How to Disable a Car Alarm to Change the Battery

Updated March 23, 2017

Many modern car alarms are sophisticated components that tie into the vehicle's ECU (main computer) as well as the ignition system. While cheap, no-name, generic or off-brand alarm systems may only provide a basic siren, more complex systems like Clifford offer multiple zoned proximity sensors, motion sensors, tilt angle sensors and an infrared wireless ignition immobiliser. Since all alarms are designed to prevent theft, you may experience some difficulty trying to disarm them to remove your vehicle's battery without the ignition key.

Insert the key into the ignition.

Turn the key to the "on" or "II" position, and then rapidly turn it to the "off" or "I" position. You may or may not hear an audible disarm warning. The alarm is now disarmed.

Open the bonnet and loosen the retaining nut on the cable clamp with a socket wrench.

Slide the cable clamp off and verify that the alarm is disarmed. If your vehicle has a backup alarm, you will hear the alarm go off. You'll need to reconnect the battery and repeat Steps 1 and 2 to disable the alarm system. You may also need to insert the key into the ignition and start the vehicle for the alarm to be disabled before trying Steps 1 and 2 again.


Your alarm may also require a pass code to disable the alarm. You should consult your car alarm's instruction manual for details.

Things You'll Need

  • socket wrench with socket set
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About the Author

I am a Registered Financial Consultant with 6 years experience in the financial services industry. I am trained in the financial planning process, with an emphasis in life insurance and annuity contracts. I have written for Demand Studios since 2009.