2002 TrailBlazer -- DRLs stay on after car is turned off...

Greetings all. I have a 2002 Trailblazer and recently noticed that the DRLs stay on after the car is turned off. The also stay on when the headlight switch is set to "off". I replaced the headlight switch and that fixed the problem for about a day and now the DRLs stay on after the the car is off again. All of the head/tail/stop/bright/turn light functions work properly otherwise -- only the DRLs cannot be shut off. Any suggestions will surely be appreciated!

Check for a bad relay or dtrl module.