L4 ADAS (Driver Assistance) — practice test

High-yield L4 topics

The material that shows up year after year. If you're short on time, start here.

• Calibration prerequisites. Correct tire size and pressure, level floor, curb weight or specified fuel/cargo load, ride height in spec, no roof rack, full battery support with a maintainer (a drop mid-procedure aborts or, worse, stores garbage). Expect a question where every electrical answer is wrong and the fault is that somebody skipped a four-corner alignment before aiming the camera.
• Thrust line vs geometric centerline. Forward-facing camera and radar targets are placed off the thrust line, because that is the direction the vehicle actually travels. A car with a rear thrust angle out of spec will dog-track, and a camera aimed to the geometric centerline will pull LKA to one side even though it calibrated fine. Alignment first, calibration second - always.
• Radar behavior and blockage. Most long/mid-range forward radar sits in the 76-81 GHz band; corner/BSM radar is often 24 GHz legacy hardware. Radar sees through plastic fascia but not through metallic-flake paint, thick body filler, aftermarket emblems, mud, ice, or a plate frame in the beam path. A 'radar blocked/obstructed' DTC is far more often a bumper repair or contamination than a failed module.
• Forward camera and windshield. The camera reads through a specific optical zone: correct wedge angle, correct distortion spec, correct bonded bracket location. Cheap aftermarket glass, tint or a shade band in the camera window, or a bracket off by a few millimeters will cause failed calibrations or lane drift. Windshield replacement means calibration, no exceptions, and OE position statements back this up.
• Static vs dynamic - and who requires what. Static needs targets, exact target distance and height, controlled lighting, no reflective clutter behind the target. Dynamic needs a specified speed range, clear painted lane lines, a lead vehicle for some ACC learns, and enough uninterrupted road time. Some OEs require both, in a set order. Know that the OEM procedure decides, not the tool's menu and not the shop's convenience.
• Feature and network integration. LKA is EPS torque overlay; LDW is only a warning. AEB and ACC borrow the ABS/ESC hydraulic pump and pre-charge. Steering angle sensor zero-point and the yaw rate/lateral accel sensor in the IMU have to be right or the system mis-predicts path curvature. Camera and radar traffic increasingly rides Ethernet (100BASE-T1 unshielded twisted pair) and CAN FD, so a loss-of-communication code can be one crimped wire, not a dead sensor.

Where techs lose points on L4

Good technicians miss these — not from lack of skill, but because the question is built to catch them.

• A completed calibration is not a correct calibration. The tool reports success against whatever reference it was given. Sloppy floor slope, wrong target, mis-measured distance, half a tank when spec says full - it will still say complete and the customer will still get an AEB false brake. Any answer choice that treats 'calibration passed' as proof of correct aim is bait.
• Assuming the DTC names the failed part. 'Radar sensor performance' or 'camera blocked' points at a condition, not a component. Techs swap a $900 radar when the real cause is Bondo behind the fascia, a mismatched tire, or a bent bracket from a low-speed hit. On L4, look for the mechanical/collision-repair root cause hiding behind an electrical-sounding code.
• Confusing centerline with thrust line, and confusing LDW/LKA/LCA/BSM. Look-alike answers deliberately swap warning-only features with intervening features, or swap 'measure from the vehicle centerline' into an otherwise correct procedure. Read every distractor for that one swapped word.
• Skipping the pre-scan. Techs assume a system is fine because no lamp is on, then find stored codes after calibration and cannot prove they did not cause them. The exam expects pre-scan, repair, calibrate, post-scan, road-test verify, and documentation - in that order, every time.

A study plan that works for L4

Roughly two weeks of real preparation, in the order that actually builds on itself.

1. Days 1-3: Nail the fundamentals cold. SAE J3016 levels 0-5, J3063 naming, and what each sensor type can and cannot physically see (radar = closing speed, poor lateral resolution; camera = classification and lane lines, blind in glare/fog; ultrasonic = short range only; lidar = point cloud, weather-sensitive). Do not move on until you can pick the right sensor for a described failure without guessing.
2. Days 4-8: Live in the calibration procedures. Pull two or three real OEM procedures (a Toyota static, a Honda dynamic, a GM/Ford hybrid) and read them line by line. Write down every prerequisite and every measurement reference. Then go do one in the bay if you can - measuring target distance off the thrust line once teaches more than ten hours of reading.
3. Days 9-12: Wire and network work. Practice diagnosing loss-of-communication on CAN FD and automotive Ethernet, SAS zero-point relearns, and IMU/yaw sensor faults. Drill the ADAS-adjacent A4 material too - thrust angle, ride height, tire size mismatch - because it carries real weight here.
4. Days 13-14: Practice tests only, and audit your misses. For every wrong answer, write one sentence on WHY the distractor looked right. That habit is what beats the look-alike answers on test day.

Sample L4 questions

Straight from the bank — answers highlighted, with the explanation underneath.