Electric Motor Inspection

Comprehensive inspection of front and rear electric drive motors including visual inspection, electrical testing, bearing condition assessment, and cooling system verification on the 2025 Rivian EDV 500 Dual Motor AWD system.

Warnings

Tools required

Parts

• Motor coolant line O-rings × 4 — Use OEM specification
• High voltage connector seals × 2 — Use OEM specification
• Motor mounting hardware × 1 — Use OEM specification if damaged

Fluids

• EV Battery/Motor Coolant — 10 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure vehicle has been off for minimum 2 hours to allow high voltage system and cooling system to depressurize and cool
3. Remove key fob from vehicle and place in Faraday pouch to prevent remote activation
4. Connect Rivian diagnostic software and document any existing fault codes related to drive motors
5. Access HV disconnect location under rear cargo area and follow manufacturer lockout/tagout procedure
6. Verify HV system de-energized using diagnostic software - confirm battery contactors open
7. Wait 15 minutes minimum for high voltage capacitor discharge
8. Disconnect 12V auxiliary battery negative terminal
9. Lift vehicle on hoist to access height, ensuring proper lift point contact per manufacturer specifications
10. Remove front and rear underbody shields to access motor assemblies
11. Place warning tags on steering wheel indicating HV system service in progress

Procedure

1. 1

   Initial Visual Inspection - Rear Motor
   Inspect rear motor assembly for external damage, fluid leaks, and mounting condition. Check for signs of coolant weeping around motor housing seams, bearing oil leaks, and physical impact damage. Inspect motor mounting bolts for tightness and corrosion. Examine all electrical connectors for corrosion, melting, or discoloration indicating overheating. Check coolant hoses for cracks, swelling, or leakage at connection points.
2. 2

   Initial Visual Inspection - Front Motor
   Repeat visual inspection for front motor assembly. Pay particular attention to mounting hardware as front motor experiences different loading during acceleration. Inspect drive unit housing for cracks or damage. Check differential breather for contamination that might indicate seal failure allowing water intrusion.
3. 3

   High Voltage Connector Inspection
   Wearing HV insulated gloves, carefully inspect high voltage power cables and connectors to both motors. Check orange HV cables for chafing, cuts, or damage to insulation. Inspect connector housings for cracks and proper seating. Check interlock circuits are intact. Look for discoloration or melting indicating poor connection or arcing. Document condition with photos if any abnormalities found.
4. 4

   Motor Coolant System Inspection
   Inspect motor cooling system routing and condition. Check coolant level in expansion tank and verify coolant is clean pink/red color without contamination. Inspect coolant pump operation using diagnostic software (no flow test with HV disabled). Check all coolant line connections to motor housings for seepage. Feel coolant lines for soft spots indicating deterioration. Verify coolant temperature sensors are properly connected.
5. 5

   Drain Motor Coolant Circuits
   Position drain pan under rear motor coolant drain point. Open drain valve and drain rear motor cooling circuit completely (approximately 5 quarts). Move drain pan to front motor and repeat process. Inspect drained coolant for metal particles, oil contamination, or discoloration. Presence of metallic debris indicates bearing wear or internal component failure requiring motor replacement.
6. 6

   Motor Bearing Play Assessment
   With coolant drained and motor accessible, manually rotate each motor output shaft to check for binding or unusual resistance. Check for axial and radial play in motor shaft bearings. Normal play should be less than 0.020 inches radially. Excessive play, grinding sensation, or rough rotation indicates bearing failure. Use dial indicator if available for precise measurement. Listen for any abnormal sounds during rotation.
7. 7

   Electrical Insulation Resistance Testing
   Using megohmmeter, perform insulation resistance test on each motor winding to ground. Test between each motor phase terminal and motor housing (ground). Minimum acceptable insulation resistance is 500 megohms at 500V DC test voltage. Connect positive megohmmeter lead to motor phase terminal and negative to motor housing. Perform test on all three phases of each motor. Record all readings. Any reading below 100 megohms indicates moisture intrusion or insulation breakdown requiring motor replacement.
8. 8

   Motor Winding Resistance Testing
   Using precision multimeter, measure resistance between motor phase terminals to verify balanced windings. Measure resistance between Phase A-B, B-C, and C-A on each motor. Readings should be within 5% of each other (typically 0.01-0.05 ohms depending on motor design). Significant imbalance indicates shorted or open windings. Record all measurements and compare to manufacturer specifications in service information.
9. 9

