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Home >> GMC >> 2024 >> Terrain SLT, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 6 (Automatic Transmission - 6T40 (MNH) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P171A-P171C >> Circuit/System Test

Circuit/System Test

WARNING: This page is about a different car, the 2024 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:

You must perform "Circuit/System Verification" first.

  1. Ignition OFF, disconnect the harness connector at the B280 Automatic Transmission Accumulator Solenoid Valve. Ignition "ON".
  2. Verify a test lamp illuminates between the ignition circuit terminal 1 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Turn the ignition OFF.
    2. Test for less than 2 Ω in the ignition voltage circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If the measured resistance is less than 2 Ω, see DTC P0685-P0687, P0689, P0690 or P1682.
    • If the test lamp does not illuminate and the circuit fuse is open 

      An open fuse will cause other DTCs to set. Diagnose any other DTCs first.

    • Go to next step: If the test lamp illuminates 
  3. Connect a test lamp between the ignition circuit terminal 1 and the control circuit terminal 2.
  4. Engine idling, transmission in Park.
  5. Verify the test lamp turns ON and OFF when commanding Autostart/stop Stop and Start commands with a scan tool.
    • If the test lamp is always Off 
    1. Ignition OFF, disconnect the harness connector X1 at the K20 Engine Control Module, Ignition ON.
    2. Test for less than 1V between the control circuit and ground:
      • If 1V or greater, repair the short to voltage on the circuit.
      • Go to next step: If less than 1V.
    3. Turn the ignition OFF.
    4. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open /high resistance in the circuit.
      • If less than 2 Ω, replace "K20 Engine Control Module".
    • If the test lamp is always On 
    1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If the circuit is not short to ground, replace the K20 Engine Control Module.
    • Go to next step: If the test lamp turns On and Off 
  6. Test the B280 Automatic Transmission Accumulator Solenoid Valve. Refer to Component Testing.
    • If the solenoid valve does not pass 

      Replace the B280 Automatic Transmission Accumulator Solenoid Valve.

    • Go to next step: If the solenoid valve passes 
  7. Replace the K20 Engine Control Module.
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