📘 Electric Vehicle (EV) – Complete Repair Glossary
Electric Vehicle (EV) — any vehicle that uses one or more electric traction motors powered by rechargeable battery packs. This glossary covers BEV, PHEV, HEV components with real-world diagnosis, symptoms, and repair costs.
HV battery
Traction motor
Inverter
OBC
TMS
DC-DC
🔋 HV Battery & BMS (Battery Management System)
Core function: Stores DC energy, manages cell balancing, monitors temperature, SOC, SOH.
Common issues & symptoms
- Cell imbalance: reduced range, early charging termination, DTCs P0Bxx.
- BMS communication fault: no start, turtle mode, inaccurate range guess.
- Internal short / swollen cells: odor, pack deformation, extreme temp.
🔍 Diagnostic steps (multiple options)
- ✅ Perform insulation test (megger) between HV+/HV- and chassis – target >500kΩ.
- ✅ Use EV scan tool (Autel, Launch, Tesla Toolbox) to read min/max cell voltage delta – critical if >50mV.
- ✅ Battery capacity test: full discharge/charge with diagnostic equipment (actual kWh vs rated).
- ✅ Thermal imaging during fast charge to spot uneven heating.
- ✅ Coolant inspection – if liquid cooled, check for conductive fluid contamination.
| Repair type | Parts cost | Labor | Total (estimate) |
|---|---|---|---|
| Single module replacement | $900 – 2,400 | $350 – 700 | $1,250 – 3,100 |
| BMS board / slave repair | $400 – 950 | $200 – 500 | $600 – 1,450 |
| Complete pack replacement | $7,000 – 22,000+ | $1,000 – 2,200 | $8,000 – 24k+ |
⚙️ Traction Motor (AC induction / PMSM)
Symptoms & Diagnosis
- 🔹 Whining/grinding noise – worn bearings or magnet damage.
- 🔹 Reduced power / shudder – resolver failure or phase short.
- 🔹 Overheat – winding insulation breakdown.
📋 Diagnostics
- 🔸 Measure insulation resistance phase-to-phase, phase-to-ground (min 1MΩ @500V).
- 🔸 Check resolver signals with oscilloscope; verify 5V excitation.
- 🔸 Inverter output waveform capture – clean sine?
- 🔸 Bearing noise check via chassis ears.
Motor replacement: $2,200 – 5,800 Rotor/refurb: $1,200 – 2,800
⚡ Inverter / Power Electronics
- Issues: IGBT failure, capacitor aging, gate drive fault.
- → sudden loss of drive, error “powertrain fault”.
| Diagnostic | Tool | Cost range repair |
|---|---|---|
| DC bus voltage test | HV DMM | Inverter exchange $1,900 – 3,800 |
| Phase current sensor calibration | EV scan / scope |
🔌 Onboard Charger & AC-DC
Converts AC to DC. Failure → cannot charge AC, but DC fast charge works.
🛠️ Step-by-step diagnosis
- Verify pilot signal (CP) from EVSE – PWM duty cycle correct? (use oscilloscope).
- Measure AC input at charger terminals – missing voltage?
- Check 12V standby power to OBC.
- Inspect charger coolant (if liquid cooled) for flow.
- Communicate via CAN – read fault codes: P0C4E, P3006 etc.
OBC replacement: $1,100 – 2,600 Refurb: $600 – 1,200
🔽 DC-DC Converter
- ⚠️ 12V battery not charging, flickering lights, frequent jump starts.
- 📊 Check output voltage at converter: should be 13.5V – 14.8V.
- 💲 replace $700 – 1,600, diagnosis 0.5h
🔌 Charging Inlet & HV Cabling
| Issue | Symptom | Diagnosis | Repair cost |
|---|---|---|---|
| Melted pins | Charging stops, error | visual, thermography | $300 – 800 |
| Lock actuator fail | Can’t remove plug | 12V at actuator? | $150 – 400 |
🌡️ Thermal system / Battery chiller
- Slow charging in cold, reduced regen → coolant pump failure, air in system.
- Diagnose: scan coolant temp sensors, heater PTC resistance, electric water pump operation.
- Repair: pump $300-700, heater $600-1400
🔁 Regen Brake & Blended system
Symptoms: no regen, brake pedal feel odd, reduced range.
⚙️ Multi‑option diagnosis
- Brake pedal travel sensor (Hall effect) – voltage curve.
- Check wheel speed sensors & ABS module comm.
- BMS request: if battery cold or full, regen inhibited (normal).
- HV contactor stuck? regen disabled.
🧲 HV contactors & precharge circuit
- Clicking but no power – precharge resistor failed.
- Measure precharge voltage rise via oscilloscope (DC bus).
- Contactors: $400 – 900 each + labor.
🔋 12V auxiliary battery
Dead 12V = entire EV dead . Symptoms: no dashboard, contactor won’t close.
Diagnosis: load test, DC-DC wake-up signal. Cost: $150 – 350 (AGM/Li-ion).
🛑 EV-specific DTC library
| Code | Description | Likely component |
|---|---|---|
| P0AA6 | HV battery isolation loss | Insulation failure |
| P1E00 | Drive motor inverter performance | Inverter IGBT |
| P0C78 | Battery pack voltage out of range | Cell group |
| U029D | Lost communication with OBC | CAN / charger |
🛡️ HV Safety mandatory
Class 0 gloves (1kV)
Insulation tester
Lockout/tagout
HV multimeter CAT III
💰 Full EV repair cost benchmark
| Component | Typical parts (USD) | Labor | Total range |
|---|---|---|---|
| HV battery module | $1,200 – 2,800 | $400 – 900 | $1,600 – 3,700 |
| Traction motor | $1,900 – 4,800 | $700 – 1,500 | $2,600 – 6,300 |
| Inverter | $1,600 – 3,200 | $500 – 1,100 | $2,100 – 4,300 |
| Onboard charger | $800 – 2,200 | $300 – 700 | $1,100 – 2,900 |
| DC-DC converter | $550 – 1,300 | $200 – 500 | $750 – 1,800 |
🧰 EV long-life tips
Keep 20-80% daily
Precondition battery
Tire rotation 6k mi
Brake flush /2yr
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