Alarm??

[nuppy]

A friend of mine asked me to look at his C180 yesterday. He is having trouble with is alarm. The rear view mirror has a green and red light in it. Now when he press the key fob the doors lock, indicators flash and both lights flash for about 30 seconds then both go out.. I locked the car with the window, open once the lights stopped flashing i reached in throught the open window and opened the door.. The alarm did not sound. He tells me before only the red light flashed and remained flashing the whole time. I am not familar with this system so any advice on this or information about the correct working of this system would be great.. He told me it has happened in the past and he fount the bonnet open but this time he has checked that

 

[bigasotonuk]

Hi,
Replace fob batteries before doing anything else.
Just because the fob is operating the central locking does,nt mean it is operating the alarm. This happens on mine replace batteries and she is perfect.
If fob batteries make no difference you could try disconnecting and reconnecting the car battery.
Also take opportunity to top-up the charge in the car battery as low battery voltage can cause problems with this type of alarm.

 

[jberks]

The 2 lights flash to indicate a fault. Either that the battery in the remote is low (worth checking first) , or something else is wrong and preventing the alarm from arming, such as a door being ajar.

 

[eddiethemerc]

my red light flashes all the time when i`m driving...Having looked quickly thru the handbook, the alarm is wired thru the radio and sounds when it is removed...My w202 250td doesnt have the original radio fit, it has aKenwood unit fitted. Could itbe that the alarm "sees" this as a fault?

 

[bigasotonuk]

Hi,
Welcome to the forum.
Where is this red light?
In the mirror?
What year is your vehicle?
What type of key has your got?

 

[eddiethemerc]

me?its a w202 c class 250td p reg and yes the lights are in the mirror...i`ve only had "him" since saturday.....always wanted a merc...and now i have one .........YAY!!!!

 

[jberks]

I can't see why the alarm would be connected to the radio. As you say, they were after market units so I can't see how they could be connected reliably.
I can't think why the red light would flash continuously. Its only supposed to flash when the car is locked. Also do be aware that this system doesn't necesarily have an alarm attached - it can be just a central locking system. Assuming all is well and the light flashes all the time, I'd start by disconnecting the battery for 30 mins to reset everything. Before you do, make sure you know how to resync the keyfobs as you will need to do this once you reconnect.

 

[Dec]

my red light flashes all the time when i`m driving...Having looked quickly thru the handbook, the alarm is wired thru the radio and sounds when it is removed...My w202 250td doesnt have the original radio fit, it has aKenwood unit fitted. Could itbe that the alarm "sees" this as a fault?

Just to confirm that it is correct that if you disconnect the radio it will trigger the alarm at least that is the way mine is wired.

Dec

 

[eddiethemerc]

ah.....bugger. I`m not sure how to do that. Its the older style "flip" key and not the later infra red one...does that make a difference? Disconnecting the battery might sort the other fault out to...The abs light is stopping on + cruise control isnt working......either that or i was thinking of just shoving a brake light switch in?