Vehicle Inspection and Basic Control
This domain tests the pre-trip inspection sequence and the basic control skills a Minnesota CDL driver must demonstrate: starting, steering, stopping, and checking air brakes. The exam expects specific checks, not a general walk-around.
What the pre-trip must cover
- Engine compartment: fluids, belts, hoses, steering linkage, suspension, brake chambers, and slack adjusters.
- Walk-around: lights and reflectors, tires and wheels, mud flaps, cargo securement, and coupling devices.
- Cab: gauges, controls, mirrors, seat belt, emergency equipment, and horn.
- Brake checks: air pressure buildup, static leak, applied leak, low-air warning, and spring brake application.
Air brake test numbers
With a fully charged system, engine off and parking brake released, pressure loss should not exceed 3 psi per minute for a single vehicle or 4 psi for a combination. Hold the brake pedal and repeat; the same limits apply. The low-air warning must activate between 55 and 75 psi. Spring brakes must apply by the time pressure falls to 20–45 psi.
Basic control
Keep both hands on the wheel, aim high, and make smooth inputs. Accelerate and stop progressively; do not fan the brake pedal. Use reference points and mirrors to hold lane position.
Worked example
A driver hears the low-air buzzer at 60 psi on a straight road. Reasoning: 60 psi is inside the 55–75 psi warning range, so the system is losing pressure too soon. The correct response is to stop safely, set the parking brake, and find the leak; continuing risks spring brake application at 20–45 psi and loss of control.
Traps that cost marks
Confusing the 3 psi single-vehicle limit with the 4 psi combination limit; forgetting to chock wheels before crawling under; assuming ABS removes the need to check slack adjusters.