Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2025TRAILBLAZER ACTIV, FWDREPAIR AND DIAGNOSISBODY & FRAMEIGNITION SWITCH/STEERING LOCKIMMOBILIZER SYSTEMDIAGNOSTIC INFORMATION AND PROCEDURESDTC P1631CIRCUIT/SYSTEM VERIFICATION
2025 Chevrolet Trailblazer ACTIV, FWD
Circuit/System Verification
2025 Chevrolet Trailblazer ACTIV, FWDSECTION Circuit/System Verification
- Verify there are no immobilizer DTCs set in the K9 Body Control Module.
- If any immobilizer DTCs are set in the K9 Body Control Module
Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Go to next step: If no immobilizer DTCs are set in the K9 Body Control Module
- If any immobilizer DTCs are set in the K9 Body Control Module
- Perform the K9 Body Control Module immobilizer learn using the body control module IMMO Function with Existing Transponder or Remote Key in SPS. Refer to Immobilizer System Component Programming .
- Verify the engine starts after the K9 Body Control Module completes the learn procedure.
- If the engine does not start
Perform the K20 Engine Control Module immobilizer learn using the engine control module IMMO Learn in SPS. Refer to Immobilizer System Component Programming .
- Go to next step: If the engine starts
- If the engine does not start
- 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.