Customers report the ECO Stop/Start is not working. Retailers are testing the primary battery using the Midtronics EXP-1080 tester which is reporting the battery is serviceable. The vehicle then returns with the same Customer concern of ECO Stop/Start inoperative. If a Midtronics GRX-3080 is used, the primary battery fails the test. Replacement of the primary battery resolves the concern.