Hybrid & EV Service Technician Certification Exam
Verified Questions and
(Tesla + ASE L3 style)
Answers | 2026 Version | Latest Update
1.
A technician begins servicing a high-voltage EV battery pack. What is the first required safety
step?
A. Disconnect the 12-volt auxiliary battery
B. Remove the high-voltage service disconnect
C. Turn off the ignition key
D. Disconnect the inverter
Correct Answer: A
Rationale:
The 12-volt system controls contactors that connect the high-voltage battery. Disconnecting it
prevents the system from energizing unexpectedly.
2.
An EV sets a diagnostic code indicating high voltage isolation fault. What is the most likely
cause?
A. Moisture intrusion in the high-voltage system
B. Faulty oxygen sensor
C. Incorrect tire pressure
D. Low coolant level in radiator
Correct Answer: A
,Rationale:
Isolation faults occur when high-voltage components leak current to chassis ground, often
due to moisture or damaged insulation.
3.
A hybrid vehicle experiences reduced regenerative braking performance. What system should
be inspected first?
A. Battery state-of-charge and temperature
B. Spark plugs
C. Exhaust system
D. Engine oil pressure
Correct Answer: A
Rationale:
Regenerative braking efficiency depends on battery charge acceptance and thermal
conditions.
4.
A technician measures DC battery voltage at 400V but inverter output is unstable. What
component is most likely failing?
A. Inverter power module
B. Oxygen sensor
C. Fuel pump
D. Exhaust gas recirculation valve
Correct Answer: A
Rationale:
The inverter converts DC battery voltage into three-phase AC for the electric drive motor.
Failure leads to unstable motor operation.
,5.
A hybrid vehicle displays “High Voltage System Shutdown” while driving. What system most
likely triggered the shutdown?
A. Battery management system protection
B. Fuel injection system
C. Cooling fan relay
D. Catalytic converter
Correct Answer: A
Rationale:
The BMS monitors battery temperature, voltage, and current. Dangerous conditions cause
automatic high-voltage shutdown.
6.
An EV battery pack shows significant voltage imbalance between modules. What condition is
likely present?
A. Cell degradation or imbalance
B. Faulty spark plug
C. Weak alternator
D. Low engine oil
Correct Answer: A
Rationale:
Module imbalance indicates uneven aging or failing battery cells, which the BMS may attempt
to balance.
7.
A hybrid vehicle fails to enter electric-only mode even with adequate battery charge. What
component should be inspected?
, A. Hybrid control module
B. Catalytic converter
C. Fuel injector
D. Crankshaft sensor
Correct Answer: A
Rationale:
The hybrid control module determines when the vehicle operates in EV mode or hybrid
mode.
8.
A technician detects excessive heat within the battery pack during charging. What system
should be inspected?
A. Battery thermal management system
B. Exhaust manifold
C. Transmission cooler
D. Intake air filter
Correct Answer: A
Rationale:
EV batteries require controlled cooling systems (liquid or air) to maintain safe operating
temperatures.
9.
An EV exhibits reduced driving range despite normal battery capacity readings. What
system should be inspected?
A. Regenerative braking operation
B. Fuel pump
C. Spark plug gap
D. Oxygen sensor
Correct Answer: A
Verified Questions and
(Tesla + ASE L3 style)
Answers | 2026 Version | Latest Update
1.
A technician begins servicing a high-voltage EV battery pack. What is the first required safety
step?
A. Disconnect the 12-volt auxiliary battery
B. Remove the high-voltage service disconnect
C. Turn off the ignition key
D. Disconnect the inverter
Correct Answer: A
Rationale:
The 12-volt system controls contactors that connect the high-voltage battery. Disconnecting it
prevents the system from energizing unexpectedly.
2.
An EV sets a diagnostic code indicating high voltage isolation fault. What is the most likely
cause?
A. Moisture intrusion in the high-voltage system
B. Faulty oxygen sensor
C. Incorrect tire pressure
D. Low coolant level in radiator
Correct Answer: A
,Rationale:
Isolation faults occur when high-voltage components leak current to chassis ground, often
due to moisture or damaged insulation.
3.
A hybrid vehicle experiences reduced regenerative braking performance. What system should
be inspected first?
A. Battery state-of-charge and temperature
B. Spark plugs
C. Exhaust system
D. Engine oil pressure
Correct Answer: A
Rationale:
Regenerative braking efficiency depends on battery charge acceptance and thermal
conditions.
4.
A technician measures DC battery voltage at 400V but inverter output is unstable. What
component is most likely failing?
A. Inverter power module
B. Oxygen sensor
C. Fuel pump
D. Exhaust gas recirculation valve
Correct Answer: A
Rationale:
The inverter converts DC battery voltage into three-phase AC for the electric drive motor.
Failure leads to unstable motor operation.
,5.
A hybrid vehicle displays “High Voltage System Shutdown” while driving. What system most
likely triggered the shutdown?
A. Battery management system protection
B. Fuel injection system
C. Cooling fan relay
D. Catalytic converter
Correct Answer: A
Rationale:
The BMS monitors battery temperature, voltage, and current. Dangerous conditions cause
automatic high-voltage shutdown.
6.
An EV battery pack shows significant voltage imbalance between modules. What condition is
likely present?
A. Cell degradation or imbalance
B. Faulty spark plug
C. Weak alternator
D. Low engine oil
Correct Answer: A
Rationale:
Module imbalance indicates uneven aging or failing battery cells, which the BMS may attempt
to balance.
7.
A hybrid vehicle fails to enter electric-only mode even with adequate battery charge. What
component should be inspected?
, A. Hybrid control module
B. Catalytic converter
C. Fuel injector
D. Crankshaft sensor
Correct Answer: A
Rationale:
The hybrid control module determines when the vehicle operates in EV mode or hybrid
mode.
8.
A technician detects excessive heat within the battery pack during charging. What system
should be inspected?
A. Battery thermal management system
B. Exhaust manifold
C. Transmission cooler
D. Intake air filter
Correct Answer: A
Rationale:
EV batteries require controlled cooling systems (liquid or air) to maintain safe operating
temperatures.
9.
An EV exhibits reduced driving range despite normal battery capacity readings. What
system should be inspected?
A. Regenerative braking operation
B. Fuel pump
C. Spark plug gap
D. Oxygen sensor
Correct Answer: A
