2026 Edition

ASE L3 Practice Test

Take this free ASE L3 Practice Test to study for your ASE L3 certification exam.

The National Institute for Automotive Service Excellence (ASE) identifies Light Duty Hybrid / Electric Vehicle Specialist as an individual service area for certification (L3). The following subjects are covered:

• Battery Systems
• Internal Combustion Engines
• Drive Systems
• Power Electronics
• Hybrid Supporting Systems

There are 55 questions on the exam, 45 of which are scored, and 2 hours is given to complete it.

To prepare for the ASE L3 exam, use Tests.com's ASE L3 Practice Test. It is written by Dr. John Kershaw, an ASE test question developer and ASE Certified Master Technician. Our interactive test platform allows you to simulate the exam. Take as many practice tests as you need. There's no time limit or recurrent charges.

To qualifty to take the L3 exam, you must have passed the A6 and A8 exams. To prepare for the ASE A6 exam, use our ASE A6 Practice Test. To prepare for the A8 exam, use our ASE A8 Practice Test.

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Battery System

1 Which of the following is least likely to cause a problem in electric vehicle supply equipment (EVSE)?

a. Loose or improperly mated connector

b. Wires with nicks or lumps in the insulation

c. Distorted electrical connector or wire

d. Ground wires connected to unpainted frame surface

Incorrect. Please choose another answer.

Ground wires attached to an unpainted frame surface make a positive contact and unless they become loose are least likely to cause a problem.

A is wrong because a loose or improperly mated connector can present a problem to the circuit and is a likely cause. B is wrong because wires that are nicked are exposed to the elements and will likely start to corrode. As the corrosion forces the insulation to expand, a lump will form in the wire. C is wrong because distorted electrical connector or wire is exposed to the elements and can likely become corroded. Electrical contact points and wires that have been overheated break down at the molecular level and corrosion starts within fractures in the structure.

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2 Using a DMM (Digital Multimeter), on a fully charged 12-volt hybrid electric vehicle auxiliary battery, how much voltage should the open circuit voltage (OCV) test show?

a. 11.6 volts

b. 4 volts per cell

c. 12.6 volts

d. 1 volt per cell

Incorrect. Please choose another answer.

The standard is 2.1 volts per cell and 2.1 times 6 is 12.6 volts. The other choices are incorrect on a fully charged auxiliary battery. Battery voltage needed to start the ICE engine is going to be over 12 volts, ideally would be 12.6 volts. When you crank the engine, the starter will draw current and drop the over 12v to 10.6 volts. During starting a healthy car battery voltage should be 10v or higher. Cold weather needs to be considered as this will decrease the voltage and increase the amount of power to turn over a cold engine. The voltage, when the engine is running, should be in the range of 13.5-14.7 volts.

Internal Combustion Engine

3 The internal combustion engine on an older Ford hybrid electric vehicle will still not crank after a minor front collision and there is a stored diagnostic trouble code B2171 Inertia Input Switch Circuit open with no messages shown. Which of the following could be the cause?

a. Defective ignition module

b. Tripped inertia cutout switch

c. Inverter overheated

d. Battery at 11.6 volts

Incorrect. Please choose another answer.

A not start condition along with a stored DTC B2171 Inertia Input Switch Circuit open will take place after a frontal collision because the inertia cutout switch will trip in a collision. This is similar to Ford's inertia fuel cutout switch. A is incorrect because the engine will not crank and there is no ignition needed yet. C is incorrect because if the inverter were overheated there would be a message Stop Safely Now. D is incorrect because when you crank the engine the starter will draw current and drop to 10.6 volts and should still crank but may be slow. During starting a healthy car battery voltage should be 10v or higher.

4 A plug-in hybrid electric vehicle will enter the POWER ON (Key On Engine Off) mode, but will not go into the READY TO DRIVE (Key On Engine Running) mode. There is no diagnostic trouble code in history or active. Which of the following could be the cause?

a. Failed brake on/off switch

b. High voltage safety plug is removed

c. ICE fuel tank empty

d. Disconnected 12-volt auxiliary battery

Incorrect. Please choose another answer.

When the brake on/off switch is defective, the vehicle would enter the POWER ON (Key On Engine Off) mode. Yet a failed brake on/off switch would not allow the hybrid engine control unit (ECU) to confirm that the brake pedal is applied, which is necessary for entering the READY TO DRIVE (Key On Engine Running) mode. It is possible that the ECU may not yet have recognized the lack of a feedback signal from the failed switch so a diagnostic trouble code (DTC) may not yet be stored.

B is wrong because when the high voltage safety plug is removed, the vehicle will enter the POWER ON (Key On Engine Off) mode, but would not enter the READY TO DRIVE (Key On Engine Running) mode. Also, with the safety plug removed the hybrid electric vehicle will store the DTC. C is wrong because with an empty fuel tank, the vehicle would enter the POWER ON (KOEO) mode and the READY TO DRIVE (KOER) modes as long as the high voltage battery maintains a sufficient state-of-charge. However, the internal combustion engine (ICE) would crank, but would not start due to the lack of fuel in the tank. This condition would set a DTC because the ICE did not start. D is wrong because a disconnected 12-volt auxiliary battery would prevent the vehicle from entering any operational power mode since the HEV ECU would not power up.

