Application of an Electronic Instrument Cluster as a Node in a Multiplexed Vehicle Electrical System 2001-01-2738
The primary function of a gauge and information display cluster is to report to the driver the current state of the different systems of the vehicle and particularly to report out of range performance conditions. This paper will examine one implementation of the instrument cluster as a node on the J1939 data link as it relates to that functionality. Traditionally clusters have received their information from a variety of sensors requiring a substantial number of connections. Once the cluster is installed in the vehicle, changing the configuration may only be accomplished by means of a hardware change. Today's multiplexed instrument cluster also receives and processes information from a variety of sources for display as gauge data, warning light status, and selected gear information, specifically from the engine controller, electrical system controller, and the transmission controller, but with a significant reduction in the number of electronic, hydraulic, and pneumatic connections to the module. This is ultimately due to the roll the instrument cluster plays as a node on the data link. Because the cluster is a node, sensors need not be directly connected to it. Instead the cluster receives data from other nodes in the system. Along with the reduction of sensors, a central benefit of the multiplexed system is an increase in the configuration flexibility. Additional gauges may be added to the cluster without adding any wiring. The cluster gauges and warning lights are configurable based on data from an electrical system control module. There is also an increased flexibility in messages configured based on engine and transmission. The gear selection graphic or PRNDL on the integral digital display can also be reconfigured for use with a variety of transmissions. The multiplexed cluster is also capable of displaying additional diagnostic information in its supplemental digital display along with storing and broadcasting diagnostic messages on the data link. Being a part of a multiplexed vehicle system greatly improves the instrument cluster's functionality as a fault-reporting device.