4.2 Alarm - Mind Of It's Own

[rpaterson]

Hi Folks,

The wife's '02 plate RAV4 has developed 'scared at anything' alarm syndrome. There's no rhyme or reason as to when it goes off, it just sometimes does. It's not necessarily windy when this happens and there's nothing inside the car fluttering about to set off the motion sensors (if it has any?).

Are there any usual suspects that would cause this? I've even switched the courtesy light off permanently in case a door switch is over-sensitive but I don't know if that would actually prevent the alarm sounding. The only thing I can think of is that the Battery charge may be dropping enough to make the car think something untoward was going on. It generally starts OK, but every now and again it struggles and farts a little bit until it catches and fires.

[Big Kev]

Suspect yer Battery richt enough, RP.

Big Kev

[pmb]

I found sometimes on a morning that the hazards would going although a bit dimly. Agree with big kev , how old is the Battery and it might be worth getting the diesel sized one if it's quite old.

[shcm]

Going from memory (about 5+ years back), there is an interior sensor (microwave based) on the 4.2, behind the dash, just below the radio, I think it was.

Don't think it was fitted to every model in the 4.2 range. However, it can be disabled with a 3rd push of fob lock button. You should get an indication of this, with the indicators staying on for a couple of seconds with the 3rd button push.

I suggest trying to disable the interior sensor and see if you still have the problem, before you do anything else. The microwave sensor sensitivity is adjustable.

The old thatham tests required Battery voltage to droop over a long period, without the alarm sounding. perhaps it doesn't comply. I'd be surprised.

[Big Kev]

Even more relevant point from pmb....if it's got that daft wee Battery, bin it for full size one asap.

Big Kev

[Joylove]

Also try unplugging the bonnet switch for a few days to see if things improve. Some cars the sun can heat the bonnet, causing it to flex and the switch makes contact and sets off the alarm.

[anchorman]

When you say you have disabled the door switches, what did you do?

[rpaterson]

Me? Not so much disabling thedoor switches, more just turning off the courtesy light. My thinking being that if a door switch was faulty and bringing the light on, killing the courtesy light may identify that. Prob not.

I know the sun heating the bonnet has nothing to do with the problem because I'm located on the west coast of Scotland and it's September :)

More and more suspecting the Battery. Is the diesel one the same physical size as the petrol one?

[pmb]

More and more suspecting the battery. Is the diesel one the same physical size as the petrol one?

No , it's bigger. Have a search there have been a few threads about this. I found that I had to remove the L brackets that clamp around the top of the Battery and instead of the vertical bars going down the side of the Battery into the base beneath the Battery that they effectively went down the side of the base into different locating slots. HB 072 from Halfords was the one I went for.

edit: corrected battery number

[firemac]

Me? Not so much disabling thedoor switches, more just turning off the courtesy light. My thinking being that if a door switch was faulty and bringing the light on, killing the courtesy light may identify that. Prob not.

I know the sun heating the bonnet has nothing to do with the problem because I'm located on the west coast of Scotland and it's September :)

More and more suspecting the battery. Is the diesel one the same physical size as the petrol one?

Our 02-reg vvt-i performed faultlessly with the original Battery for nearly 10 years including the crap winters of '08/09 & '09/10 despite being parked outside at all times; I only replaced it last autumn for fear of another bitter winter and in deference to its age. I replaced it with a similar one from Toyota that was a good price & came with a 4 yr warranty.

I reckon it will be just fine and saved me the hassle of fitting the bigger diesel item which, depending upon the make, can involve some interesting fun getting the cables & terminal connectors to play.