A FAW Volkswagen Jetta partnership car with a mileage of about 270 thousand km in 2004. User reflection: the car's burglar alarm lamp is often bright. Inspection and analysis: the maintenance personnel detected the burglar control unit and found that there was a hint of the anti-theft fault lamp control terminal on the short circuit. The circuit diagram shows that the burglar fault lamp L31 is controlled by foot 6 of the J301. Therefore, the anti-theft control unit connector is disconnected, and the resistance between the pin 6 and the grounding iron on the wire harness side of the connector is measured, and no short-circuit phenomenon is detected. Check the function of L31, also normal. This indicates that the problem is inside the burglar control unit. Troubleshooting: replace the burglar control unit and match the key, troubleshooting.