   Rotor Position Sensor Inspection
   Inspect motor resolver or encoder used for rotor position sensing. Check connector for corrosion and proper seating. Using diagnostic software, verify resolver signal quality while manually rotating motor shaft slowly. Signal should show smooth sine/cosine waveforms without dropout or noise. Test resolver resistance according to service specifications. Faulty position sensor causes reduced power, vibration, and fault codes.
10. 10

    Motor Temperature Sensor Verification
    Locate and inspect motor temperature sensors (typically RTD or thermistor type). Verify connector condition and proper seating. Measure sensor resistance at ambient temperature and compare to specification (typically 10k ohms at 77°F for thermistor type). Using diagnostic software, verify temperature readings are reasonable and match ambient conditions. Faulty temperature sensors cause false overtemp shutdowns.
11. 11

    Internal Inspection (if accessible)
    If motor design allows and inspection ports are present, use borescope to inspect internal motor condition. Look for bearing condition, winding insulation condition, and any signs of arcing or contamination. Check for coolant intrusion into motor housing. Inspect rotor surface for scoring or damage. Document findings with photos. This step may require partial disassembly on some motor designs.
12. 12

    Cooling System Pressure Test
    Connect cooling system pressure tester to motor coolant circuit. Pressurize system to 15 PSI and hold for 10 minutes. Monitor for pressure drop indicating leaks. Inspect all motor coolant connections, housing seams, and hoses while under pressure. Mark any leak locations. System should hold pressure with less than 1 PSI drop over 10 minutes. Identify and replace any leaking seals or O-rings.
13. 13

    Refill Motor Coolant System
    Install new O-rings on all motor coolant connections that were disturbed. Refill motor cooling system with specified EV Battery/Motor Coolant through expansion tank. Use coolant system vacuum fill tool if available to eliminate air pockets. Fill to proper level marking on expansion tank. Ensure both front and rear motor circuits are completely filled. Total system capacity is approximately 10 quarts.
14. 14

    Diagnostic Data Analysis
    Using Rivian diagnostic software, review historical data for both drive motors. Check peak temperature recordings, current draw patterns, fault code history, and operating time. Review motor performance degradation data if available. Compare left and right motor performance parameters for symmetry. Export data for documentation. Any asymmetry or abnormal patterns warrant further investigation or component replacement.
15. 15

    Documentation and System Preparation
    Document all inspection findings including test measurements, visual observations, and any components requiring replacement. Clean all motor external surfaces and electrical connectors with appropriate non-conductive cleaner. Apply dielectric grease to HV connectors if permitted by manufacturer. Install underbody shields. Reconnect 12V battery. Remove lockout/tagout devices from HV system. Clear any inspection-related diagnostic codes. Update vehicle service records with inspection results.

Reassembly

1. Ensure all coolant line connections are properly torqued and new O-rings are installed on any disturbed connections
2. Verify all high voltage connectors are fully seated with interlock circuits connected and latches engaged
3. Reinstall front and rear underbody shields with all fasteners properly secured
4. Reconnect 12V auxiliary battery negative terminal
5. Verify all service tools and equipment are removed from vehicle and surrounding area

Verification

• Connect Rivian diagnostic software and energize high voltage system following manufacturer procedure
• Verify no new fault codes present related to drive motors or power electronics
• Using diagnostic software, command each motor to perform self-test routine if available
• Perform motor coolant bleed procedure using diagnostic software to remove any remaining air from system
• Verify coolant level is at proper mark after bleeding and top off if necessary
• With vehicle on lift, briefly command motor rotation in both directions to verify proper operation without abnormal sounds (wheels will rotate)
• Lower vehicle and perform test drive at various speeds and loads, monitoring motor temperatures, current draw, and performance using diagnostic software
• Verify both motors provide balanced torque output and no vibrations or abnormal sounds are present during acceleration and regenerative braking
• Check for coolant leaks after test drive with system at operating temperature
• Final diagnostic scan to confirm no fault codes and all motor systems operating within normal parameters
• Document final inspection results including all test measurements and verification test outcomes in vehicle service history

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle