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Home >> Chevrolet >> 2024 >> Tahoe Commercial, 4WD >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transmission - 10L80 (MHS MHU MQC) - Diagnostic Information And Procedures (2 Of 2) >> Diagnostic Information and Procedures >> DTC P2796-P2799 >> Circuit/System Testing

Circuit/System Testing

    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. NOTE:

    When the following connector is disconnected, the ignition cannot be turned off due to lack of a valid park input to the TCM. If the ignition needs to be turned off, the connector will need to be reconnected.

  2. Disconnect the electrical connector: X1@T12 Automatic Transmission
  3. Test for less than 10 ohms between the test points: Ground circuit terminal 17@X1 (harness side) & Ground
    • If 10 ohms or greater 
    1. Disconnect the ground connection: G103
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 17@X1 (harness side) & G103
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Repair the open/high resistance in the ground connection.
    • Go to next step: If less than 10 ohms 
  4. Verify a test lamp turns On between the test points: B+ circuit terminal 10@X1 (harness side) & Ground
    • If the test lamp does not turn On and the circuit fuse is OK 
    1. Remove - Test Lamp
    2. Test for less than 2 ohms between the test points: B+ circuit terminal 10@X1 (harness side) & Output terminal@X50A
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
    • If the test lamp does not turn On and the circuit fuse is open 
    1. Remove - Test Lamp
    2. Test for infinite resistance between the test points: B+ circuit terminal 10@X1 (harness side) & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistanceIf infinite resistance - Replace the component:
    • Go to next step: If the test lamp turns On 
  5. Disconnect the electrical connector: K71 Transmission Control Module
  6. Ignition - On/Vehicle - In Service Mode
  7. Test for less than 1 V between the test points: Control circuit terminal 18@X1 (harness side) & Ground
    • If greater than 1 V 

      Repair the short to voltage on the circuit.

    • Go to next step: If less than 1 V 
  8. Test for greater than 5 ohms between the test points: Control circuit terminal 18@X1 & Ground
    • If less than 5 ohms 

      Repair the short to ground on the circuit.

    • Go to next step: If greater than 5 ohms 
  9. Test for less than 5 ohms between the test points: Control circuit terminal 18@X1 & The other end of the circuit
    • If greater than 5 ohms 

      Repair the open/high resistance in the circuit.

    • Go to next step: If less than 5 ohms 
  10. Remove the component: Automatic Transmission Fluid Pan
  11. Disconnect the component: G5 Automatic Transmission Auxiliary Fluid Pump
  12. Connect the electrical connector: X1@T12 Automatic Transmission
  13. Test for battery voltage between the test points: B+ circuit terminal 1 & Ground circuit terminal 3@G5 Automatic Transmission Auxiliary Fluid Pump
    • If less than battery voltage 

      Replace the component: Automatic Transmission Wiring Harness

    • Go to next step: If battery voltage 
  14. Test for less than 5 ohms between the test points: Control circuit terminal 4 & The other end of the circuit
    • If greater than 5 ohms 

      Replace the component: Automatic Transmission Wiring Harness

    • Go to next step: If less than 5 ohms 
  15. Test for less than 5 ohms between the test points: Control circuit terminal 3 & The other end of the circuit
    • If greater than 5 ohms 

      Replace the component: Automatic Transmission Wiring Harness

    • Go to next step: If less than 5 ohms 
  16. Refer to: Diagnostic Fault Information & Verify the conditions listed in the table do not exist
    • If a condition exists 

      Repair or replace as necessary

    • Go to next step: If no condition exists 
  17. Test or replace the component: G5 Transmission Fluid Pump - Electric/Auxiliary
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