An Automotive Electronic Instrument Cluster with a Programmable Non-Volatile Odometer

An electronic instrument cluster for the 1985 Chrysler H-Body car line, that resulted from a collaborative effort between the Chrysler Corporation and Motorola, Inc., is described. The intelligence of a microprocessor is used to control several vacuum fluorescent displays that provide the vehicle operator with speedometer, odometer, trip odometer and tachometer readings as well as the displays for oil pressure, vehicle system voltage, engine coolant temperature and fuel level. Various challenges that resulted from replacing the electromechanical cluster technology (in this particular application) with electronics, are described as well as the methods used to surmount them. Also described is how the non-volatile electronic odometer can be preset. The cluster has a self-diagnostic capability and a means of conveying information from the Electronic Fuel Injection (EFI) computer to the service technician. Incandescent bulbs are used for the warning and indicator lamp functions. Speed and distance values can be presented in either English or metric units at the option of the vehicle operator.