Common fault analysis and solutions of automobile anti-theft alarm

The use of automobile anti-theft alarm system is achieved by the use of automobile power supply and some circuits of the automobile itself. Once the anti-theft device fails, it will affect the normal use of the vehicle. This article analyzes the causes of some common faults and introduces treatment methods. Most of the faults can be resolved by users.

Example 1. Trouble phenomenon: The remote control operation does not work. When pressing each function button of the remote control, the red LED indicator of the remote control does not light.

Reason analysis: This failure is mostly in the remote control itself, there are the following 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 is exposed to rain or water. Water, oil immersion, etc. In this regard, the circuit board can be taken out, washed with industrial alcohol, blown dry with a household electric hair dryer or allowed to dry naturally before it can be used.

Example 2. Failure phenomenon: The remote control distance becomes shorter and shorter. When transmitting a signal, the LED brightness of the remote control becomes dark or flickers.

Reason analysis: This phenomenon is mostly due to insufficient battery power, just replace the battery. In addition, it is recommended not to adjust or replace the components of the remote control by yourself, so as not to cause greater losses.

Example 3. Failure phenomenon: a function key of the remote control is invalid, and the LED indicator does not light when the key is pressed.

Reason analysis: a function key fails (other function keys are normal) mostly because the function key is damaged or the solder joint of the key pin and the circuit board is unsoldered. The buttons of the remote control are mostly micro switches, which should be light in normal use, and pay attention to waterproof, anti-drop and heavy pressure.

Example 4. Failure phenomenon: When the remote control is not used, 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.

Reason analysis: The indicator light often lights up when the remote control does not press the button, which is usually the mechanical damage of the remote control button. It is shown that the buttons do not have a good feel and have no flexibility. Just replace the buttons. For the code-hopping remote control, there is no response to pressing the function keys of the remote control. After replacing the battery or reinstalling the battery, the LED indicator lights for 20 to 40 seconds, and then there is no response. This shows that the keys have short-circuit damage. If the hand feels normal, you can use the multimeter R × 1 to test each key on the road, and then replace the short-circuited keys.

Example 5. Failure phenomenon: The vehicle will automatically turn off and enter the alarm state after driving for about 30 to 40 seconds. After releasing the anti-theft function, repeat the above situation while driving, and so on.

Reason analysis: This phenomenon is caused by operating the remote control in the car, causing 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 for car anti-theft system is limited by the volume, and the function keys are generally not more than four, so that each key is often given several functions. In a certain state, the function controlled by the same function key is different, or a certain function consists of many It is necessary to pay special attention when using the buttons.

Example 6. Trouble phenomenon: The vehicle is in the anti-theft state, use the remote control to cancel the anti-theft failure.

Reason analysis: The system in the anti-theft state, due to the failure of the remote control or the host of the system (the host is mostly the failure of the remote control receiving circuit), the anti-theft failure is canceled (the remote control loses control of the system), and the car's direction light (double jump lights) flash 3. The alarm horn often sounds and the vehicle cannot start driving. At this time, the anti-theft system can only be temporarily removed, which requires users to pay attention to the general installation location of the anti-theft system host. If you don't know the location of the anti-theft device, you can find the system host according to the anti-theft system's LED indicator, ultrasonic sensor probe or alarm horn and other components, unplug the anti-theft device host and vehicle connector. In addition, some remote control car anti-theft alarm system hosts are equipped with an emergency release function, and the use of anti-theft devices can be suspended without removing the system host.

Example 7. Trouble phenomenon: The automobile anti-theft system works normally, the ignition motor runs normally, but the vehicle cannot start.

Reason analysis: This phenomenon may be caused by the alarm or the electrical failure of the car itself. The judgment method is: cut off the two thick wires of the ignition relay (12V / 30A, generally placed near the car key door) of the car anti-theft device accessory. If the vehicle can start at this time, it means that the anti-theft system is faulty, and most of them are relays. damage. If the two thick wires of the ignition relay are shorted and the vehicle still fails to start, it means that the car's own circuit is faulty. In addition, when the vehicle encounters bumpy roads during driving, it is easy to turn off or instantaneously turn off. Special attention should be paid to whether the normally closed contact of the cut-off ignition relay has poor contact and loose wiring.

Example 8. Trouble phenomenon: When turning on the car, the turn signal is on, the other side is also on.

Reason analysis: This failure is the breakdown of the diode that controls the voltage output of the car's direction light of the anti-theft system (some models have these two diodes inside the host, and some are attached to the connection). Replace the same type of diode to eliminate the failure.