Drive System

5 Technician A says you can use a digital multimeter (DMM) to check the resistance between negative and ground while cranking the starter. Technician B says to check the voltage drop between (+) positive and the starter terminal stud while the starter is cranking. Who is right?

a. A only

b. B only

c. Both A and B

d. Neither A nor B

Incorrect. Please choose another answer.

Technician B is right because checking the voltage drop between (+) positive and the starter terminal stud while the starter is cranking is a voltage drop check on cable connection resistance. Technician A is wrong because this will overload the fuse and could cause damage to the ohmmeter section of the DMM. The technician should use the voltmeter function of the DMM.

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6 Two technicians are explaining the use of high voltage rubber gloves when servicing hybrid electric vehicles or plug-in hybrid electric vehicles. Technician A says that you must be sure that the gloves are rated at least 500 volts and class "1" by American National Standards Institute/American Society for Testing Materials (ANSI/ASTM). Technician B says that leather gloves should be worn over the high-voltage rubber gloves to protect the rubber gloves from damage. Who is right?

a. A only

b. B only

c. Both A and B

d. Neither A nor B

Incorrect. Please choose another answer.

Technician B is correct because leather gloves should be worn over the high-voltage rubber gloves to protect the rubber gloves from damage from sharp objects. Technician A is incorrect because the gloves should be rated at least 1000 volts not 500 volts and class "0" by ANSI/ASTM.

Power Electronics

7 What color plastic conduit identifies 144 to 600 voltage cables in hybrid electric vehicles and plug-in hybrid electric vehicles?

a. Blue

b. Red

c. Yellow

d. Orange

Incorrect. Please choose another answer.

High-voltage cables are identified by color of the plastic conduit and orange is used for 144 to 600 volts or higher. Blue or yellow are used for 42 volts, which are not a shock hazard but an arc will be maintained if a circuit is opened. Red is used for 12-volt circuits.

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8 Two technicians are describing the AUTO STOP feature on a Plug-In Hybrid Electric Vehicle (PHEV). Technician A says that the PHEV shuts down the internal combustion engine (ICE) whenever the vehicle stops if the AUTO STOP criteria has been met. Technician B says the PHEV can come to a complete a full stop without any driver input. Who is right?

a. A only

b. B only

c. Both A and B

d. Neither A nor B

Incorrect. Please choose another answer.

Technician A is correct because the PHEV shuts down the ICE whenever the vehicle comes to a full and complete stop when the AUTO STOP criteria has been met and vehicle should be silent in the electric operation mode. Tech B is incorrect because some driver input is required; such as: driver's seat belt is not buckled, driver's door is not closed, vehicle is on a steep grade, HVAC is set to full defrost mode at a high blower speed, HVAC set to MAX A/C, transmission is not in a forward gear, hood is open, or brake pedal is not pressed with sufficient pressure.

Hybrid Supporting Systems

9 To answer questions 9 and 10, refer to the ASE L3 reference document using this link in a new tab: https://www.ase.com/uploads/L3Studyguide2021_210112_141628.pdf

A Type-2 hybrid vehicle without an auxiliary starter will enter READY TO DRIVE (KOER) mode but will not crank the internal combustion engine (ICE). Which of the following could be the cause?

a. Depleted high voltage battery

b. Failed MG2

c. Failed crankshaft position sensor

d. Failed MG

Incorrect. Please choose another answer.

The MG serves as the starter motor for the ICE. Some Type-2 vehicles may be equipped with an auxiliary 12 V starter motor but the stem states that this vehicle does not have one. Power flow to the drive wheels can be provided by a split-pulley/steel belt continuously variable transmission, a conventional automatic transmission, or a standard transmission. A is incorrect because vehicle will enter READY TO DRIVE (KOER) mode, so voltage is available Equivalent to KOER - Key On/Engine Running. In this mode, the vehicle is ready to drive. The engine is running, or is OFF and ready to run if so commanded. The electric drive system is also ready for a drive command. B is incorrect because a Type-2 HEV does not use an MG1 or MG2 only an MG. C is incorrect because the CKP (crankshaft position) sensor is not need to crank the engine.

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10 On a Type-3 hybrid vehicle, the high-voltage battery pack falls to a predetermined state-of-charge, but the internal combustion engine (ICE) fails to start and it is in the READY TO DRIVE (KOER) mode. Which of the following is the most likely cause?

a. Depleted high voltage battery

b. Seized MG1

c. Failed crankshaft position sensor

d. Failed MG

Incorrect. Please choose another answer.

The MG1 serves as the starter motor for the ICE. A is incorrect because the vehicle will enter READY TO DRIVE (KOER) mode, so voltage is available Equivalent to KOER - Key On/Engine Running. In this mode, the vehicle is ready to drive. The engine is running, or is OFF and ready to run if so commanded. The electric drive system is also ready for a drive command. C is incorrect because the CKP (crankshaft position) sensor is not need to crank the engine. D is incorrect because a Type-3 HEV uses both an MG1 & MG2.