Control device for automatic transmission

A control device for an automatic transmission of a vehicle comprising:

• a position sensor having multiple switches, each of which generates “ON” signal or “OFF” signal depending on a selected position of a shift lever to be operated by a vehicle driver;
• a transmission control unit having a signal input portion for receiving the “ON” signals and “OFF” signals from the respective switches;
• a first memory portion provided in the transmission control unit and memorizing a map of signal patterns, which correspond to combinations of the “ON” and “OFF” signals from the respective switches at the respective selected positions of the shift lever, when those switches operate in order, wherein the map of signal pattern includes data for changes of the signal patterns which are caused by a movement of the shift lever from one selected position to another position;
• a second memory portion provided in the transmission control unit for memorizing the “ON” and “OFF” signals inputted into the signal input portion from the switches;
• a malfunction determining portion provided in the transmission control unit for comparing a signal pattern as well as a change of the signal patterns memorized in the second memory portion with the signal pattern as well as the change of the signal patterns memorized as the map of signal patterns in the first memory portion, wherein the malfunction determining portion determines that a malfunction has occurred in the position sensor when at least one of the signal patterns and the change of the signal patterns of the second memory portion does not coincide with any of the signal patterns or the changes of the signal patterns memorized in the first memory portion.