Alarm problem - help please

This morning I visited my car and noted that the alarm was set but there was an intermittent 'ping' sound. I unlocked the car and checked all doors etc. I re-set the alarm and after a few moments the sound started again. I even locked the car with the key and did not set the alarm; again that pinging sound [every few seconds] started. Does anyone know or understand what has gone wrong and how can I sort it out? PS I am a real non-techie so I need all the help I can get - short of taking the car to a garage.

Locking the car with the key still sets the alarm. Are you getting any beeps on locking? Is the carpet wet under the passenger seat? Take a look at the LED in the front of the windscreen when you lock the car. It should rapid-flash for a few seconds, before settling down to a single-flash every 2 seconds or so. If you are getting a double-flash, there is an alarm system fault. A diagnostic check is the only way to tell what's going on.

Sounds like a problem with the Sonar module.... Seriously I've never heard of a pinging noise before - Looks like a trip to Cambridge is in order Julian [&o]

With top guys like Richard & Mark on the case, all I can add is the obvious...... check that the boot, bonnet, centre consul cubby box are all opened & fully re-closed to be sure that you aren't getting the warning beep because one isn't fully secured!

As above: It's often the centre cubby box.

But surely something left open (such as cubby box) would only cause a single or double beep, not an on-going ping noise ? I'd go with Mark's diagnosis of the sonar. Anyway, let us know when you find what it is.

The only pinging I ever hear is when you don't put your seatbelt on above ~5mph or if the lights are on. Could one of those circuits be damaged?

Thanks folks. It is an ongoing pinging sound. A single ping every 30 seconds or so. I have checked everything I can touch, feel, see or hit. Makes no difference. Off to Cambridge this morning to drop the car off for check and possible re-setting of the alarm. I cannot leave it in a residential area - I have had complaints already. Will report more later. Once again, my thanks to you all for your suggestions.

Did you check the LED flashes? Wet carpet? If it was flashing properly, I would suspect the tilt sensor or siren, which don't always show a system fault on the diagnostics. The 'ping' sound might be coming from the siren. I had a 'double-ping' on locking when the tilt sensor on my C2 was full of water.

Ah! Its the machine that goes 'ping' from Monty Python ... http://www.youtube.com/watch?v=arCITMfxvEc

Thanks everyone for your help. Took the car to the OPC in Cambridge. The alarm sensors were not working and the unit had to be replaced. All is now relatively harmonious in the car. The only problem surrounds the radio - after the cigarette lighter socket was repalced some time ago, the radio fascia lights stopped working and the multi-CD unit cannot work. I fear that something is shorting something else - if I use my TomTom conected via the cigarette socket the radio goes fuzzy or silent. However, to investigate this will cost me a lot - so I make do without a fully working radio. Again, my thanks for your suggestions - PCGB is a friendly and helpful club!

Glad you got the alarm sorted, Julian. However, I think you should get that 997 cab you were looking at................[ ] (before anything goes wrong![&:])