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Home >> GMC >> 2021 >> Acadia AT4 >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transmission - 9T50 (M3H), 9T60 (M3G) Or 9T65 (M3W) - Diagnostic Information And Procedures >> Diagnostic Information and Procedures >> DTC P27EB, P27ED, or P27EE >> Circuit/System Testing

Circuit/System Testing

  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector: X1 @ T12 Automatic Transmission Assembly
  3. Ignition - On / Vehicle - In Service Mode
  4. 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 
  5. Install the special tool:<special tool><special tool-no>EL-38522</special tool-no><special tool-desc>Variable Signal Generator</special tool-desc></special tool>
    • Set the voltage to 5 V
    • Set the frequency to 10k Hz
    • Set the duty cycle to 40%%
    • Red lead @ Signal circuit terminal 21 X1 @ T12 Automatic Transmission Assembly
    • Black lead @ Ground
  6. Verify the scan tool parameter: Transmission Range Control Valve 1 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 62 @ 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 21 X1 @ Component harness & Terminal 62 @ 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 21 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 
  7. Remove the transmission cover.
  8. Connect the electrical connector: X1 @ T12 Automatic Transmission Assembly
  9. Disconnect the component: B315A Transmission Range Control Valve 1 Position Switch
  10. 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: B315A Transmission Range Control Valve 1 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 
  11. Install the special tool:<special tool><special tool-no>EL-38522</special tool-no><special tool-desc>Variable Signal Generator</special tool-desc></special tool>
    • Set the voltage to 5 V
    • Set the frequency to 10k Hz
    • Set the duty cycle to 40%%
    • Red lead @ Signal circuit terminal 1 @ Component harness
    • Black lead @ Ground
  12. Verify the scan tool parameter: Transmission Range Control Valve 1 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 1 @ Component harness & Ground
      • If less than infinite resistance - Replace the component: Automatic Transmission Wiring Harness
      • Go to next step: If infinite resistance
    7. Test for less than 2 ohms between the test points: Signal circuit terminal 1 @ Component harness & Terminal 8 X2 @ Component harness
      • If greater than 2 ohms - Replace the component: Automatic Transmission Wiring Harness
      • If less than 2 ohms - Replace the component: B315A Transmission Range Control Valve 1 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: B315A Transmission Range Control Valve 1 Position Switch
    • Go to next step: If between 2.0 and 2.3 V 
  13. Test or replace the component: B315A Transmission Range Control Valve 1 Position Switch
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