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Home >> Chevrolet >> 2012 >> Volt L4-1.4L Elect >> Repair and Diagnosis >> Hybrid Drive Systems >> Service Precautions >> High Voltage Disabling >> Part 1

Part 1




High Voltage Disabling

Special Tools
* EL-50774 - Low/High Resistance Meter
* EL-48900 - HEV Safety Kit
* EL-50554-1 - 14 V Power Inverter Assurance Harness
* EL-50554-2 - Charger Assurance Harness

For equivalent regional tools, refer to Special Tools Tools and Equipment.

Danger: Ensure all High Voltage safety procedures are followed. Failure to follow the procedure exactly as written may result in serious injury or death.


Danger: Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:


* Safety glasses with appropriate side shields when within 50 feet of the vehicle, either indoors or outdoors

* Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors


- Visually and functionally inspect the gloves before use.

- Wear the Insulation gloves at all times when working with the high voltage battery assembly, whether the system is energized or not.


Failure to follow the procedure exactly as written may result in serious injury or death.


The High Voltage Disabling procedure will perform the following tasks:

* Identify how to disable high voltage.
* Identify how to test for the presence of high voltage.
* Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.

Danger: The Volt Battery Pack will utilize an exchange program. Please consult the most recent revision of bulletin/PI #PIP4841, available in Service Information (SI), for a list of approved Volt Battery Pack service procedures. Components that may be removed and serviced without exchanging the complete battery pack are identified in the bulletin/PI. Please contact the GM Technical Assistance Center (1-877-446-8227) if you have any questions.


Servicing the A4 Hybrid/EV Battery Pack, 360 V DC Cables and General Vehicle Servicing
1. Review the high voltage safety information. Refer to High Voltage Safety High Voltage Safety
2. Disconnect and remove all 12 V battery chargers and the AC Charge Cable from the X98 Hybrid Battery Charger Receptacle.
3. Remove all keyless entry transmitters from the vehicle and secure in a place outside the vehicle.
4. Attempt to start the vehicle with the Ignition Mode Switch.

• If the vehicle enters Propulsion System Active mode or the engine starts, locate and remove all keyless entry transmitters from within the vehicle and return to step 3.

Note: The 12 V battery must be disconnected to ensure proper test results.

5. Disconnect the 12 V battery. Refer to Battery Negative Cable Disconnection and Connection Battery Negative Cable Disconnection and Connection




6. Remove the S15 manual service disconnect (1). Place the manual service disconnect in a secure place outside the vehicle.
7. Cover the exposed high voltage opening with UL(R) listed, or equivalent, insulation tape rated at a minimum of 600 V.
8. Wait 5 minutes before continuing, to allow the high voltage capacitors to discharge.
9. Verify the EL-50554 - voltage disable assurance test harness Using the DMM, verify the EL-50554-1 and EL-50554-2 cables measure less than 1 ohm at the following points:

* High voltage DC (-360 V) negative terminal B to the High voltage DC (-360 V) negative terminal.
* High voltage DC (+360 V) positive terminal A to the High voltage DC (+360 V) positive terminal.

• If the test result was greater than the specified range, repair or replace the EL-50554-1 or EL-50554-2 and repeat all measurements.

10. Using the DMM, verify the EL-50554-1 and EL-50554-2 have infinite resistance between the High voltage DC (+360 V) positive terminal A to High voltage DC (-360 V) negative terminal B.

• If the test result was less than the specified range, repair or replace the EL-50554-1 or EL-50554-2 and repeat all measurements.

11. Verify the EL-50554-1 and EL-50554-2 High voltage DC (-360 V) negative terminal B and the High voltage DC (+360 V) positive terminal A have the proper terminal tension. Refer to Testing for Proper Terminal Contact. Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

• If a poor connection is found, repair or replace the EL-50554-1 or EL-50554-2 and repeat all measurements.

12. Remove the T6 power inverter module cover. Refer to Drive Motor Generator Power Inverter Module Cover Replacement Drive Motor Generator Power Inverter Module Cover Replacement.

Note: Wear your High Voltage Insulation gloves until you have determined that a high voltage exposure risk is no longer present.

13. Disconnect the X3 harness connector at the T6 power inverter module.

Note: A 9 V DC battery can be used to test the DMM.

14. Test the DMM by measuring a 12 V battery.

• If the DMM does not properly measure a 12 V battery, repair or replace the DMM and repeat all voltage measurements.

Note: 5 minutes must have elapsed since removing the manual service disconnect before continuing to allow the high voltage capacitors to discharge and ensure proper test results.

15. Verify that the voltage has been disabled at the T6 power inverter module. Using the DMM, verify the voltage measures less than 3 V at the following points:

* High voltage DC (-360 V) negative terminal B to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A and high voltage DC (-360 V) negative terminal B.

