Instrument Cluster: Operation: Notes

WARNING: This page is about a different car, the 2004 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.

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 powertrains, 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. (Refer to COMMUNICATION ).

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. However, when abnormal conditions exist, such as high coolant temperature, the algorithm can drive the gauge pointer to an extreme position and the microprocessor can turn on an indicator and generate an electronic chime request message to the Central Timer Module (CTM) over the PCI data bus to sound an audible chime to provide distinct visual and audible indications of a problem to the vehicle operator.

The EMIC circuitry operates on battery current received through a fused B(+) fuse in the Junction Block (JB) on a non-switched fused B(+) circuit, and on battery current received through a fused ignition switch output (run-start) fuse in the JB on a fused ignition switch output (run-start) circuit. This arrangement allows the EMIC to provide some features regardless of the ignition switch position, while other features will operate only with the ignition switch in the On or Start positions. The EMIC circuitry is grounded through two separate ground circuits. One of these ground circuits receives ground through a take out of the instrument panel wire harness with an eyelet terminal connector that is secured by a nut to a ground stud located on the left cowl side inner panel below the instrument panel, while the other ground circuit receives ground through a take out of the headlamp and dash wire harness with an eyelet terminal connector that is secured by a nut to a ground stud located on the left front fender inner shield near the battery in the engine compartment.

The EMIC also has a self-diagnostic actuator test capability, which will test each of the PCI bus message-controlled functions of the cluster by lighting the appropriate indicators, positioning the gauge needles at several predetermined calibration points across the gauge faces, and illuminating all segments of the odometer/trip odometer and, if so equipped, the gear selector indicator Vacuum-Fluorescent Display (VFD) units. (Refer to DIAGNOSIS AND TESTING - INSTRUMENT CLUSTER ). See the owner's manual in the vehicle glove box for more information on the features, use and operation of the EMIC.