XM alarm siren, Alarm siren power source??

[kenhall1202]

My recent ABS problem sorting has involved two fairly long spells with the battery off the car to allow access to the ABS ECU plug. On both occasions when the battery has been reconnected and the engine started the red alarm warning light on the left hand end of the dash switch bank has been permanently lit. Normally this lamp only slowly flashes regularly after the car has been locked and the alarm set using the Plip. The only other time the lamp flashes (more rapidly) is when something has triggered the alarm and this flashing stops when the ignition is turned on.
However after several hours with the battery back on the car, things return back to normal. The owners manual doesn't give an explanation of what the significance is of the warning lamp staying on while the engine runs. The manual does say however that the alarm siren is 'self powered'. Does this mean that the siren has it own independent power source which is kept charged from the main battery?? I'm just curious really!

Ken

[noz]

Hi Ken,

The red light at the left end of the dash indicates if the alarm has been activated during the time when it was set and you left the car. If it has been activated then I think the the number of flashes tells you what set it off (door, bonnet, boot, internal movement detector, car movement detector). After the battery has been disconnected and reconnected the red light comes on and remains on. This would let you know if the would-be thief tried to disconnect the battery in order to steal the car. However, the red light can be reset easily. Turn the ignition off, press and hold the pushbutton to the left of the led and turn on the ignition and the light will go out. Now let go of the pushbutton. This is the reset process for any alarm or battery disconnection.

Cheers

noz

[kenhall1202]

Hi Noz,

thanks for the reply.

I had done the alarm reset procedure as you suggest above immediately after reconnecting the battery. The situation then was:

1. Eveything turned off - red alarm light out. Pressing and holding the alarm button turned the light on to signify that the dash air pressure/volumetric sensors were de-activated.
Pressing/holding the button again turned the light off ie normal behaviour.

2. Turn ignition ON and red alarm light stays off, ie normal behaviour.

3. Start engine and red alarm light comes full on and stays on all the time the engine runs. Pressing the alarm button has no effect. Alarm light goes out when engine stops ie abnormal behaviour. Repeat Plip locking and unlocking + starting and stopping produced the same result.

4. Leave car overnight locked and alarmed. Alarm light flashing slowly as expected.

5. Start engine next morning, alarm light stays off ie back to normal

My question is what happened overnight to the alarm system to cancel the odd behaviour observed in 3. above.

Sorry to be pedantic about this!

Ken

[CitroJim]

That's absolutely bizarre behaviour Ken

[nightmare]

Possibly its an indicator that the siren battery is low/disgharged.

I belive the battery is built into the siren.(It is on the Xantia).

Hope this helps

[kenhall1202]

QUOTE (nightmare @ November 22, 2012 06:36 pm) 

Possibly its an indicator that the siren battery is low/disgharged.

I belive the battery is built into the siren.(It is on the Xantia).

Hope this helps

Many thanks! I think that answers my original question. Obviously the 12 year old battery built into my alarm siren is now a bit tired and becomes low/discharged after several days with the main battery disconnected. I wonder what type of battery it is to last this long.

Ken

[nightmare]

Mine did this a couple of times recently after leaving the key in the ignition overnight.
I also found that the headlights were flashing whilst driving (I heard regular clicking like slow indicator relay)
(My alarm siren is switched OFF via under bonnet switch.)

I found that to reset it I turned off the ignition, locked & deadlocked, then unlocked (with the remote), and everything was OK.

When unlocking your car make sure the indicators flash rapidly,also red alarm led.
If they don't then the alarm is still armed.(sticking relay maybe?)

[kenhall1202]

Update

I accidently set off my alarm recently (several weeks ago) and ever since the LHS red light is permanently lit whenever the engine runs. I reckon the alarm battery is now failing to hold sufficient charge and should be replaced.
Has anyone dismantled an XM alarm unit and identified the type of battery fitted?

Ken

[xmexclusive]

Yes.

They are a pack of wired Nicads cast in something like rigid silicone.
Not too easy to repair and rebuild so used a spare siren.

John