In a dual air system, if the secondary (front brake) circuit suffers a total failure, what happens to the vehicle's braking capability?

1. Complete braking failure occurs and the steering wheel locks up
2. The primary circuit will still stop the rear wheels, but front axle braking is lost and stopping distances will increase
3. The trailer emergency brakes apply instantly, locking all trailer wheels
4. The compressor governor will fail to cut in, causing pressure to drain from all tanks