Diagnostics & Repair Procedures Flashcards
7 cards from real EVT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Diagnostics & Repair Procedures flashcards as text
During an EV high-voltage system repair, a technician notices an orange cable running along the vehicle frame. What does this cable indicate?
Answer: High-voltage traction system wiring
Orange cables are the industry-standard color coding for high-voltage traction system wiring in electric and hybrid vehicles.
What does a 'negative temperature coefficient' (NTC) thermistor reading that is significantly lower than ambient temperature indicate in a battery thermal sensor circuit?
Answer: An open circuit or disconnected sensor
An NTC thermistor resistance rises as temperature drops; a reading far below ambient typically indicates an open circuit rather than extreme cooling.
When replacing an EV traction motor, which additional component should always be inspected or replaced due to shared operational stress?
Answer: The inverter/motor controller and its gate drive circuitry
The inverter drives the motor directly; a motor failure caused by an electrical fault can damage the inverter's IGBTs or gate drivers, and vice versa.
An EV fails to power on and shows no 12V supply to the main control modules. The HV battery SOC is adequate. What is the MOST likely cause?
Answer: Failed DC-DC converter
The DC-DC converter steps down HV to 12V to power vehicle control modules; its failure would cut 12V supply and prevent the vehicle from powering on.
A scan tool shows the main positive contactor closes but the precharge contactor code remains active. What is the MOST likely fault?
Answer: Failed precharge resistor or precharge contactor
The precharge circuit uses a resistor and contactor to slowly charge the inverter bus capacitors; a failure in either component will set a precharge fault.
When using a bi-directional scan tool to actuate HV contactors for testing, what safety precaution is CRITICAL?
Answer: Confirm no HV cables are disconnected and all safety shields are installed
Actuating contactors with HV cables disconnected or shields removed exposes personnel to lethal voltage arcing when the contactors close.
An EV produces a grinding noise during regenerative braking at low speeds only. What is the MOST likely cause?
Answer: Brake caliper dragging due to incomplete pad retraction after blended braking
Blended braking systems combine regen with friction brakes; if calipers don't fully retract after regen phases, they can drag and grind at low speeds.