2026 Edition

ASE L4 Practice Test

Take this free ASE L4 Practice Test to study for your ASE L4 certification exam for Advanced Driver Assistance Systems (ADAS). Our ASE L4 test prep is written by an ASE Certified Master Technician and ASE question developer. To prepare for the ASE L4 exam, use our 100 question ASE L4 Practice Test.

To qualify to take the L4 exam, you must have passed the A6 or B5 exams. To prepare for the ASE A6 exam, use our ASE A6 Practice Test.

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General ADAS Service and Diagnosis

1 Technician A says performing a pre-scan of the OBD-II system for trouble codes should be done before performing repair or calibration on an ADAS equipped vehicle. Technician B says performing a post-scan is a best-practice to verify repair and calibration are successful. Who is right?

a. A only

b. B only

c. Both A and B

d. Neither A nor B

Incorrect. Please choose another answer.

Both technicians are correct. Tech A is correct because you need to check all control modules for diagnostic information before disconnecting the vehicle battery as information kept in keep-alive memory may be lost when power to the control modules is removed. The loss of this data could be costly after the repair, could delay repairs and could be dangerous if the vehicle is returned to the customer with a malfunctioning ADAS system. A pre-scan of the vehicle systems should be performed with a factory scan tool or equivalent OBD-II CAN aftermarket scan tool. The diagnostic trouble codes retrieved should be recorded on the RO. Tech B is correct because verifying the repair is part of a sound diagnostic strategy.

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2 Technician A says a road test of a vehicle is not needed if an ADAS calibration is successful. Technician B says a road test should be performed at the end of each ADAS repair or calibration to verify the calibration or system functionality. Who is right?

a. A only

b. B only

c. Both A and B

d. Neither A nor B

Incorrect. Please choose another answer.

Tech B is correct because it is an industry best practice to verify that the ADAS system is working properly. You need to drive the vehicle and make sure all ADAS systems are functional and all visual, audible and haptic alerts are working. After the road test, scan all vehicle systems and be sure there are no DTC's for ADAS-related systems.

3 Measurement and layout for an ADAS vehicle calibration begin with consulting the online service information to determine the calibration details. Some OEMs (Original Equipment Manufacturers) will require as much as 20 feet in front of a vehicle with no:

a. Clutter backdrop

b. Scan tool connected

c. DTC Diagnostic Trouble Code) set

d. Inclinometer used

Incorrect. Please choose another answer.

A measurement and layout begin with consulting the online service information to determine the calibration considerations. Some manufacturers will require as much as 20 feet in front of a vehicle with a plain backdrop free of clutter. You will need a roll of masking tape, a marker or pen, and chalk on-hand for marking the floor and an inclinometer will be utilized to make sure the floor is level.

4 For question 4, refer to the ASE L4 reference document using this link in a new tab: https://www.ase.com/dist/docs/ASE_L4_CV1_2022.pdf

All of the following are correct on the ADAS Composite Vehicle 1 Blind Spot Warning (BSW) that detects vehicles in adjacent lanes to the rear and alerts drivers to their presence, EXCEPT:

a. Left and right rear corner radar modules are the primary inputs.

b. System can be turned OFF using the ADAS control panel switch.

c. When the ignition switch is cycled from ON to OFF the System defaults to OFF

d. Parameters can be adjusted using the infotainment display center.

Incorrect. Please choose another answer.

Page 5 of Composite Vehicle 1 states that when the ignition switch is cycled from ON to OFF, the System defaults to ON, not OFF.

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Camera-based Systems Service and Diagnosis

5 Two technicians are discussing ADAS camera calibration. Technician A says that replacing a windshield will require calibration of the multifunction forward-facing camera. Technician B says a battery charger keeps a vehicle's battery charged during the ADAS system calibration. Who is right?

a. A only

b. B only

c. Both A and B

d. Neither A nor B

Incorrect. Please choose another answer.

