There seems to be loads of repeated threads on alarms but no FAQs so thought I'd try and match up the advice. Where possible I've linked up other FAQ's to help you find them.

What's covered in this FAQ?

1. Types of alarm problem
2. What sensers the car has
3. How to check if its the Ultrasonics
4. Aftermarket alarm fault codes
5. Part numbers for sirens and ultrasonics
6. Locking and unlocking with alarm and key fob problems
7. LED on with car running

The two types of problem alarm

Alarm + no flashing lights

Knackered siren / siren battery

Alarm with flashing lights

Knackered siren/siren battery
Hyperactive ultrasonics
Problem shut sensors
Voltage drop (main battery)
Voltage drop (siren battery)

Other basic info

Alarm, sensors and what it detects

Ultrasonics = movement in car (can be disabled)

Door sensors
Bonnet sensor
Boot sensor
Voltage drop/tampering with main or alarm battery


First thing I'd check - Ultrasonics

If you have a hyperactive alarm then try setting it with the ULTRASONICS disabled. If it stops going off at random then chances are your ultrasonics are knackered.

To test if they're working then you can set the alarm with the window open, then wave your hand round inside after a minute and it should trigger the alarm, if not your ultrasonics are also knackered (but in a different way)!

The way for setting the alarm with no ultrasonics is set out at post # below.

The part number for the sensers is at post 3 below.

________________________________________

Part numbers

Thanks to "Charlie" for these.

think the part numbers for the ultrasonics are:

Upto 08210 is 6680 00 and they are

________________________________________

LED Stays on while car running and knackered sirens/siren batteries

This is a sign of a knackered / faulty alarm. Most common cause seems to be the alarm syren. There's a FAQ elsewhere for battery replacement.

Note also that there are also cases of a MAIN BATTERY that is failing causing the same symptoms, this is because the alarm batteries charge off the main battery and they are there to back up for main battery disconnection.

Crash Dummy's guide to battery replacement

________________________________________

FAQ'd - Good work Kev and everyone else who contributed

________________________________________

Trackday, trackday, trackday