• If the test result was greater than 3 V, leave the DMM connected to the terminals until the voltage drops below 3 V to allow the high voltage capacitors to discharge. Continue to the next step once the voltage is below 3 V.

16. Verify that the voltage has been disabled at the X3 harness connector at the T6 power inverter module. Using the DMM, verify the voltage measures less than 3 V at the following points:

* High voltage DC (-360 V) negative terminal B to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A and high voltage DC (-360 V) negative terminal B.

• If the test result was greater than 3 V, there is a stuck closed contactor and a loss of isolation within the A4 battery pack assembly. Refer to Hybrid\EV Battery Voltage Present Hybrid/EV Battery Voltage Present.

17. Remove the 3 catalytic converter nuts. Disconnect catalytic converter from the exhaust manifold. Move and secure the exhaust to one side. Refer to Catalytic Converter Replacement Service and Repair.
18. Remove the front exhaust pipe heat shield. Refer to Exhaust Pipe Heat Shield Replacement (Front) Exhaust Pipe Heat Shield Replacement (Front)Exhaust Pipe Heat Shield Replacement (Center) Exhaust Pipe Heat Shield Replacement (Center)Exhaust Pipe Heat Shield Replacement (Rear) Exhaust Pipe Heat Shield Replacement (Rear).




19. Disconnect the X1 (1) and X2 (2) harness connectors at the A28 hybrid battery contactor assembly.
20. Disconnect the high voltage interlock harness connector listed below at the A28 hybrid battery contactor assembly.

* F118 (6) hybrid battery pack connector jumper connector.
* X6 (7) 14 V power module jumper connector.
* X7 (8) battery charger jumper connector.

21. Disconnect the X4 (4) harness connector at the A28 hybrid battery contactor assembly.
22. Connect the EL-50554-1 to the A28 hybrid battery contactor assembly. Using the DMM, verify the voltage measures less than 3 V at the following points:

* High voltage DC (-360 V) negative terminal B to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A and high voltage DC (-360 V) negative terminal B.

• If the test result was greater than 3 V, there is a stuck closed contactor and a loss of isolation within the A4 battery pack assembly. Refer to Hybrid\EV Battery Voltage Present Hybrid/EV Battery Voltage Present.

23. Verify that the voltage has been disabled at the X4 (4) harness connector at the A28 hybrid battery contactor assembly. Using the DMM, verify the voltage measures less than 3 V at the following points:

* High voltage DC (-360 V) negative terminal B to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A and high voltage DC (-360 V) negative terminal B.

• If the test result was greater than 3 V, leave the DMM connected to the terminals until the voltage drops below 3 V to allow the high voltage capacitors to discharge. Continue to the next step once the voltage is below 3 V.

24. Disconnect the X5 (5) harness connector at the A28 hybrid battery contactor assembly.
25. Connect the EL-50554-2 to the A28 hybrid battery contactor assembly. Using the DMM, verify the voltage measures less than 3 V at the following points:

* High voltage DC (-360 V) negative terminal B to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A and high voltage DC (-360 V) negative terminal B.

• If the test result was greater than 3 V, there is a stuck closed contactor and a loss of isolation within the A4 battery pack assembly. Refer to Hybrid\EV Battery Voltage Present Hybrid/EV Battery Voltage Present.

26. Verify that the voltage has been disabled at the X5 (5) harness connector at the A28 hybrid battery contactor assembly harness. Using the DMM, verify the voltage measures less than 3 V at the following points:

* High voltage DC (-360 V) negative terminal B to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A and high voltage DC (-360 V) negative terminal B.

• If the test result was greater than 3 V, leave the DMM connected to the terminals until the voltage drops below 3 V to allow the high voltage capacitors to discharge. Continue to the next step once the voltage is below 3 V.

27. Disconnect the X3 (3) harness connector at the A28 hybrid battery contactor assembly.
28. Verify that the voltage has been disabled at the A28 hybrid battery contactor assembly. Using the DMM, verify the voltage measures less than 3 V at the following points:

* High voltage DC (-360 V) negative terminal B to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A and high voltage DC (-360 V) negative terminal B.

• If the test result was greater than 3 V, there is a stuck closed contactor and a loss of isolation within the A4 battery pack assembly. Refer to Hybrid\EV Battery Voltage Present Hybrid/EV Battery Voltage Present.

Note: A 9 V DC battery can be used to test the DMM.

29. Test the DMM by measuring a 12 V battery.

• If the DMM does not properly measure a 12 V battery, repair or replace the DMM and repeat all voltage measurements.

30. If all the test results were less than 3 V, the A4 battery pack assembly, 360 V DC power inverter cables or general vehicle can now be serviced.

Servicing the T6 Power Inverter Module Assembly or T12 Transmission
1. Review the high voltage safety information. Refer to High Voltage Safety High Voltage Safety
2. Disconnect and remove all 12 V battery chargers and the AC Charge Cable from the X98 Hybrid Battery Charger Receptacle.
3. Remove all keyless entry transmitters from the vehicle and secure in a place outside the vehicle.
4. Attempt to start the vehicle with the Ignition Mode Switch.

