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HOMESERVICE MANUALSCHEVROLET2025TRAILBLAZER ACTIV, FWDREPAIR AND DIAGNOSISBODY & FRAMEIGNITION SWITCH/STEERING LOCKIMMOBILIZER SYSTEMDIAGNOSTIC INFORMATION AND PROCEDURESDTC P1649CIRCUIT/SYSTEM VERIFICATION
2025 Chevrolet Trailblazer ACTIV, FWD

Circuit/System Verification

2025 Chevrolet Trailblazer ACTIV, FWDSECTION Circuit/System Verification
  1. Verify there are no immobilizer DTCs set in the K9 Body Control Module.
    • Go to next step: If no immobilizer DTCs are set in the K9 Body Control Module 
  2. Perform the K20 Engine Control Module immobilizer learn using the engine control module IMMO Learn in SPS. Refer to Immobilizer System Component Programming .
  3. Verify the engine starts after the K20 Engine Control Module completes the learn procedure.
    • If the engine does not start 

      Replace the K20 Engine Control Module.

    • Go to next step: If the engine starts 
  4. All OK.
RENDER: 1.0x

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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.