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HOMESERVICE MANUALSCHEVROLET2025SUBURBAN LS, 4WDREPAIR AND DIAGNOSISBODY & FRAMEBODY, CAB CONTROL SYSTEMSSECONDARY AND CONFIGURABLE CUSTOMER CONTROLSDIAGNOSTIC INFORMATION AND PROCEDURESDRIVE MODE SWITCH MALFUNCTIONCIRCUIT/SYSTEM TESTING
2025 Chevrolet Suburban LS, 4WD

Circuit/System Testing

2025 Chevrolet Suburban LS, 4WDSECTION Circuit/System Testing
  1. Ignition/vehicle OFF, disconnect the harness connector at the S126 Ride Control Switch.
  2. Disconnect all components that share the low reference circuit 1449 with the exception of the K9 Body Control Module.
  3. Verify a test lamp illuminates between the low reference terminal 3 at the S126 Ride Control Switch and B+.
    • If the test lamp does not illuminate 
    1. Test circuit 1449 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.
    2. Test circuit 1449 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.
    3. Test circuit 1449 for a short to ground after disconnecting the K9 Body Control Module.
      • 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.
    4. Replace the K9 Body Control Module.
    • Go to next step: If the test lamp illuminates 
  4. Ignition ON/Vehicle in service mode, test for 4.8 V - 5.2 V between the 5 V reference circuit terminal 1 at the S126 Ride Control Switch and ground.
    • If less than 4.8 V 
    1. Test the signal circuit 2203 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 2203 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 K9 Body Control Module.
    • If greater than 5.4 V 
    1. Test circuit 2203 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 K9 Body Control Module.
    • Go to next step: If between 4.8 V - 5.4 V 
  5. Test or replace the S126 Ride Control Switch.
  6. 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 
  7. All OK.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.