• If the vehicle enters Propulsion System Active mode or the engine starts, locate and remove all keyless entry transmitters from within the vehicle and return to step 3.

Note: The 12 V battery must be disconnected to ensure proper test results.

5. Disconnect the 12 V battery. Refer to Battery Negative Cable Disconnection and Connection Battery Negative Cable Disconnection and Connection




6. Remove the S15 manual service disconnect (1). Place the manual service disconnect in a secure place outside the vehicle.
7. Cover the exposed high voltage opening with UL(R) listed, or equivalent, insulation tape rated at a minimum of 600 V.
8. Wait 5 minutes before continuing, to allow the high voltage capacitors to discharge.
9. Remove the T6 power inverter module cover. Refer to Drive Motor Generator Power Inverter Module Cover Replacement Drive Motor Generator Power Inverter Module Cover Replacement.

Note: Wear your High Voltage Insulation gloves until you have determined that a high voltage exposure risk is no longer present.

10. Disconnect the X3 harness connector at the T6 power inverter module.

Note: A 9 V battery can be used to test the DMM.

11. Test the DMM by measuring a 12 V battery.

• If the DMM does not properly measure a 12 V battery, repair or replace the DMM and repeat all voltage measurements.

Note: 5 minutes must have elapsed since removing the manual service disconnect before continuing to allow the high voltage capacitors to discharge and ensure proper test results.

12. Verify that the voltage has been disabled at the T6 power inverter module. Using the DMM, verify the voltage measures less than 3 V at the following points:

* High voltage DC (-360 V) negative terminal B to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A and high voltage DC (-360 V) negative terminal B.

• If the test result was greater than 3 V, leave the DMM connected to the terminals until the voltage drops below 3 V to allow the high voltage capacitors to discharge. Continue to the next step once the voltage is below 3 V.

13. Verify that the voltage has been disabled at the X3 harness connector at the T6 power inverter module. Using the DMM, verify the voltage measures less than 3 V at the following points:

* High voltage DC (-360 V) negative terminal B to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A and high voltage DC (-360 V) negative terminal B.

• If the test result was greater than 3 V, there is a stuck closed contactor and a loss of isolation within the A4 battery pack assembly. Refer to Hybrid\EV Battery Voltage Present Hybrid/EV Battery Voltage Present.

14. Disconnect the X4 harness connector at the T6 power inverter module.
15. Verify that the voltage has been disabled at the T6 power inverter module. Using the DMM, verify the voltage measures less than 3 V at the following points:

* High voltage DC (-360 V) negative terminal B to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A and high voltage DC (-360 V) negative terminal B.

• If the test result was greater than 3 V, leave the DMM connected to the terminals until the voltage drops below 3 V to allow the high voltage capacitors to discharge. Continue to the next step once the voltage is below 3 V.

16. Verify that the voltage has been disabled at the X4 harness connector at the T6 power inverter module. Using the DMM, verify the voltage measures less than 3 V at the following points:

* High voltage DC (-360 V) negative terminal B to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A to vehicle chassis ground.
* High voltage DC (+360 V) positive terminal A and high voltage DC (-360 V) negative terminal B.

• If the test result was greater than 3 V, leave the DMM connected to the terminals until the voltage drops below 3 V to allow the high voltage capacitors to discharge. Continue to the next step once the voltage is below 3 V.

Note: A 9 V battery can be used to test the DMM.

17. Test the DMM by measuring a 12 V battery.

• If the DMM does not properly measure a 12 V battery, repair or replace the DMM and repeat all voltage measurements.

18. If all the test results were less than 3 V, the T6 power inverter module assembly or T12 transmission can now be serviced.

Servicing the K1 14 V Accessory Power Module
1. Review the high voltage safety information. Refer to High Voltage Safety High Voltage Safety
2. Disconnect and remove all 12 V battery chargers and the AC Charge Cable from the X98 Hybrid Battery Charger Receptacle.
3. Remove all keyless entry transmitters from the vehicle and secure in a place outside the vehicle.
4. Attempt to start the vehicle with the Ignition Mode Switch.

• If the vehicle enters Propulsion System Active mode or the engine starts, locate and remove all keyless entry transmitters from within the vehicle and return to step 3.

Note: The 12 V battery must be disconnected to ensure proper test results.

5. Disconnect the 12 V battery. Refer to Battery Negative Cable Disconnection and Connection Battery Negative Cable Disconnection and Connection




6. Remove the S15 manual service disconnect (1). Place the manual service disconnect in a secure place outside the vehicle.
7. Cover the exposed high voltage opening with UL(R) listed, or equivalent, insulation tape rated at a minimum of 600 V.
8. Wait 5 minutes before continuing, to allow the high voltage capacitors to discharge.
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