ABS and Brake Light comes on when outside temps is over 85 degrees


I have a 2003 Chevy Silverado. Every time the truck sits outside and the tempeture reaches 85 degrees, the ABS and Break Lights on the dash will remain on when I start the truck. I still have brakes. What’s strange is if I have the A/C on, the two lights will eventually go out when the interior is cooled down. Everytime I took it in to see if it was the sensor, the truck would not do it. So am I crazy? Or is the truck playing a practical joke on me?


My guess is the parking brake switch.