Electric Motor Inspection

Comprehensive inspection of the electric drive motor assembly, including removal of protective covers, visual inspection of motor housing, bearings, connectors, and associated components to ensure proper operation and identify potential issues.

Warnings

Tools required

Parts

• High-voltage connector seals × 2 — Use OEM specification
• Motor cover gasket × 1 — Use OEM specification
• Thread locking compound × 1 — GM P/N 12345382 or equivalent

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure vehicle has been off for minimum 30 minutes to allow components to cool
3. Disable 12V power by disconnecting negative terminal of 12V auxiliary battery located in rear cargo area
4. Locate high-voltage service disconnect located under rear seat, remove cover and disconnect service plug
5. Wait minimum 10 minutes for high-voltage capacitor discharge
6. Place high-voltage warning tags on steering wheel and service disconnect location
7. Raise vehicle on lift to comfortable working height and secure on lift locks
8. Remove front wheels to access motor assembly area
9. Remove front underbody shields and splash guards for access to motor housing

Procedure

1. 1

   Verify high-voltage de-energization
   Using insulated high-voltage gloves and tools, access the high-voltage junction box near the motor assembly. Using a calibrated high-voltage multimeter, verify zero voltage between HV+ and HV- terminals, and between each terminal and chassis ground. Record voltage readings. Do not proceed if any voltage above 0V DC is detected.
2. 2

   Disconnect high-voltage connectors
   While wearing high-voltage safety gloves, carefully disconnect the orange high-voltage cables from the motor/inverter assembly. Remove the High-Voltage Connector Bolts securing the cables. Inspect connector faces for signs of arcing, discoloration, or corrosion. Cap or cover exposed high-voltage terminals with insulating material.
   ⚠️Even after de-energization, treat all orange cables as live until verified with multimeter at each connection point.
   Torque spec

   Connector Bolts7 Nm (5 lb-ft)
3. 3

   Disconnect low-voltage connectors and sensors
   Disconnect all 12V control connectors from the motor and inverter assembly, including resolver/encoder connectors, temperature sensors, and control module connectors. Remove Sensor Bolts and Connector Bolts as applicable. Label each connector for proper reassembly. Inspect pins for corrosion or damage.
   Torque spec

   Sensor Bolts11 Nm (8 lb-ft)

   Connector Bolts7 Nm (5 lb-ft)
4. 4

   Remove motor protective covers
   Remove the Cover Screws securing the motor inspection covers and protective shields. Carefully remove covers and set aside with hardware. Inspect cover gaskets and seals for deterioration, replacing if compressed or cracked.
   Torque spec

   Cover Screws11 Nm (8 lb-ft)
5. 5

   Remove support brackets
   Remove the Bracket Bolts securing any cable support brackets, harness clips, or auxiliary brackets attached to the motor assembly. Document bracket positions for reassembly.
   Torque spec

   Bracket Bolts20 Nm (15 lb-ft)
6. 6

   Support motor assembly
   Position a suitable transmission jack or motor support fixture under the motor assembly. Raise jack until it just contacts the motor housing to support weight. Do not lift motor at this time.
   ⚠Motor assembly weighs approximately 150 lbs. Ensure support equipment is properly rated and positioned.
7. 7

   Remove motor mounting bolts
   Remove the Motor Mount Bolts and Mounting Bolts securing the motor to the subframe and transaxle housing. Support motor weight with jack while removing final bolts. Note: some mounting bolts may require use of thread locking compound on reassembly.
   ⚠Motor may shift when mounts are released. Maintain firm control with support jack.
   Torque spec

   Motor Mount Bolts75 Nm (55 lb-ft)

   Mounting Bolts27 Nm (20 lb-ft)
8. 8

   Lower and position motor for inspection
   Carefully lower the motor assembly approximately 6-8 inches using the support jack to allow visual and physical inspection access. Do not fully remove motor from vehicle unless complete removal is necessary. Ensure cooling lines and any remaining connections are not strained.
9. 9

