Every commercial truck is required to have a low air warning device. This device can be a warning light, a buzzer or other audible warning, or a wig wag. For those who aren’t old enough to know what a wig wag is, it is a manual warning device that drops down in front of the driver to warn of low air, most had a stop sign on them. Please test your truck’s low air warning device daily. If it is not working, please inform the shop.