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Home >> Buick >> 2015 >> Regal GS, AWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 7 (Hybrid/EV Energy Storage System) >> Diagnostic Information and Procedures >> DTC P0C77 or P0C78: Hybrid/EV Battery System Precharge Time >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
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.

WARNING:

The eAssist battery pack assembly will utilize an exchange program. Please consult the most recent revision of bulletin/PI# PIC5520, available in Service Information (SI), for a list of approved eAssist battery pack assembly service procedures. Components that may be removed and serviced without exchanging the complete battery pack assembly are identified in the bulletin/PI. Please contact the GM Technical Assistance Center (1-877-446-8227) if you have any questions.

    NOTE:

    In High Voltage Disabling  , perform the disabling procedure for servicing components within the A4 Hybrid/EV Battery Pack. The C4A Hybrid/EV Battery Section 1 and C4B Hybrid/EV Battery Section 2 will be disconnected as part of the disabling procedure.

  1. Ignition OFF, disable high voltage at the A4 Hybrid/EV Battery Pack. Refer to High Voltage Disabling .
  2. Connect the X1, X2, and X3 harness connectors at the K59 Starter/Generator Control Module.
  3. Disconnect the X1 and X2 harness connectors at the KR134 Pre-Charge Contactor.
  4. Connect the 12 V battery, ignition ON.
  5. Verify a test lamp illuminates between the B+ circuit terminal A X1 and ground.
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the harness connector at the K59 Starter/Generator Control Module.
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K59 Starter/Generator Control Module.
    • If the test lamp illuminates 
  6. Test for less than 1 V between the control circuit terminal A X2 and ground.
    • If 1 V or greater 
    1. Ignition OFF, disconnect the X4 harness connector at the K59 Starter/Generator Control Module.
    2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K59 Starter/Generator Control Module.
    • If less than 1 V 
  7. Install a 10 A fused jumper wire between the B+ terminal A X1 and 12 V. Install a jumper wire between the control terminal A X2 and ground.
    8. NOTE:

    This step checks the resistance of the closed contactor. Excessive resistance in the closed contacts may cause a slow pre-charge. To verify the resistance, the contactor must be closed. To close the contactor, all terminals at the contactor must be removed and the contactor B+ and control circuits jumpered to B+ and ground. This will close the contacts and allow the resistance of the contacts to be measured.

  8. Test for less than 2 Ω between the high voltage terminals of the closed KR134 Pre-Charge Contactor.
    • If 2 Ω or greater 

      Replace the KR134 Pre-Charge Contactor.

    • If less than 2 Ω 
  9. Ignition OFF, connect the X1 and X2 harness connectors at the KR134 Pre-Charge Contactor. Disconnect the X4 harness connector at the K59 Starter/Generator Control Module.
  10. Test for infinite resistance between the control circuit terminal 6 and ground.
    • If less than infinite resistance 
    1. Ignition OFF, disconnect the X2 harness connector at the KR134 Pre-Charge Contactor
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, test or replace the KR134 Pre-Charge Contactor.
    • If infinite resistance 
  11. Test for 90-115 Ω between the B+ circuit terminal 4 and the control circuit terminal 6.
    • If not between 90-115 Ω 
    1. Ignition OFF, disconnect the X2 harness connector at the KR134 Pre-Charge Contactor.
    2. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the KR134 Pre-Charge Contactor.
    • If between 90-115 Ω 
  12. Test for infinite resistance between the control circuit terminal 5 and ground.
    • If less than infinite resistance 
    1. Ignition OFF, disconnect the X1 harness connector at the KR38 Main Contactor.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, test or replace the KR38 Main Contactor.
    • If infinite resistance 
  13. Test for infinite resistance between the high voltage terminals of the open KR38 Main Contactor.
    • If not infinite resistance 

      Replace the KR38 Main Contactor.

    • If infinite resistance 
  14. Test for 5-10 Ω between the R25 Hybrid/EV Battery Pre-Charge Resistor terminals.
    • If not between 5-10 Ω 

      Replace the R25 Hybrid/EV Battery Pre-Charge Resistor.

    • If between 5-10 Ω 
  15. Test each of the high voltage circuits and terminals supplying the R25 Hybrid/EV Battery Pre-Charge Resistor and KR134 Pre-Charge Contactor for less than 2 Ω end to end.
    • If 2 Ω or greater 

      Replace the appropriate harness.

    • If less than 2 Ω 
  16. Replace the K59 Starter/Generator Control Module.
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