Instrument Cluster

The ElectroMechanical Instrument Cluster (EMIC) is designed to allow the vehicle operator to monitor the conditions of many of the vehicle components and operating systems. The gauges and indicators in the EMIC provide valuable information about the various standard and optional powertrain, fuel and emissions systems, cooling systems, lighting systems, safety systems, and many other convenience items. The EMIC is installed in the instrument panel so that all of these monitors can be easily viewed by the vehicle operator when driving, while still allowing relative ease of access for service. The microprocessor based EMIC hardware and software uses various inputs to control the gauges and indicators visible on the face of the cluster. Some of these inputs are hard wired, but most are in the form of electronic messages that are transmitted by other electronic modules over the Programmable Communications Interface (PCI) data bus network.

The EMIC microprocessor smooths the input data using algorithms to provide gauge readings that are accurate, stable and responsive to operating conditions. These algorithms are designed to provide gauge readings during normal operation that are consistent with customer expectations. When abnormal conditions exist, such as low/high battery voltage, low oil pressure, or high coolant temperature, the algorithm drives the gauge pointer to an extreme position and the microprocessor turns on the "Check Gauges" indicator to provide a distinct visual indicational of a problem to the vehicle operator. The instrument panel circuitry may also generate a chime tone when it monitors certain conditions or inputs to provide the vehicle operator with an audible alert.

The EMIC circuitry operates on battery current received through the Ignition-Off Draw (IOD) fuse in the PDC on a non-switched fused B+ circuit, and on battery current received through a fuse in the fuse block on a fused ignition switch output (run-start) circuit. This allows the EMIC to provide chime service and interior lighting control regardless of the ignition switch position, while other features will operate only with the ignition switch in the ON or START positions.

All gauges receive battery current through the EMIC circuitry when the ignition switch is in the ON or START positions. With the ignition switch in the OFF position battery current is not supplied to any gauges, and the EMIC circuitry is programmed to move all of the gauge needles back to the low end of their respective scales.