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Home >> Cadillac >> 2019 >> CTS Base, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 68 (Automatic Transmission - 8L45 (M5N) Or 8L90 (M5U) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P176B-P176D >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2018 Cadillac CTS. 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 circuit1Terminal 27@Component harness & Ground
    • If less than 8.5 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 circuit1Terminal 27@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 circuit1 Terminal 27@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 9.5 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 circuit1Terminal 27@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 26
    • 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 Intermediate Speed Sensor = 250 to 280 RPM
    • If not between 200 and 300 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 26@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 26@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 26@Component harness & Terminal 15@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 200 and 300 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: B14D Transmission Intermediate 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 circuit1 Component terminal 3 & 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 6
    • Black lead@Ground
    • Set the voltage to 5 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 Intermediate Speed Sensor = 250 to 280 RPM
    • If not between 200 and 300 RPM 

      Replace the component: Automatic Transmission Wiring Harness

    • Go to next step: If between 200 and 300 RPM 
  19. Remove the component: B14D Transmission Intermediate Shaft Speed Sensor
  20. Inspect the following components: Reaction Carrier Assembly - Damaged or misaligned reluctor ring.
    • If a condition exists 

      Replace the component: Reaction Carrier Assembly

    • Go to next step: If no condition exists 
  21. Replace the component: B14D Transmission Intermediate Shaft Speed Sensor
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