15038 - DEALER MESSAGE ONLY. SELECT 2015 VEHICLES WILL RECEIVE A SOFTWARE DOWNLOAD VIA ONSTAR® TO UPDATE THE SOFTWARE FOR THE ELECTRONIC CLIMATE CONTROL (ECC) SYSTEM. THE UPDATE WILL BE PERFORMED ON DEALER INVENTORY VEHICLES, WITH THE UPDATE OCCURRING DURING THE NIGHT TIME HOURS OF 1AM TO 5AM EDT. UPDATES WILL BE ROLLED OUT TO THE INVENTORY STARTING 6/29/2015 AND COMPLETE BY END OF SEPTEMBER 2015. NO FURTHER ACTION IS REQUIRED BY THE DEALER. THIS UPDATE WILL TAKE APPROXIMATELY 15 MINUTES.