Michigan Compiled Laws, Chapter 440. Uniform Commercial Code § 440.2313b

(a) The date from which the goods are delivered to the merchant or the warrantor for a warranteed repair to the date the purchaser is informed that the necessary repair has been completed.

(b) The date from which the merchant or warrantor attempts to make a warranteed repair to the goods at the purchaser's residence, domicile, or place of business to the date the necessary repairs are completed. In addition to this time period, the number of days preceding the date the merchant or warrantor begins a repair during which the goods were inoperative due to the need for a warranteed repair beginning with the date the purchaser notifies the merchant or warrantor in writing that the goods are inoperative and the merchant or warrantor receives the notice.