How do you turn the alarm system off on 1990 Astra Estate as just bought it with no manual and has started randomly going off?

To turn off the alarm system on your 1990 Astra Estate, you will need to find the alarm system control module. This is usually located under the dashboard, near the steering column. Once you have found the control module, you will need to press the "off" button. If there is no "off" button, you may need to use a key to turn off the alarm. The key should be inserted into the ignition and turned to the "off" position.

If you are still unable to turn off the alarm, you may need to disconnect the battery. To do this, you will need to open the hood of your car and locate the battery. The battery is usually located in the engine compartment, near the front of the car. Once you have found the battery, you will need to disconnect the negative terminal. This is the black terminal that is marked with a "-". Use a wrench to loosen the nut that holds the negative terminal in place, and then remove the terminal from the battery.

Once the negative terminal has been disconnected, the alarm should be turned off. You can then reconnect the negative terminal and close the hood of your car.