Do you need an air brake endorsement to drive a vehicle under 26000 pounds with air brakes in ca?

On a US drivers licence, there is no air brake endorsement - there is only an air brake restriction, and it is only applicable to CDL licences and commercial vehicles. Vehicles of 26,000 lbs. or less GVWR only require a CDL if they're hauling hazardous materials, or if they're designed to transport more than 15 persons (including the driver). Otherwise, most states will allow you to drive it on the same licence you use to drive any regular passenger car, without any requirement to be trained in the proper use of air brakes.