The alarm will sound as soon as you remove the PIR cover, go to the alarm key pad and enter your code. The alarm will be showing anti tamper but the alarm should stop sounding. Remove the old PIR after taking note of the supply, NC & TMP circuits. Replace the sensor, wire it up, replace the PIR cover and then press the reset key on your alarm pad. The 24HR tamper light should then go out.
Les, August 2009