This commercial driver study guide covers relevant Federal Motor Carrier Safety Administration (FMCSA) Entry-Level Driver Training (ELDT) concepts and California commercial driver knowledge topics. Review the regulations, procedures, and safety checklists below as part of your CDL and commercial learner permit (CLP) preparation.
Why restrictions matter
A restriction removes part of the authority that the CDL class would otherwise provide. Many restrictions come directly from the vehicle or equipment used for the skills test. Before scheduling, compare the test vehicle with the vehicles you expect to operate. Choosing an easier or different test vehicle can produce a license that is valid but unusable for the intended job.
L and Z: air-brake limitations
L — No full air brakes: may be placed when the applicant does not pass the air-brake knowledge test, cannot identify or test the system correctly, or takes the skills test without a full air-brake system. Z — No full air brakes: applies when the skills test vehicle uses air-over-hydraulic brakes. Both codes limit operation of CMVs equipped with full air brakes, but the testing circumstances differ.
E and O: transmission and coupling
E — No manual transmission: results when the skills test is completed in a vehicle with an automatic transmission. O — No tractor-trailer fifth-wheel combination: applies to a Class A test completed with a pintle hook or another non-fifth-wheel connection. A driver planning to operate a manual tractor-trailer should test in a qualifying manual vehicle with the proper fifth-wheel configuration.
M and N: passenger vehicle class
M limits a Class A holder who earns passenger or school-bus authority using a Class B vehicle to Class B and C passenger vehicles. N limits a Class B holder who tests in a Class C passenger vehicle to Class C passenger vehicles. These restrictions show why the passenger test vehicle must represent the highest passenger-vehicle class the driver expects to operate.
V: medical variance
V indicates that FMCSA has issued a medical variance and that information exists in the driver’s CDLIS record. The code does not explain every condition on the face of the card; the driver must comply with the variance, medical certificate, operating limits, and renewal requirements that apply. California may also impose state medical restrictions in appropriate cases.
The N trap
The same letter can appear in different contexts. N endorsement means tank vehicle authority. N restriction limits certain passenger-vehicle operation. On an exam question, first identify whether the question asks about endorsements or restrictions. Never memorize a letter without its column or context.
Removing a restriction
Removing a restriction normally requires correcting the missing qualification and may require a new knowledge or skills test in an appropriately equipped vehicle. Do not assume an employer letter or experience alone removes it. Confirm the current California DMV process, bring the correct vehicle and documents, and complete any required CLP or waiting-period steps.
Scenario: choosing the skills-test vehicle
A driver expects to operate a manual Class A tractor-trailer with full air brakes. A convenient test vehicle has an automatic transmission, air-over-hydraulic brakes, and a pintle-hook trailer. Before scheduling, the driver compares that equipment with the desired privilege and recognizes that the easier vehicle can produce transmission, brake, and coupling restrictions. The driver arranges an appropriately equipped test vehicle rather than earning a credential that will not cover the intended job.
Commercial Driver License Exam Readiness: Achieving a passing grade of 80% or higher on state DMV commercial driver knowledge exams requires mastery of federal vehicle inspection procedures, gross vehicle weight ratings (GVWR / GCWR), braking mechanics, and road safety regulations.