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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 515 (Hybrid/EV Cooling System) >> Diagnostic Information and Procedures >> DTC P0A81 or P0BC1 >> Circuit/System Testing

Circuit/System Testing

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WARNING:

Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.

The High Voltage Disabling procedure includes the following steps:

  • 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.

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

  • Safety glasses with appropriate side shields when within 15 meters (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 with leather protectors at all times when working with the high voltage battery assembly, whether the system is energized or not.

Failure to follow the procedures may result in serious injury or death.

NOTE:

Perform the Generator Battery Vent Fan test first

Generator Battery Vent Fan Test

  1. Ignition OFF, disable the high voltage at the drive motor generator battery. Refer to High Voltage Disabling .
  2. Ignition OFF, disconnect the generator battery vent fan.
  3. Connect the 12 V battery.
  4. Test for less than 5 Ω between the generator battery vent fan ground circuit terminal 3 and ground
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  5. Connect a test lamp between the control circuit terminal 2 and the ground circuit terminal 3.
  6. Command the battery pack vent fan speed between 0 and 60 percent with a scan tool. The test lamp should turn ON and OFF after a 10 second delay.
    • If the test lamp does not turn ON and OFF, refer to Generator Battery Vent Fan Relay test.
  7. Connect a DMM between the control circuit terminal 4 and ground.
  8. Command the battery vent fan to 60 percent with a scan tool. Test for less than 1 V after a 10 second delay.
    • If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the drive motor generator battery control module.
  9. Command the battery vent fan to 0 percent with a scan tool. Switch the DMM to the diode test. The DMM reading should display O.L.
    • If less than the specified value, test the control circuit for a short to ground. If the circuits test normal, replace the drive motor generator battery control module.
  10. Command the battery vent fan to 60 percent with a scan tool. The reading should be less than 3 V.
    • If less than the specified range or displaying O.L., test the control circuit for an open/high resistance. If the circuits test normal, replace the drive motor generator battery control module.

Generator Battery Vent Fan Relay Test

  1. Disconnect the harness connector at the battery vent fan relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 4 and ground.
    • If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the B+ circuit terminal 3 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 4 for a short to ground. If the circuit tests normal, replace the battery vent fan relay.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 2 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  5. Connect a 15 A fused jumper wire between the B+ circuit terminal 3 and the control circuit terminal 4. Verify the generator battery vent fan is activated.
    • If the cooling fan does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the generator battery vent fan.
  6. Connect a test lamp between the B+ circuit terminal 2 and the control circuit terminal 1.
  7. Command the battery pack vent fan speed between 0 and 60 percent with a scan tool. The test lamp should turn ON and OFF after a 10 second delay.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the drive motor generator battery control module.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the drive motor generator battery control module.
  8. If all circuits test normal, test or replace the generator battery vent fan relay.
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