Fault Analysis and Treatment of Car Anti-theft Alarm

Example 1. Fault phenomenon: The remote control of the car anti-theft alarm does not work. When the function buttons of the remote control are pressed, the red LED indicator of the remote control does not light up.
Cause analysis: This fault is mostly in the remote control itself, and there are several situations:
(1) The battery is exhausted;
(2) The positive and negative reeds of the battery are rusted or have poor contact;
(3) The remote control has been exposed to rain or has been soaked in water or oil. In this case, you can remove the circuit board, clean it with industrial alcohol, blow it dry with a household hair dryer or let it dry naturally, and then use it.

Example 2. Fault phenomenon: The remote control distance is getting shorter and shorter, and the LED brightness of the remote control becomes dim or flickers when transmitting signals.
Cause analysis: This phenomenon is mostly caused by insufficient battery power, and the battery can be replaced. In addition, it is recommended not to adjust or replace the components of the remote control by yourself to avoid greater losses.

Example 3. Fault phenomenon: A function key of the remote control fails, and the LED indicator does not light up when the key is pressed.
Cause analysis: The failure of a function key (other function keys are normal) is mostly due to damage to the function key or the solder joint between the key pin and the circuit board is desoldered. Most of the buttons on the remote control are micro switches. When using them normally, you should use light force and pay attention to waterproof, drop-proof and heavy pressure.

Example 4. Fault phenomenon: When the remote control is not in use, the LED indicator often lights up by itself, or the LED indicator lights up as long as the battery is installed, and the remote control does not respond.
Cause analysis: The indicator often lights up by itself when no button is pressed on the remote control. Generally, the buttons of the remote control are mechanically damaged. The performance is that the buttons feel bad and have no elasticity. Replace the buttons. For the code-hopping remote control, there is no response when pressing the function keys of the remote control. After replacing the battery or reinstalling the battery, the LED indicator lights up for 20 to 40 seconds, and then there is no response. This indicates that the button is short-circuited. If the feel is normal, you can use the multimeter R×1 gear to test each button in the circuit, and then replace the short-circuited button.

Example 5. Fault phenomenon: The vehicle automatically shuts down and enters the alarm state after driving for about 30 to 40 seconds. After the anti-theft function is released, the above situation is repeated while driving, and so on.
Cause analysis: This phenomenon is caused by operating the remote control in the car, which causes secondary automatic anti-theft. As long as the anti-theft function key is pressed and the door is opened and closed again, the problem can be solved. The remote control used in the car anti-theft system is limited by the size, and the function buttons are generally no more than four. In this way, each button is often assigned several functions. In a certain state, the same function key controls different functions, or a certain function is completed by multiple buttons. Special attention should be paid when using it.

Example 6. Fault phenomenon: The vehicle is in anti-theft state, and the remote control fails to release the anti-theft function.
Cause analysis: The system is in anti-theft state. Due to the failure of the remote control or the system host (mostly the host has a remote control receiving circuit failure), the anti-theft release fails (the remote control loses control of the system), the car's direction lights (double jump lights) flash, the alarm horn often sounds, and the vehicle cannot start and drive.
At this time, the anti-theft system can only be temporarily removed, which requires the user to pay attention to the general installation position of the anti-theft system host. If the location of the anti-theft device is unknown, you can find the system host according to the LED indicator light, ultrasonic sensor probe or alarm horn and other components of the anti-theft system, and unplug the connector connecting the anti-theft system host to the vehicle. In addition, some remote control car anti-theft alarm system hosts are equipped with an emergency release function, so you can suspend the use of the anti-theft device without removing the system host.

Example 7. Fault phenomenon: The car anti-theft system works normally, the ignition motor runs normally, but the vehicle cannot start.
Cause analysis: This phenomenon may be caused by the alarm or the car's own electrical fault. The judgment method is: short-circuit the two thick wires of the car anti-theft device accessory cut-off ignition relay (12V/30A, generally installed near the car key door). If the vehicle can start at this time, it means that the anti-theft system has a fault, and most of the relays are damaged. If the vehicle still cannot start after short-circuiting the two thick wires of the cut-off ignition relay, it means that the car's own circuit has a fault. In addition, when the vehicle encounters a bumpy road during driving, it is easy to stall or stall instantly. Pay special attention to whether the normally closed contacts of the cut-off ignition relay have poor contact or loose wiring.

Example 8. Fault phenomenon: When the turn signal on one side of the car is turned on, the other side also lights up.
Cause analysis: This fault is caused by the breakdown of the diode that controls the voltage output of the car turn signal (double jump light) of the anti-theft system (these two diodes are inside the host in some models, and attached to the connection line in others). Replace the diode of the same model to eliminate the fault.

Example 9. Fault phenomenon: After entering the anti-theft state, the alarm is triggered immediately. After the alarm is released and the anti-theft state is entered again, the alarm still occurs.
Cause analysis:
(1) The car key is not removed and is in the "ON" position. This is improper operation. Just remove the car key;
(2) The sensor sensitivity is too high or damaged. The sensor can be adjusted or replaced;
(3) The door or front hood or trunk switch is damaged. Among the above situations, poor contact of the door light switch is the most common.

Example 10. Fault phenomenon: The vehicle runs normally, but occasionally it will automatically shut down when opening or closing the door.
Cause analysis: This fault is caused by poor contact of the 12V power supply of the anti-theft system host, and most of the time it is caused by poor contact between the 15A fuse and the fuse holder.

Example 11. Fault phenomenon: The alarm horn does not sound.
Cause analysis: The common cause is that the alarm horn has poor contact with the negative pole of the ground or the horn is damaged. Connect the black wire of the horn lead to the negative pole of the battery and the red wire to the positive pole of the battery. If the horn does not sound, it means that the alarm horn is damaged and can be replaced.