EVT Diagnostics & Repair Procedures 4

Question 1

A technician is diagnosing intermittent HV system faults that only appear after extended driving. What is the BEST diagnostic approach?

Accepted Answer

Perform a thermal soak test and monitor data PIDs during and after heat buildup

Answer

Thermal soak testing exposes temperature-sensitive faults in connectors, sensors, or components that only appear when the system reaches operating temperature.

Question 2

What is the function of the pyrotechnic safety switch (PSS) found in some EV battery packs?

Accepted Answer

It disconnects HV circuits in milliseconds during a severe crash event

Answer

A pyrotechnic safety switch uses a small explosive charge to physically sever the HV circuit almost instantaneously during a crash, preventing electrocution or fire.

Question 3

After replacing a high-voltage battery module, what procedure must be completed to ensure proper BMS operation?

Accepted Answer

Execute a battery module configuration or initialization procedure via scan tool

Answer

The BMS must be reconfigured or initialized to recognize the new module's cell chemistry, capacity, and serial data to manage it correctly.

Question 4

When testing the insulation of an EV HV cable harness, what voltage should the insulation tester (megohmmeter) apply to avoid damaging the cable insulation?

Accepted Answer

A voltage level appropriate for the cable's rated voltage class, per manufacturer specification

Answer

Test voltage must be selected based on the cable's rated voltage class; using too high a test voltage can damage the insulation being tested.

Question 5

An EV's thermal management system shows the battery coolant temperature rising rapidly during DC fast charging. The coolant pump is confirmed operational. What is the NEXT component to check?

Accepted Answer

The battery chiller (heat exchanger) and refrigerant charge in the thermal circuit

Answer

If the pump is working but temperature still rises, the battery chiller or refrigerant circuit is likely not removing heat effectively from the coolant loop.

(EVT) Certified Electric Vehicle Technician Practice Test

(EVT) Certified Electric Vehicle Technician Practice Test

EVT Diagnostics & Repair Procedures 4