warning lights stay on on 2004 Chevrolet Trailblazer

warning lights come on checked with code reader and got no codes

Asked by for the 2004 Chevrolet Trailblazer
Exactly which warning lights are on?
lately its been the ABS, airbag, and Reduced Engin Power lights but on occasion all lights are on. The other day while the truck was running i opened the tailgate, after closing the tailgate i noticed that the gate Ajar light staied on eventhough the interior lights tuned off. its got me confused. even when lights were on i noticed no problems and got no codes on the code reader