Just purchased this Yukon XL a few days ago. Noticed that the airbag light, ABS, battery light all went on. The message board read check 4wheel drive and all the instrument panels went dead. The odometer and tach still worked. After a few minutes, I heard a ding and everything started working again. Then happened again later in the day, this time as I was parking at a store. When I came back out 15 minutes later, everything worked fine. Any ideas what to check?