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 MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 89 (ENGINE CONTROL SYSTEM SELF-DIAGNOSTICS - 3.1L ENGINE)PROGRAMMINGTHEFT DETERRENT PASSWORD LEARN PROCEDURE10-MINUTE LEARN PROCEDURE
2003 Chevrolet TrailBlazer 4.2 S, 4WD
10-Minute Learn Procedure
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION 10-Minute Learn Procedure
WARNING: This page is about a different car, the 2002 Pontiac Grand Prix, 2002 Chevrolet Malibu, and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
This procedure requires a Tech 2 scan tool and a Techline terminal with current SPS (Service Programming System) software.
- Connect the Tech 2 to the vehicle.
- Select Request Information under Service Programming.
- Disconnect the Tech 2 from the vehicle and connect it to a Techline terminal.
- On the Techline terminal, select Theft Module Re-Learn under Service Programming.
- Disconnect the Tech 2 from the Techline terminal and connect it to the vehicle.
- Turn ignition on, with engine off.
- Select VTD Re-Learn under Service Programming.
- Attempt to start engine, then release key to ON position (vehicle will not start).
- Observe the SECURITY telltale, after approximately 10 minutes, the telltale will turn off (vehicle is now ready to relearn the Passlock™ Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK).
- Turn ignition off, and wait 5 seconds.
- Start engine (vehicle has now learned the password).
- With the Tech 2 (scan tool), clear any DTCs.
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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.