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Home >> Chevrolet >> 2018 >> Suburban 3500 HD LT >> Repair and Diagnosis >> External Pages >> Different car >> Section 21 (Automatic Transmission - 10L80 (MF6) - Diagnostic Information And Procedures) >> Diagnostic Information And Procedures >> DTC P176B, P176C, P176D, P178F Or P17D3: Intermediate Speed Sensor >> Circuit/System Testing

Circuit/System Testing

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  1. Ignition/Vehicle & All vehicle systems - Off
    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.
  2. Disconnect the electrical connector: X1 @ T12 Automatic Transmission Assembly
  3. Ignition - On / Vehicle - In Service Mode
  4. Test for 8.3 to 9.6 V between the test points: 9V Reference circuit terminal 7 & Ground
    • If less than 8.3 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector:K71 Transmission Control Module
    3. Test for infinite resistance between the test points: 9V Reference circuit terminal 7 @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: 9V Reference circuit terminal 7@ 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 9.6 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 1V between the test points: 9V Reference circuit terminal 7 @ Component harness & Ground
      • If 1V or greater - Repair the short to voltage on the circuit.
      • If less than 1V - Replace the component:K71 Transmission Control Module
    • Go to next step: If between 8.3 and 9.6 V 
  5. Ignition/Vehicle - Off
  6. Install the special tool: EL-38522  Variable Signal Generator
    • Set the voltage to 5 V
    • Set the frequency to 300 Hz
    • Set the duty cycle to 50 %
    • Black lead@Ground
    • Red lead@Signal circuit terminal 2
  7. Ignition - On / Vehicle - In Service Mode
  8. Verify the scan tool parameter:Transmission Intermediate Speed Sensor 1 = 351 to 371 RPM
    • If not between 351 and 371 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 2 @ 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 2 @ 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 2 @ Component harness & Terminal 13 @ 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 351 and 371 RPM 
  9. Ignition/Vehicle - Off
  10. Connect the electrical connector: X1 @ T12 Automatic Transmission Assembly
  11. Remove the component:Automatic Transmission Fluid Pan
  12. Disconnect the electrical connector:B14DA Transmission Intermediate Speed Sensor 1
  13. Ignition - On / Vehicle - In Service Mode
  14. Test for 8.3 to 9.6 V between the test points: 9V Reference circuit terminal 2 & Ground
    • If not between 8.3 and 9.6 V 

      Replace the component:Automatic Transmission Wiring Harness

    • Go to next step: If between 8.3 and 9.6 V 
  15. Ignition Off
  16. Install the special tool: EL-38522  Variable Signal Generator
    • Set the voltage to 5 V
    • Set the frequency to 300 Hz
    • Set the duty cycle to 50%
    • Black lead@Ground
    • Red lead@Signal circuit terminal 1
  17. Ignition - On / Vehicle - In Service Mode
  18. Verify the scan tool parameter:Transmission Intermediate Speed Sensor 1 = 351 to 371 RPM
    • If not between 351 and 371 RPM 

      Replace the component:Automatic Transmission Wiring Harness

    • Go to next step: If between 351 and 371 RPM 
  19. Test or replace the component:B14DA Transmission Intermediate Speed Sensor 1
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