, and trip computer information. Actuation of the STEP button will cause the CMTC to change mode of operation and actuation of the US/M button will toggle between English and Metric unit of measurement. A reset of the trip computer information is accomplished by actuating the Step and US/M buttons simultaneously.
The CMTC is active only when the ignition switch is in the ON position. When the ignition switch is turned ON, the CMTC will turn on all of the segments in the display for one second then return to the last function screen that was displayed prior to the ignition being turned OFF.
The functions that are available via activation of the STEP switch are as follow:
- Compass and Ambient Temperature
- Average Trip Fuel Economy (AVG ECO)
- Estimated Range (RANGE)
- Present Fuel Economy (ECO)
- Trip Odometer (ODO)
- Elapsed Ignition On Time (ET)
- Blank Screen (OFF)
Compass
The CMTC is an auto-calibrating compass and requires no activation of any switches to trigger a forced calibration. The compass is initially setup to be calibrated for earth fields of approximately 180 milligauss. However, due to the variation in the magnetic earth field across the country and the variation of the magnetic structure from vehicle to vehicle the compass may need to be calibrated. Refer to Instrument Panel, Gauges and Warning Indicators/Compass/Testing and Inspection/Procedures/Compass Calibration Service Procedures.
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 OC. If the message CCD bus to display the ambient temperature.
Mini Trip Computer Messages
The Mini Trip Computer data is obtained from information put on the CCD bus from thee Powertrain Control Module and the Body Control Module. The CMTC will not display information for any of the screens for which it did not receive the proper data over the CCD bus for that particular screen. In which case the message CCD will be displayed. If the CCD message is displayed on all the screens of the CCD bus with a scan tool (DRB). If some of the screens appear to be functioning properly but some of the screens display CCD then check either the Powertrain Control Module or the Body Control Module for proper CCD bus communications. If the CCD message still persist refer to the Mini Trip Computer Self Diagnostic Test.
Data Link Connector
Data link connector is located on the left side kick panel just above hood release.
CIRCUIT OPERATION
Instrument Cluster
The Instrument Cluster, located on the left side of the instrument panel, provides the operator with gauges and warning lamps indicating vehicle operation. All gauges, regardless of engine type, are driven by the CCD Bus from the Body Control Module (BCM).
The indicator lamps for the Seat Belt, Charging System, Vehicle Speed Control (Cruise), Airbag, Check Engine (Malfunction Indicator Lamp), Low Fuel, High Beam, and Engine Coolant Temperature are also driven by the BCM.
Battery voltage for the instrument cluster is provided from two different sources. One is the F33 circuit which supplies battery voltage for the duster. This circuit is protected by 20 amp fuse and located in cavity 7 of the junction block. Power for the fuse is supplied by circuit A13. This fuse is HOT at all times and protected by a 40 amp fuse located in cavity 14 of the Power Distribution Center (PDC). Circuit A13 also supplies power to the fuses for the horns, and the cigar lighter.
The second power source for the cluster is the F11 circuit. This circuit is HOT in the OFF, START, and RUN positions. The F11 circuit is protected by a 10 amp fuse located in cavity 11 of the junction block.
Illumination lamps, internal to the cluster, receive battery voltage on the E2 circuit. This circuit originates in the BCM and lamp intensity is controlled by the BCM. Ground for the lamps is provided on the Z1 circuit and terminates at the instrument panel left side cowl.
Instrument Panel Lamp Dimming
The Body Control Module (BCM) controls the instrument panel lamp intensity using input from the dimmer switch, circuit E19. The BCM uses the CCD Bus to send a signal to the instrument cluster for proper lamp intensity.