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Home >> GMC >> 2023 >> Hummer EV Edition 1 >> 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 OFF and all vehicle systems OFF. It may take up to 2 min for all vehicle systems to power down.
  2. Disconnect the harness connector at the S126 Ride Control Switch.
  3. Test for less than 10 Ω between the ground circuit terminal 5 and ground.
    • If 10 Ω or greater 
    1. Ignition/vehicle 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 10 Ω 
  4. Test for less than 10 Ω between the low reference circuit terminal 3 and ground.
    • If 10 Ω or greater 
    1. Ignition/vehicle OFF, disconnect the harness connector at the K9 Body Control Module.
    2. Test for less than 2 Ω in the low reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • Go to next step: If less than 10 Ω 
  5. Ignition ON/vehicle in service mode.
  6. Verify a test lamp illuminates between the ignition circuit terminal 8 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition/vehicle OFF, remove the test lamp.
    2. Test for less than 2 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is OK and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition/vehicle OFF, remove the test lamp.
    2. Test for infinite resistance between the ignition circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the S126 Ride Control Switch.
    • Go to next step: If the test lamp illuminates 
  7. Ignition/vehicle OFF.
  8. Disconnect the harness connector at the K9 Body Control Module.
  9. Test the signal circuit at the component connector terminal 1 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.
  10. Test the signal circuit at the component connector terminal 1 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.
  11. Test the signal circuit at the component connector terminal 1 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.
  12. Replace the S126 Ride Control Switch.
  13. Operate the vehicle within the conditions for running the DTC. Verify the DTC does not reset.
    • If the DTC resets, replace the K9 Body Control Module.
    • Go to next step: If the DTC does not reset
  14. All OK.
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