Instrument Cluster / Carrier: Description and Operation

MECHANICAL INSTRUMENT CLUSTER

Description
The mechanical instrument cluster is an electromechanical module which receives most of its information directly from the various control modules, via the PCI data bus.

The cluster includes:
- Speedometer
- Tachometer
- Vacuum Fluorescent Display (VF) odometer/trip odometer and transmission range indicator with automatic transmission
- Fuel gauge
- Temperature gauge

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
- Front and Rear Fog lamps (optional)
- Vehicle Theft Security System alarm LED indicator (optional)
- Turn signals

VF display warnings:
- Low Wash
- Door
- Deck

The gauges are the magnetic air-core type. Pointers should rest at or below the low graduation.

It receives its information from the Body Control Module (BCM), Powertrain Control Module (PCM), Transmission Control Module (TCM), Controller Anti-Lock Brakes (CAB), and Occupant Restraint Controller (ORC), via the PCI data bus. Upon receipt of information, the cluster will determine the gauge position and whether the PCI bus controlled warnings should be turned ON or OFF.

- The ABS is a learned feature by receiving an ABS message on the bus. Once learned, the ABS must be unlearned manually by sending a diagnostic message or revising the PID value.
- The AIRBAG light is always supported, but can be unlearned automatically by using the VIN information and the non-receipt of AIRBAG messages. Receipt of AIRBAG messages will override non-air-bag VIN information.
- The PC board is configurable for Auto-Stick (A/S) or Non Auto-Stick vehicles. The cluster provides the information via the PCI bus. The TCM will learn A/S or non A/S vehicle configuration per cluster information on the bus.
- The cluster is set to support vehicles equipped with a TCM (automatic transmission). In MTX (manual transmission) vehicles, the cluster will turn OFF gear information upon receipt of vehicle configuration from the PCM. At initial power-up, you might be able to potentially see the ATX gear letters. Once the MTX information is received, the gear letters will be turned OFF.

Operation
The Mechanical Instrument Cluster (MIC) is divided into 4 sections. Primary gauges (Speedometer and Tachometer), secondary gauges (Fuel Level, Engine Coolant Temperature), PCI bus enabled indicator lamps and hardwired enabled indicator lamps.

The gauge mechanisms function in the same way. The main differences are in the face and size of the gauge.

The Oil Pressure, Brake Warning, Turn Signal and Fog Lamp indicators are directly wired to the circuits that they are indicators for. These indicators are located in, but not controlled by, the MIC and are not part of any MIC self test or diagnostic. All indicators are replaceable bulbs or LEDs.

The PCM sends a gauge position message to the BCM through the PCI bus. The MIC receives this message from the BCM, translates it, and positions the gauges. The BCM also sends messages to the MIC to actuate all PCI controlled indicators. These messages are received when the Ignition Switch is in the RUN or START position.

When the ignition switch is turned to the RUN position, a bulb-check is performed. This consists of activating the PCI bus controlled indicators for approximately 2 to 4 seconds. By holding the TRIP/RESET button in while turning the Ignition Switch to the RUN position, you can activate the MIC Self Test.

The following indicators are controlled by PCI bus messages:
- Malfunction Indicator Lamp
- Charging System Warning Indicator
- Engine Coolant Temperature Indicator
- Cruise Engaged Indicator
- Airbag Warning Indicator
- Low Fuel Indicator
- ABS Warning Indicator
- High Beam Indicator

The following indicators are hardwired and not controlled by PCI bus messages:
- Seat Belt Indicator
- Oil Pressure Indicator
- Brake Warning Indicator
- VTSS Indicator
- Turn Signal Indicators
- Fog Lamp Indicators