If a farm tractor does not conform to applicable express written warranties and the consumer reports the nonconformity to the manufacturer and its authorized dealer during the term of the express written warranties or during the period of one year following the date of the original delivery of the farm tractor to the consumer, whichever is earlier, the manufacturer or its authorized dealers shall make the repairs necessary to make the farm tractor conform to the express written warranties, notwithstanding that the repairs are made after the expiration of the warranty term or the one-year period. For a self-propelled vehicle this section is limited to warranties on the engine and power train.