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Home >> Cadillac >> 2018 >> Escalade Base, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 21 (Automatic Transmission - 8L90 (M5U) - Diagnostic Information And Procedures) >> Diagnostic Information And Procedures >> DTC P0722, P0723, P077C, Or P077D: Output Speed Sensor Circuit >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2018 Chevrolet Suburban 3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: X175 @ T12 Automatic Transmission Assembly
  3. Ignition - On/Vehicle - In Service Mode
  4. Test for 8.5 to 9.5 V between the test points: 9 V Reference circuit 1 Terminal 25 @ Component harness & Ground
    • If less than 8.5 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: X175 @ K71 Transmission Control Module
    3. Test for infinite resistance between the test points: 9 V Reference circuit 1 Terminal 25 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance
    4. Test for less than 2 ohms between the test points: 9 V Reference circuit 1 Terminal 25 @ Component harness & Terminal 7 @ 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 9.5 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K71 Transmission Control Module
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: 9 V Reference circuit 1 Terminal 25 @ 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 8.5 and 9.5 V 
  5. Ignition/Vehicle - Off
  6. Install the special tool: EL-38522 Variable Signal Generator
    • Red lead @ Signal circuit terminal 24
    • Black lead @ Ground
    • Set the voltage to 5 V
    • Set the frequency to 300 Hz
    • Set the duty cycle to 50%
  7. Ignition - On/Vehicle - In Service Mode
  8. Verify the scan tool parameter: Transmission OSS = 250 to 280 RPM
    • If not between 250 and 280 RPM 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K71 Transmission Control Module
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Signal circuit terminal 24 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for infinite resistance between the test points: Signal circuit terminal 24 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance
    7. Test for less than 2 ohms between the test points: Signal circuit terminal 24 @ Component harness & Terminal 14 @ 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
    • Go to next step: If between 250 and 280 RPM 
  9. Ignition/Vehicle - Off
  10. Connect the electrical connector: X175 @ T12 Automatic Transmission Assembly
  11. Remove the component: Automatic Transmission Fluid Pan
  12. Disconnect the electrical connector: B14A Transmission Output Shaft Speed Sensor
  13. Ignition - On/Vehicle - In Service Mode
  14. Test for 8.5 to 9.5 V between the test points: 9 V Reference circuit 1 Component terminal 2 & Ground
    • If not between 8.5 and 9.5 V 

      Replace the component: Automatic Transmission Wiring Harness

    • Go to next step: If between 8.5 and 9.5 V 
  15. Ignition Off
  16. Install the special tool: EL-38522 Variable Signal Generator
    • Red lead @ Signal circuit terminal 1
    • Black lead @ Ground
    • Set the voltage to 4 V
    • Set the frequency to 300 Hz
    • Set the duty cycle to 50%
  17. Ignition - On/Vehicle - In Service Mode
  18. Verify the scan tool parameter: Transmission OSS = 250 to 280 RPM
    • If not between 250 to 280 RPM 

      Replace the component: Automatic Transmission Wiring Harness

    • Go to next step: If between 250 to 280 RPM 
  19. Remove the component: B14A Transmission Output Shaft Speed Sensor
  20. Inspect the following components: Output Carrier Assembly - Damaged or misaligned reluctor ring.
    • If a condition exists 

      Replace the component: Output Carrier Assembly

    • Go to next step: If no condition exists 
  21. Replace the component: B14A Transmission Output Shaft Speed Sensor
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