S40: - Alarm keeps going off at random

bar72 · Mar 5th, 2012, 19:15

hi all, if i lock my 1998 s40 T4 with the fob, the alarm seems to go off at random for around 30 seconds at a time, then it switches off again, does this at random, if i lock it with the key in the door i have no problems but i assume the alarm is not armed? any ideas what couldbe causing it to go off randomly?

tnx in advance

andy_d · Mar 5th, 2012, 19:23

your right lock the car with the key - alarm not set

usual suspect with random alarm is the bonnet switch,, pop bonnet,, find it , the long lever by the bonnet catch, clean it all out, lube it up,, and leaving the bonnet UP , hold the switch closed with fingers, use fob , set alarm , Dont put fob in pocket,, and DO unlock/disarm before letting go of the switch,
if that arms all ok and doesnt go off , check the tab/lever on it meets the catch (bend it out a bit) ,,retest.

if it has No effect at all, check the Door pin switches,, easy to remove, clean / lube/ refit
,,if no joy then do a search on here for the BOOT switch,, n prey it isnt , thats not an easy to get to one

Haizum74 · Mar 5th, 2012, 22:06

Quote:

Originally Posted by andy_d

your right lock the car with the key - alarm not set

usual suspect with random alarm is the bonnet switch,, pop bonnet,, find it , the long lever by the bonnet catch, clean it all out, lube it up,, and leaving the bonnet UP , hold the switch closed with fingers, use fob , set alarm , Dont put fob in pocket,, and DO unlock/disarm before letting go of the switch,
if that arms all ok and doesnt go off , check the tab/lever on it meets the catch (bend it out a bit) ,,retest.

if it has No effect at all, check the Door pin switches,, easy to remove, clean / lube/ refit
,,if no joy then do a search on here for the BOOT switch,, n prey it isnt , thats not an easy to get to one

Beaten to it. That was going to be my suggestion too. If only I knew about it on my last volvo. Would have saved a good few quid.

bar72 · Mar 6th, 2012, 18:48

tnx andy for the info, another job for the weekend

)

yorkipud · Mar 6th, 2012, 21:04

hi mine did this it was the alarm unit its self, they have a built in tamper and a back up battery, the batteries become knacked and so trigger a false attack also if your battery for the car is low/old not holding a charge it can also trigger a false alarm as the unit senses a voltage drop. hope this helps.

960kg · Mar 7th, 2012, 09:29

+1 as above

Mar 5th, 2012, 19:15	#1
bar72 Member Last Online: Jul 27th, 2014 17:59 Join Date: Dec 2011 Location: Cupar View Photos By: bar72	Alarm keeps going off at random hi all, if i lock my 1998 s40 T4 with the fob, the alarm seems to go off at random for around 30 seconds at a time, then it switches off again, does this at random, if i lock it with the key in the door i have no problems but i assume the alarm is not armed? any ideas what couldbe causing it to go off randomly? tnx in advance

Mar 5th, 2012, 19:23	#2
andy_d Premier Member Last Online: Today 01:17 Join Date: Aug 2009 Location: birmingham	your right lock the car with the key - alarm not set usual suspect with random alarm is the bonnet switch,, pop bonnet,, find it , the long lever by the bonnet catch, clean it all out, lube it up,, and leaving the bonnet UP , hold the switch closed with fingers, use fob , set alarm , Dont put fob in pocket,, and DO unlock/disarm before letting go of the switch, if that arms all ok and doesnt go off , check the tab/lever on it meets the catch (bend it out a bit) ,,retest. if it has No effect at all, check the Door pin switches,, easy to remove, clean / lube/ refit ,,if no joy then do a search on here for the BOOT switch,, n prey it isnt , thats not an easy to get to one __________________ 940s - 2l / 92 < gone&missed s401.8 xs auto <gone >V50 2.4SE Geartronic aka "the new money pit" "skyship007 has now been successfully added to your ignore list. "."

Mar 6th, 2012, 21:04	#5
yorkipud Junior Member Last Online: Aug 21st, 2013 16:59 Join Date: Mar 2011 Location: Aberdeen	alarm going off hi mine did this it was the alarm unit its self, they have a built in tamper and a back up battery, the batteries become knacked and so trigger a false attack also if your battery for the car is low/old not holding a charge it can also trigger a false alarm as the unit senses a voltage drop. hope this helps.

Mar 7th, 2012, 09:29	#6
960kg Premier Member Last Online: Dec 28th, 2022 12:25 Join Date: Jun 2009 Location: Mercville	+1 as above __________________ Mercedes C320CDI Sport Estate 3 litre V6 7 Gear Auto Remap 290bhp 628Nm torque @ 1600revs 45.1mpg

Mar 6th, 2012, 18:48	#4
bar72 Member Last Online: Jul 27th, 2014 17:59 Join Date: Dec 2011 Location: Cupar View Photos By: bar72	tnx andy for the info, another job for the weekend )

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