Draining battery on 2003 GMC Yukon XL 1500

For some reason my battery is being drained. I've already replaced the battery, alternator. I have noticed that the passenger seat warmer has not been working as it did. Sometimes it heats up appropriately and some times it does not. I am going to take it to a gmc service shop but since I know absolutely nothing about electrical malfunctions in a vehicle I would appreciate any insight that might be useful.

Asked by for the 2003 GMC Yukon XL 1500
had the same thing, the dealer had to change the dash cluster(gauges) at no charge . there was a problem with shaking levels.