LEMON Manuals: Even more car manuals for everyone
Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 62 (Automatic Transmission - 8L45 (M5N) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P0721-P0723, P077C, P077D, P172A, or P172B >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT4. 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. NOTE:

    Testing for steps 4 to 20 is performed on the control module K71 side of the harness connector.

  5. Test for 8.4 to 9.6 V between the test points: 9 V Reference circuit terminal 25 @ Component harness & Ground
    • If less than 8.4 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K71 Transmission Control Module
    3. Test for infinite resistance between the test points: 9 V Reference circuit terminal 25 @ 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: 9 V Reference circuit terminal 25 @ 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 greater than 9.6 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 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 8.4 and 9.6 V 
  6. Ignition/Vehicle - Off
  7. Install - EL-38522  Variable Signal Generator
    • Voltage - 5 V
    • Frequency - 300 Hz
    • Duty Cycle - 50%
    • Black lead @ Ground
    • Red lead @ Signal circuit terminal 24 @ Component harness
  8. Ignition - On / Vehicle - In Service Mode
  9. Verify the scan tool parameter: Output Shaft Speed Sensor = 236 to 256 RPM
    • If not between 236 and 256 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.
      • Go to next step: 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.
      • Go to next step: If infinite resistance
    7. Test for less than 2 ohms between the test points: Signal circuit terminal 24 @ 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
    • Go to next step: If between 236 and 256 RPM 
  10. Ignition/Vehicle - Off
  11. Connect the electrical connector.X175 @ T12 Automatic Transmission Assembly
  12. Remove the component: Automatic Transmission Fluid Pan
  13. Disconnect the electrical connector: X177
  14. Ignition - On / Vehicle - In Service Mode
  15. Test for 8.4 to 9.6 V between the test points: 9 V Reference circuit terminal 2 & Signal circuit terminal 1 @ Component harness
    • If not between 8.4 and 9.6 V 

      Replace the component: Automatic Transmission Wiring Harness

    • Go to next step: If between 8.4 and 9.6 V 
  16. Replace the component: B14A Automatic Transmission Output Speed Sensor
scientia non olet · About LEMON Manuals