After completing the pre-trip air brake checks, what is the last step before putting the vehicle in service?

Explanation

The last step of the pre-trip air brake check is a service brake road test: with full air pressure restored, let off the parking brake, ease the vehicle into a slow roll, then press the brakes firmly, watching for the vehicle pulling to one side, anything that feels off, or a lag before it actually stops. 49 CFR 383.111(b)(5) requires CDL applicants to know the procedures for conducting safe and accurate pre-trip inspections, the required-knowledge area this final verification step falls under; the specific slow-speed road test procedure is standard driver-training content from the manual, not spelled out in the CFR paragraph itself. Driving at highway speed first is wrong and unsafe; the test is meant to catch a problem at low speed, before the vehicle is trusted at full speed. Skipping the road test because the gauges read normal is wrong because gauges only show air pressure, they cannot detect a mechanical problem like uneven braking or a delayed response. Watching only the brake lights from behind is wrong because that confirms the lights work, not that the brakes themselves are functioning correctly.

Source: 49 CFR 383.111(b)(5)