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Home >> Chevrolet >> 2021 >> Trailblazer ACTIV, FWD >> Repair and Diagnosis >> Body & Frame >> Body, Cab Control Systems >> Secondary And Configurable Customer Controls >> Diagnostic Information and Procedures >> Drive Mode Switch Malfunction >> Circuit/System Testing
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Circuit/System Testing

  1. Ignition/Vehicle OFF, disconnect the harness connector at the S48E Multifunction Switch - Center Console.
  2. Verify a test lamp illuminates between terminal 1 and B+.
    • If the test lamp does not illuminate 

      Repair the open or high resistance on circuit 351 or the ground point for circuit 351.

    • Go to next step: If the test lamp illuminates 
  3. Ignition ON/Vehicle in service mode, test for 4.8 V - 5.2 V between 5 V reference circuit terminal 15 and ground.
    • If less than 4.8 V 
    1. Test circuit 4109 for a short to ground.
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Test circuit 4109 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found.
    3. Replace the K20 Engine Control Module.
    • If greater than 5.2 V 
    1. Test circuit 4109 for a short to voltage.
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found.
    2. Replace the K20 Engine Control Module.
    • Go to next step: If between 4.8 V - 5.2 V 
  4. Ignition/vehicle OFF, disconnect the X2 connector at the K20 Engine Control Module.
  5. Test for infinite resistance between signal circuit terminal 17 and ground.
    • If less than infinite resistance 
    1. Test circuit 4108 for a short to ground.
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Replace the S48E Multifunction Switch - Center Console.
    • Go to next step: If infinite resistance 
  6. Ignition/Vehicle off, connect the S48E Multifunction Switch - Center Console.
  7. Press and hold the S48E Multifunction Switch - Center Console.
  8. Test for less than infinite resistance between signal circuit terminal 17 and ground.
    • If infinite resistance 
    1. Disconnect the harness connector at the S48E Multifunction Switch - Center Console.
    2. Test signal circuit 4108 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found.
    3. Replace the S48E Multifunction Switch - Center Console.
    • Go to next step: If less than infinite resistance 
  9. Replace the K20 Engine Control Module.
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