All 1981 models with an automatic transmission use 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 de-energize the solenoid. Depressing the brake will also return the transmission to normal automatic operation.