Tech A is correct because the ADAS system may need to be calibrated after the following service:

Following windshield repair or replacement
After a wheel alignment
After repair or replacement of suspension or steering components
Following collision repair damage
When following a repair procedure or DTC that recommends or requires calibration
When a customer complaint that could be considered a system malfunction is suspected

Tech B is incorrect because a battery maintainer is used to keep a vehicle's battery charged during the ADAS system calibration, not a battery charger. A vehicle with doors or other accessories powered up for more than five minutes may begin to deplete the battery.

6 A driver complains that the brakes seem to release slowly at times, usually when stopped on a hill. This is normal operation of which of the following ADAS systems?

a. Hill start assist

b. Pre-collision

c. Adaptive cruise control

d. Automatic emergency braking

Incorrect. Please choose another answer.

The electronic brake control module (EBCM) calculates the brake pressure that is needed to hold the vehicle on an incline, and locks that pressure for a certain time by commanding the appropriate solenoid valves on and off when the brake pedal is released. Drivers are not aware that the vehicle is equipped with this system. As a result, when the brake pedal is released after being stopped on a hill, the brakes are slow to release. The other three ADAS systems will not do this action.

Radar-based Systems Service and Diagnosis

7 An ADAS Radar unit is being calibrated. Which of the following tools is used to locate the vehicle centerline?

a. Ruler

b. Tape measure

c. Slide rule

d. Plumb bob

Incorrect. Please choose another answer.

You must determine the centerline of the vehicle. A plumb bob is used to find the centerline by locating the center of the emblem in the front and rear of the vehicle and marking the center on the floor at the location of the plumb bob. Then, the vehicle's center line can be projected using a string or a laser level. Choosing an appropriate location to perform ADAS calibrations is vital. The shop should be well-lit with overhead lighting that is even and consistent. The shop floor should be level, as a slope to the floor could lead to improper calibrations.

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8 Calibrating radar involves all of the following, EXCEPT:

a. Factory-level scan tool

b. Special targets set at precisely specified location around the vehicle

c. Both static (stationary) and dynamic (moving) calibration is used

d. Driving the vehicle in a circle 6 times for camera calibration

Incorrect. Please choose another answer.

Driving the vehicle in a circle will not properly locate the corners. Radar or camera calibration on an ADAS vehicle is required when one or more cameras are replaced on a mounting component, such as a windshield, bumper cover, mirror or door. The calibration is a shop static process. Patterned mats are located around the vehicle at specific locations and the scan tool is used to initiate the process. A factory-level scan tool is required on most ADAS dynamic calibration.

9 For questions 9 and 10, refer to the ASE L4 reference document using this link in a new tab: https://www.ase.com/dist/docs/ASE_L4_CV1_2022.pdf

The ADAS Composite Vehicle 1 Forward Radar Module assists in collision mitigation by evaluating closing rates of objects using radar waves to determine the distance to objects in the vehicle's path of travel. It is mounted in a non-adjustable, non-repairable bracket directly to the center of the front grille. Still, the base adjustment is done using adjustment screws on the forward radar module. Which screw provides a horizontal setting?

a. Top Left

b. Top Right

c. Bottom Right

d. Bottom Left

Incorrect. Please choose another answer.

The illustration on page 8 of the Composite Vehicle 1 shows that the top left screw is the horizontal adjustment screw. B is incorrect because the top right screw is a fixed pivot. C is incorrect because the bottom right screw is the vertical adjustment screw. D is incorrect because the bottom left screw is a variable position slot.

Ultrasonic (Sonar)-based Systems Service and Diagnosis

10 What ADAS system Detection Zone does the above pattern represent?

a. Rear Corner Radar

b. Ultrasonic Sensors

c. Multifunction Forward Facing Camera

d. Surround View Camera

Incorrect. Please choose another answer.

As shown on page 17 of the Composite Vehicle 1, ultrasonic sensors have the illustrated patterns. The other three choices are incorrect for the image shown.

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