There are no relays to remove or replace in an 06. They are a totally different animal than previous models. The lighting is controlled by the TIPM, or Totally Integrated Power Module under the hood. 06 was the first year for this module in pickups and replaces the FCM/IPM assembly. A scan tool will be helpful in accessing DTCs in the TIPM to figure out your problem. Other than that check for loose or corroded terminals in the connectors under the TIPM.