An auto transmission technician is a specialist who maintains and repairs car transmissions. In this role, you run tests on the vehicle using computerized diagnostic equipment to determine if there are any problems with the transmission that need to be fixed. Once the results of the tests are ready, you make the necessary repairs or perform routine maintenance, such as changing or flushing out the transmission fluid. After your repairs, you test drive the vehicle and make additional diagnostic assessments to ensure that your repairs solved the problem. You find these mechanics at general repair shops or specialty transmission repair facilities. Some service centers have technicians who rebuild old or damaged transmissions.