The automatic transmission on all 1981 models use a Transmission Converter Clutch (TCC). The ECM controls the converter by means of a solenoid mounted in the transmission. When the vehicle speed reaches a certain level, the ECM energizes the solenoid and allows the torque converter to mechanically couple the transmission to the engine. When the operating conditions indicate that the transmission should operate as a normal fluid coupled transmission, the ECM will deenergize the solenoid. Depressing the brake will also return the transmission to normal automatic operation.