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Home >> Chevrolet >> 2018 >> Impala Premier, Gas >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Automatic Transmission - 6T45 (MHG) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P0851 >> Circuit/System Testing

Circuit/System Testing

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    NOTE:

    You must perform the Circuit/System Verification first.

  1. Ignition OFF, disconnect the X1 Q8 Control Solenoid Valve Assembly harness connector at the automatic transmission.
  2. Install the DT-48616-10  adapter harness to the vehicle harness connector.
    3. NOTE:

    Unless otherwise noted, testing in steps 3 through 9 will be performed at the DT-48616-10  adapter harness connector.

  3. Test for less than 5 Ω between the ground circuit terminal 2 and ground.
    • If 5 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • Go to next step: If less than 5 Ω 
  4. Ignition ON.
  5. Test for 11 - 13 V between signal circuit terminal 3 and ground.
    • If not between 11 - 13 V 
    1. Ignition OFF, remove the harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between signal circuit terminal 3 and ground.
      • If less than infinite resistance, repair the short to ground in the circuit.
      • Go to next step: If infinite resistance.
    3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 Engine Control Module.
    • Go to next step: If between 11 - 13 V 
  6. Ignition OFF, transmission in Park, disconnect the DT-48616-10  adapter harness from the vehicle wire harness.
  7. Install the DT-48616-10  adapter harness to the Q8 Control Solenoid Valve Assembly X1 connector.
  8. Test for less than 10 Ω between the Park/Neutral signal circuit terminal 3 and ground circuit terminal 2 with the transmission in Park and Neutral.
    • If 10 Ω or greater 
    1. Disconnect the DT-48616-10  adapter harness and remove the transmission control valve body cover.
    2. Install the DT-48616-10  adapter harness to the Q8 Control Solenoid Valve Assembly X1 connector.
    3. Disconnect the B15 Transmission Internal Mode Switch electrical connector from the Q8 Control Solenoid Valve Assembly.
    4. Test for less than 10 Ω between Park/Neutral signal circuit terminal 3 and terminal A at the Q8 Control Solenoid Valve Assembly X2 connector.
      • If 10 Ω or greater, replace the Q8 Control Solenoid Valve Assembly.
      • Go to next step: If less than 10 Ω.
    5. Replace the B15 Transmission Internal Mode Switch.
    • Go to next step: If less than 10 Ω 
  9. Test for infinite resistance between the Park/Neutral signal circuit terminal 3 and ground circuit terminal 2 with the transmission in Reverse and Drive.
    • If less than infinite resistance 
    1. Disconnect the DT-48616-10  adapter harness and remove the transmission control valve body cover.
    2. Install the DT-48616-10  adapter harness to the Q8 Control Solenoid Valve Assembly X1 connector.
    3. Disconnect the B15 Transmission Internal Mode Switch electrical connector from the Q8 Control Solenoid Valve Assembly.
    4. Test for infinite resistance between the Park/Neutral signal circuit terminal 3 and ground circuit terminal 2.
      • If less than infinite resistance, replace the Q8 Control Solenoid Valve Assembly.
      • Go to next step: If infinite resistance
    5. Replace the B15 Transmission Internal Mode Switch.
    • Go to next step: If infinite resistance 
  10. Replace the K20 Engine Control Module.
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