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 B3984CIRCUIT/SYSTEM VERIFICATION
2025 Chevrolet Trailblazer ACTIV, FWD
Circuit/System Verification
2025 Chevrolet Trailblazer ACTIV, FWDSECTION Circuit/System Verification
- Perform the Programming and Setup procedure for the control module that set DTC B3984.
- Verify DTC B3984 does not set after programming.
- If the DTC sets after programming
Replace the control module that set the DTC.
- Go to next step: If the DTC does not set after programming
- If the DTC sets after programming
- 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.