System for detecting shifter position sensor malfunction

摘要

A system for detecting malfunction of a transmission of a vehicle, more particularly a system for detecting a failure of a shift lever position sensor for a vehicle automatic transmission is provided with two detection modes based on urban driving and open-road driving. The number of times that the vehicle speed goes up and down between prescribed upper and lower values separately defined for the two modes is counted, when the shift lever position signal is absent. Probable failure is judged when the number of times reaches eight in the first mode and sensor failure is confirmed when the number of times reaches three in the second mode. Shift lever position sensor failure can be reliably detected irrespective of whether the driving environment is urban or open-road.