Instrument Cluster - Operation

OPERATION

The microprocessor-based Instrument Cluster (IC) hardware and software uses various inputs to control the gauges and indicators visible on the face of the IC. The Vehicle Theft Alarm (VTA) lamp input is hard wired, the remaining inputs are in the form of electronic messages that are transmitted by other electronic modules over the Controller Area Network (CAN) data bus. Communication - Operation.

The IC may also produce audible warnings for other electronic modules in the vehicle based upon electronic tone request messages received over the CAN data bus. Each audible warning is intended to provide the vehicle operator with an audible alert to supplement a visual indication.

The IC circuitry operates on battery current received through a non-switched fused B(+) circuit and on battery current received through a fused ignition output (run-start) circuit. This arrangement allows the IC to provide some features regardless of the ignition switch status, while other features will operate only when the status of the ignition switch is ON or START. The circuitry is grounded through a ground circuit of the instrument panel wire harness.

The IC also has a self-diagnostic test capability that tests each of the CAN bus message-controlled functions of the IC. This test illuminates the appropriate indicators, positions the gauge needles at several predetermined calibration points across the gauge faces and illuminates all segments of the EVIC TFT display. The EVIC will display the hardware/software version, and the CAN Vehicle Maintenance Monitor (VMM) used in the IC. Instrument Cluster.

THIN FILM TRANSISTOR DISPLAY

The Thin Film Transistor (TFT) display unit is integrated into and soldered onto the IC electronic circuit board. With the status of the ignition switch OFF or ACCESSORY, the TFT display is activated when the driver door is opened (Rental Car mode) and deactivated when the driver door is closed. Otherwise, the display unit is active when the ignition switch status is ON or START, and inactive when the ignition switch status is OFF or ACCESSORY.

The IC TFT display unit has several display capabilities. The TFT unit displays odometer, trip odometer, gear selector indication (PRNDL) for models with an automatic transmission, several warning or reminder indications and various diagnostic information when certain fault conditions exist. The push buttons in the EVIC switch pod on the left horizontal spoke of the steering wheel are used to control some of the display modes of the TFT. Electronic Vehicle Information Center - Operation.

CLUSTER ILLUMINATION

Instrument Cluster (IC) general illumination lighting is supplied by several Light Emitting Diode (LED) units controlled by the IC, and are illuminated at full intensity anytime the ignition switch status is ON or RUN. The illumination intensity of these lamps can be adjusted only when the vehicle exterior lighting is turned ON by rotating the panel lamps dimmer thumbwheel of the dimmer module (down to dim, up to brighten). The IC monitors a CAN bus input from the Body Control Module (BCM) to determine illumination intensity.