On my 2006 Silverado the brake light comes on frequently when starting the vehicle and “check brake system” comes on at the same time. Been to two shops; fluid is full, changed out an expensive module with no change so reinstalled the old one, unplug the master cylinder sensor with no change. One garage said it may be something in the dash. Apparently this is a common problem. Never goes away when vehicle is running. Occasionally I will stop and restart the vehicle and it will go away. Light and warning only came on once while driving down the road. Almost always happens on startup. The ABS light never comes on. No codes from this. Any ideas on correcting? Thx.