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Home >> GMC >> 2021 >> Acadia AT4 >> Repair and Diagnosis >> External Pages >> Different car >> Section 413 (Automatic Transmission - 9T60 (M3G) Or 9T65 (M3W) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P27EF, P27F1, or P27F2 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2023 GMC Acadia. However, it is still accessible from the selected car via links, so may be relevant.
  1. Connect the electrical connector: X1@T12 Automatic Transmission Assembly
  2. Ignition/Vehicle - Off
  3. Disconnect the electrical connector: X1@T12 Automatic Transmission Assembly
  4. Ignition - On/Vehicle - In Service Mode
  5. Test for 8.8 to 9.2 V between the test points: 9 V Reference circuit terminal 7 & Ground
    • If less than 8.8 V 
    1. Connect the electrical connector: X1@T12 Automatic Transmission Assembly
    2. Ignition/Vehicle - Off
    3. Disconnect the electrical connector: X1@T12 Automatic Transmission Assembly
    4. Disconnect the electrical connector: K71 Transmission Control Module
    5. Test for infinite resistance between the test points: 9 V Reference circuit terminal 7@Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    6. Test for less than 2 ohms between the test points: 9 V Reference circuit terminal 7@Component harness & Terminal 8@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 greater than 9.2 V 
    1. Connect the electrical connector: X1@T12 Automatic Transmission Assembly
    2. Ignition/Vehicle - Off
    3. Disconnect the electrical connector: X1@T12 Automatic Transmission Assembly
    4. Disconnect the electrical connector: K71 Transmission Control Module
    5. Ignition - On/Vehicle - In Service Mode
    6. Test for less than 1 V between the test points: 9 V Reference circuit terminal 7@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 between 8.8 and 9.2 V 
  6. Install & Setup - EL-38522 Variable Signal Generator
    • Voltage - 5 V
    • Frequency - 10 kHz
    • Duty Cycle - 40%
    • Red lead@Signal circuit terminal 20 X1@T12 Automatic Transmission Assembly
    • Black lead@Ground
  7. Verify the scan tool parameter: Transmission Range Control Valve 2 Position Switch = 2.0 to 2.3 V
    • If less than 2.0 V 
    1. Remove - Jumper Wire(s)
    2. Connect the electrical connector: X1@T12 Automatic Transmission Assembly
    3. Ignition/Vehicle - Off
    4. Disconnect the electrical connector: X1@T12 Automatic Transmission Assembly
    5. Disconnect the electrical connector: K71 Transmission Control Module
    6. Test for infinite resistance between the test points: Signal circuit terminal 60@Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    7. Test for less than 2 ohms between the test points: Signal circuit terminal 20 X1@Component harness & Terminal 60@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 greater than 2.3 V 
    1. Connect the electrical connector: X1@T12 Automatic Transmission Assembly
    2. Ignition/Vehicle - Off
    3. Disconnect the electrical connector: X1@T12 Automatic Transmission Assembly
    4. Disconnect the electrical connector: K71 Transmission Control Module
    5. Ignition - On/Vehicle - In Service Mode
    6. Test for less than 1 V between the test points: Signal circuit terminal 20 X1@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 between 2.0 and 2.3 V 
  8. Remove the transmission cover.
  9. Connect the electrical connector: X1@T12 Automatic Transmission AssemblyX1
  10. Disconnect the component: B315B Transmission Range Control Valve 2 Position Switch
  11. Test for 8.8 to 9.2 V between the test points: 9 V Reference circuit terminal 2 & Ground
    • If less than 8.8 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: X1@T12 Automatic Transmission Assembly
    3. Test for infinite resistance between the test points: 9 V Reference 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
    4. Test for less than 2 ohms between the test points: 9 V Reference circuit terminal 2@Component harness & Terminal 1 X2@Component harness
      • If greater than 2 ohms - Replace the component: Automatic Transmission Wiring Harness
      • If less than 2 ohms - Replace the component: B315B Transmission Range Control Valve 2 Position Switch
    • If greater than 9.2 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: X1@T12 Automatic Transmission Assembly
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: 9 V Reference circuit terminal 2@Component harness & Ground
      • If greater than 1 V - Replace the component: Automatic Transmission Wiring Harness
      • If less than 1 V - Replace the component: K71 Transmission Control Module
    • Go to next step: If between 8.8 and 9.2 V 
  12. Install & Setup - EL-38522 Variable Signal Generator
    • Voltage - 5 V
    • Frequency - 10 kHz
    • Duty Cycle - 40%
    • Red lead@Signal circuit terminal 1@Component harness
    • Black lead@Ground
  13. Verify the scan tool parameter: Transmission Range Control Valve 2 Position Switch = 2.0 to 2.3 V
    • If less than 2.0 V 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the electrical connector: K71 Transmission Control Module
    3. Test for infinite resistance between the test points: Signal circuit terminal 1@Component harness & Ground
      • If less than infinite resistance - Replace the component: Automatic Transmission Wiring Harness
      • Go to next step: If infinite resistance
    4. Test for less than 2 ohms between the test points: Signal circuit terminal 1@Component harness & Terminal 9 X2@Component harness
      • If greater than 2 ohms - Replace the component: Automatic Transmission Wiring Harness
      • If less than 2 ohms - Replace the component: B315B Transmission Range Control Valve 2 Position Switch
    • If greater than 2.3 V 
    1. Connect the electrical connector: X1@T12 Automatic Transmission Assembly
    2. Ignition/Vehicle - Off
    3. Disconnect the electrical connector: X1@T12 Automatic Transmission Assembly
    4. Disconnect the electrical connector: K71 Transmission Control Module
    5. Ignition - On/Vehicle - In Service Mode
    6. Test for less than 1 V between the test points: Signal circuit terminal 1@Component harness & Ground
      • If greater than 1 V - Replace the component: Automatic Transmission Wiring Harness
      • If less than 1 V - Replace the component: B315B Transmission Range Control Valve 2 Position Switch
    • Go to next step: If between 2.0 and 2.3 V 
  14. Test or replace the component: B315B Transmission Range Control Valve 2 Position Switch
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