Megane Alarm going off constantly.

Tiny
GEORGEPERKINS
  • MEMBER
  • 1997 RENAULT MEGANE
  • 90,000 MILES
1997 Megane Coupe. Alarm has recently started started malfunctioning (going on and off constantly). I've had to disconnect the car battery to shut it up.The car has its own factory fitted immobiliser controlled by the key FOB, and I can start and drive the car with the alarm sounding. Locking and unlocking the doors isn't stopping the alarm. The alarm sound itself is different to usual - wobbling pitch bird like noise - sounds like it is broken.I haven't changed the car battery recently which I understand can trigger the alarm. Mine is a very similar problem to this: http://www.2carpros.com/questions/renault-megane-1997-renault-megane-how-can-i-stop-the-alarm-on-a-renault-m--2However, I don't have the alarm control in in glove compartment.Is there a way for me to disable the alarm? Cutting wires or removing it altogether is fine as I don't need an alarm anyway. Thanks very much
Friday, March 23rd, 2012 AT 10:31 AM

12 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Is the alarm factory, dealer installed or after market?

I would suggest checking the alarm control module ground circuit connection.
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Friday, March 23rd, 2012 AT 12:35 PM
Tiny
GEORGEPERKINS
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Thank you, not sure if it was factory or dealer, but I believe it is installed by Renault from new.
It is Renault branded Gold shield II or Silver shield II by Sigma.

Could you suggest where I might find the alarm to check the ground connection as I have now experience with Alarms. Do I need to go in from the bonnet or the dash?
Thanks
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Friday, March 23rd, 2012 AT 1:43 PM
Tiny
KHLOW2008
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Our database does not have any information on this vehicle so I am not able to provide you the location of the control module.

Generally control modules are underdash, it can be at the kick panels or under the center console/dash.
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Friday, March 23rd, 2012 AT 2:13 PM
Tiny
GEORGEPERKINS
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  • 7 POSTS
Thanks, I'll try to locate the alarm. If I'm unable to find any obvious connection faults, is it generally safe to cut/disconnect the siren?
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Friday, March 23rd, 2012 AT 2:24 PM
Tiny
KHLOW2008
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That might cause you problrms of battery draining as the alarm is still being triggerred, only the siren is not sounding.
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Friday, March 23rd, 2012 AT 2:43 PM
Tiny
GEORGEPERKINS
  • MEMBER
  • 7 POSTS
OK I found the alarm mounted next to the car battery. Photo attached. I take it the grey cable bolted onto the metal is the ground you are referring to and should be checked to ensure the connection is good. I'll let you know if that works.
Image (Click to make bigger)
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Friday, March 23rd, 2012 AT 8:03 PM
Tiny
KHLOW2008
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It is sitting next to the battery so chances of wire corrosion etc are high. Check the module to see if there is any ket slot. If there is, you can use the key to disarm it. Seems the module is inclusive of siren.
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Friday, March 23rd, 2012 AT 8:26 PM
Tiny
GEORGEPERKINS
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OK thank you, I'll examine all the connections and check for a key hole. I'll do this tomorrow as its dark now. Thanks again and I'll keep you posted.
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Friday, March 23rd, 2012 AT 8:55 PM
Tiny
GEORGEPERKINS
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  • 7 POSTS
Right, it turns out that the box I identified above is just the siren, haven't found the control unit. However I did some research and it turns out that it shouldn't be possible to drive with the alarm active (should be imobilised). This means that in my case the alarm isn't active and the siren is malfunctioning and going off on its own. I opened up the siren and found a 9v backup battery inside. There was a fair bit of corrosion on the battery terminals, so I removed it. I've reassembled the siren and connected the car battery. So far, so goood. Locking and unlocking the doors does sound the usual beeps from the siren. Hopefully the alarm won't sound (I won't be confident until its been quiet for a few weeks.

I'll report back. Thanks for your advice.
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Saturday, March 24th, 2012 AT 3:12 PM
Tiny
KHLOW2008
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You confirmed my suspicions. The backup battery tends to go bad over time and it can also caus battery drain overnight.

Removing the battery should solve the problem of the siren going off on its own.
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Saturday, March 24th, 2012 AT 3:45 PM
Tiny
GEORGEPERKINS
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  • 7 POSTS
OK I'll declare this issue solved. 3 days later and the alarm hasn't played up. Removing the backup battery from the siren solved the issue.
Just to summarise for other people who might encounter this problem:
-Alarm going off randomly - possibly sounding broken/quiet.
-If you can still unlock and start the engine with the alarm sounding - this is an alarm siren malfunction, likely due to a failed backup battery.
-open the siren, possibly mounted near the car battery and remove the small backup battery.

Thanks KHLow2008 for your suggestions.
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Monday, March 26th, 2012 AT 9:11 AM
Tiny
KHLOW2008
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You're welcome and glad to know you have fixed the problem.

Have a great day.
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Monday, March 26th, 2012 AT 12:20 PM

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