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Home >> Chevrolet >> 2021 >> Trailblazer RS, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 11 (Automatic Transmission - VT40 (MRG) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P0964-P0968, P0970, P0971, P2670, P2671, P2727, P2729, or P2730 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Ignition/Vehicle - Off
    2. NOTE:

    To turn the ignition off on vehicles equipped with a push button ignition switch, the wiring harness connector must be connected to the component T12. A valid park input signal to the control module K71 is required to turn the ignition off.

  2. Disconnect the electrical connector: X1 @ T12 Automatic Transmission Assembly
  3. Connect a test lamp between the test points: Control circuit terminal 28 & Ground
  4. Ignition - On / Vehicle - In Service Mode
  5. Perform the scan tool control function: High Side Driver 2 - On and Off

    Verify the test lamp turns On and Off.

    • If the test lamp is always Off 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector:
      • K71 Transmission Control Module
      • X1 @ T12 Automatic Transmission Assembly
    3. Test for infinite resistance between the test points: Control circuit terminal 28 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    4. Test for less than 2 ohms between the test points: Control circuit terminal 28 @ Component harness & The other end of the circuit @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K71 Transmission Control Module
    • If the test lamp is always On 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector:
      • K71 Transmission Control Module
      • X1 @ T12 Automatic Transmission Assembly
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Control circuit terminal 28 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component: K71 Transmission Control Module
    • Go to next step: If the test lamp turns On and Off 
  6. Verify DTC P2670, P2671 is not set.
    • If the DTC is set 

      Refer to step 14

    • Go to next step: If the DTC is not set 
  7. Ignition/Vehicle - Off
  8. Disconnect the electrical connector:
    • K71 Transmission Control Module
    • X1 @ T12 Automatic Transmission Assembly
  9. Test for less than 2 ohms between the test points:
    • {P0964 - P0967} Control circuit terminal 26 @ Component harness & The other end of the circuit @ Control module harness
    • {P0968, P0970, P0971} Control circuit terminal 24 @ Component harness & The other end of the circuit @ Control module harness
    • {P2727, P2729, P2730} Control circuit terminal 14 @ Component harness & The other end of the circuit @ Control module harness
    • If 2 ohms or greater 

      Repair the open/high resistance in the circuit.

    • Go to next step: If less than 2 ohms 
  10. Test for infinite resistance between the test points:
    • {P0960 - P0963} Control circuit terminal 26 @ Component harness & Ground
    • {P0968, P0970, P0971} Control circuit terminal 24 @ Component harness & Ground
    • {P2736 - P2739} Control circuit terminal 14 @ Component harness & Ground
    • If less than infinite resistance 

      Repair the short to ground on the circuit.

    • Go to next step: If infinite resistance 
  11. Ignition - On / Vehicle - In Service Mode
  12. Test for less than 1 V between the test points:
    • {P0960 - P0963} Control circuit terminal 26 @ Component harness & Ground
    • {P0968, P0970, P0971} Control circuit terminal 24 @ Component harness & Ground
    • {P2736 - P2739} Control circuit terminal 14 @ Component harness & Ground
    • If 1 V or greater 

      Repair the short to voltage on the circuit.

    • Go to next step: If less than 1 V 
  13. Ignition/Vehicle - Off
  14. Remove the component: Transmission Cover
  15. Connect the electrical connector: X1 @ T12 Automatic Transmission Assembly
  16. Disconnect the appropriate electrical connector: Q77 Transmission Control Solenoid Valve
  17. Connect a test lamp between the test points: Control circuit terminal 1 & Ground
  18. Ignition - On / Vehicle - In Service Mode
  19. Perform the scan tool control function: High Side Driver 2 - On and Off

    Verify the test lamp turns On and Off.

    • If the test lamp does not turn On and Off 

      Replace the component: Automatic Transmission Wiring Harness

    • Go to next step: If the test lamp turns On and Off 
  20. Test for less than 2 ohms between the test points: Control circuit terminal 2 @ Component harness & The other end of the circuit @ Control module harness
    • If 2 ohms or greater 

      Replace the component: Automatic Transmission Wiring Harness

    • Go to next step: If less than 2 ohms 
  21. Test for infinite resistance between the test points: Control circuit terminal 2 @ Component harness & Ground
    • If less than infinite resistance 

      Replace the component: Automatic Transmission Wiring Harness

    • Go to next step: If infinite resistance 
  22. Test or replace the component: Q77 Transmission Control Solenoid Valve
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