Security System

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Security System
WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The PASSLOCK™ sensor is powered by circuit 812. The PASSLOCK™ sensor is grounded by circuit 1057. PASSLOCK™ sensor data is supplied to the BCM by circuit 1836.

The PASSLOCK™ sensor data supplied to the BCM is in the form of V-codes or voltage codes. When the proper ignition key is turned in the ignition switch, the correct V-code is supplied to the BCM. The BCM responds by sending a serial data password to the engine controller allowing the engine to run.

The security resistor is bypassed under a tamper condition, possible external magnet applied to sensor. In this mode, a specific V-Code is supplied to the BCM. The vehicle will not start in this mode.

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.