   Inspect motor housing and seals
   Visually inspect the motor housing for cracks, impact damage, or signs of fluid contamination. Check all housing seals for transmission fluid leakage (motor shares housing with single-speed transmission containing Dexron VI ATF). Inspect breather vents for blockage. Use inspection mirror and light to examine all surfaces, including top and rear areas.
10. 10

    Inspect motor bearings
    With motor supported, manually rotate the motor rotor by turning the motor shaft or output shaft. Feel for smooth rotation without binding, roughness, or excessive play. Use dial indicator to measure axial end play (should be minimal, typically less than 0.5mm). Listen for grinding or clicking sounds indicating bearing wear.
    ℹ️Some magnetic cogging or resistance is normal in permanent magnet motors. Focus on irregularities or roughness.
11. 11

    Inspect cooling system connections
    Inspect motor and inverter cooling system connections, hoses, and fittings. Check for coolant leakage, corrosion on fittings, or deteriorated hoses. Verify coolant level in expansion tank is correct (system uses Dex-Cool orange coolant). Look for signs of coolant contamination or discoloration.
12. 12

    Inspect rotor position sensor
    Visually inspect the resolver or encoder (rotor position sensor) mounted to the motor housing. Check for physical damage, secure mounting, proper connector engagement, and clean sensor face. Verify air gap between sensor and rotor target if accessible using feeler gauge (typically 0.5-1.0mm).
13. 13

    Inspect motor windings (if accessible)
    If motor design allows visual access to stator windings through inspection ports, examine for signs of overheating (discolored insulation), physical damage, or contamination. Look for burned or melted insulation. If thermal imaging camera is available, compare winding temperatures if motor has recently operated (should be relatively uniform).
14. 14

    Perform electrical resistance checks
    Using a digital multimeter, measure and record resistance between motor phase terminals (typically U, V, W phases). Resistances should be low (typically 0.01-0.1 ohms) and balanced within 5% between phases. Measure insulation resistance from each phase to motor housing ground (should be greater than 1 megohm). Record all values for comparison to specifications.
    ℹ️Resistance values are for reference only. Consult factory service data for exact specifications for this motor.
15. 15

    Inspect inverter and power electronics
    Visually inspect the inverter assembly attached to motor housing. Check for coolant leaks, damaged cooling fins, loose connections, or signs of overheating. Verify all inverter mounting fasteners are secure. Check for any fault codes stored in the drive unit control module using appropriate scan tool.

Reassembly

1. Raise motor assembly back into position using support jack, aligning mounting points carefully
2. Install Motor Mount Bolts and Mounting Bolts, torquing to specification in a cross-pattern sequence
3. Apply thread locking compound to bolts as specified in service information
4. Install support brackets and torque Bracket Bolts to specification
5. Install new motor cover gasket if original was damaged, then reinstall protective covers with Cover Screws torqued to specification
6. Reconnect all low-voltage connectors, sensors, and control module connections, ensuring positive engagement
7. Reinstall Sensor Bolts and Connector Bolts to specification
8. Clean high-voltage connector faces with appropriate electrical contact cleaner if any contamination was found
9. Reinstall high-voltage cables, using new seals if originals show any damage, and torque High-Voltage Connector Bolts to specification
10. Remove all insulating caps and verify no tools or materials are left in motor compartment
11. Reinstall front underbody shields and splash guards
12. Reinstall front wheels and torque lug nuts to specification
13. Lower vehicle to ground
14. Reconnect 12V auxiliary battery negative terminal
15. Reinstall high-voltage service disconnect plug and secure cover
16. Remove high-voltage warning tags

Verification

• Perform high-voltage system integrity check using scan tool to verify no isolation faults are present
• Clear any diagnostic trouble codes that may have been set during service
• With vehicle in Park and brake applied, power on vehicle and verify Ready indicator illuminates normally
• Listen for any unusual sounds from motor area during initial power-up
• Perform a brief test drive, monitoring for proper motor operation, smooth acceleration, regenerative braking function, and absence of unusual noises or vibrations
• Recheck all high-voltage and low-voltage connections are secure and show no signs of arcing or heating
• Verify no coolant or transmission fluid leaks are present after test drive
• Document all inspection findings, measurements, and any anomalies in service records

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