Alarm Going Off On Gen 2

[ph47mf]

Hi

I got my first ever problem with my Gen 2 over the weekend. The alarm kept going off a few minutes after every time I lock my car. I know for a fact the doors were closed, windows were shut, rear hatch was shut properly and no mosquitoes or whatever have been upsetting the interior sensors. Without knowing what exactly it was, I took it out for a nice long drive and today it’s been fine. You might think I don’t drive enough, I actually drive it every day, the journey to and from work is about 20 miles in total and it amounts to about an hour of driving every day.

Before I get flamed, I have used the search function and found it could be down to my 12v Battery. My car is 6 years old now and as far as I am aware (I am the second owner) this has not been changed yet (I will look into this at the next service). Could it be any other problem or is it just the 12v?

Any other advice appreciated.

[timberwolf]

A voltage drop in the 12v supply is the most likely cause.

Other possibilities:

Sunglasses in the storage between the sunvisors.

Faulty ultrasonic transducer.

Faulty alarm ecu.

Faulty wiring.

[ph47mf]

No sunglasses in the holder so it might be one of the other three on the list then. Do you think it's covered by the warranty?

[timberwolf]

There wouldn't be any cover left from the original manufacturer's warranty as that was only for 3 years/60K.

Did you get some form of warranty when you purchased the car or that you purchased later?

My experience (not recent) of extended warranties was that they never really offer me peace of mind, because anything that broke on my car was always considered wear & tear - and the list of items not covered always seemed very long.

[Bibsy]

Spooky. My Gen2 exhibited its first fault - exactly the same, alarm going off for no reason - last night. Fine today so far. Perhaps there's something in the air.

Warranty expired - um -day before yesterday. What are the odds?

[Grumpy Cabbie]

One thing that can often set of an alarm OTHER than all those advised above is a front seatbelt retracting itself back into the holder. My gf has a bad habit of leaving about a foot of seatbelt down by the side of the seat, which will then suddenly retract after a few minutes or hours thus setting off the alarm.

The other item which I would seriously consider to be the main issue is the 12v. There are many many threads on this on the Priuschat forum about weird error messages or alarm issues when the 12v starts to fail and you're welcome to google them. The 12v apparantly also fails at about 5 years or 80,000 miles give or take. Most Toyota dealers do a fixed price for them (if I remember correctly) so pop and get it changed. There are after market ones available but they don't have the correct vent holes/tubes or have conversion kits etc.

Let us know how you get on.

[Bibsy]

For my part I coincidentally checked the 12v system only last week (using the diagnostic thing on the touch screen) and it was fine. But I'll check mine again later. It's about the right age/mileage to need replacing if it hasn't been done (no idea so probably not).

I like the seat belt theory, but again, for me, it went off three or four times, so probably not.

I discovered in all of this that you cannot (apparently) leave the car unlocked. It just locks itself eventually whatever you do. I thought about leaving a door physically open (it's in a locked garage) but decided against it. Maybe there's an override for this behaviour in the manual - I didn't look.

[Grumpy Cabbie]

Warranty expired - um -day before yesterday. What are the odds?

If that's the case and you've been getting the car serviced religiously at Toyota then I'd talk to your dealers and appeal to their better nature. Warranty claims just outside warranty are at Toyotas discretion and usually require a full Toyota service history, but if you have those then it costs nothing to ask. Though if it's the 12v I'm sure that'll just be wear and tear.

[Bibsy]

Well, you're right, but just done the diagnostic and it's floating between 11.7 to 12.2 volts, so I've booked it in for a new Battery (and some front wipers) anyway. Peace of mind for my upcoming holiday too.

I'll mention the alarm thing to put a marker down, and then see how it goes. It has just been serviced last week!

Battery wouldn't be under warranty anyway though, even if I'd renewed it at the £680 or thereabouts they wanted for another year. Thanks for the suggestion though.

[timberwolf]

If you unlock the car but dont open a door, I think that is when it will after a delay, lock the car.

[ph47mf]

I bought my car from the stealers last November so I still have a few months of warranty left. Thanks for all the advice but like Bibsy, mine happened no less than 5-6 consecutive times so it shouldn't be factors other than a possible fault within the alarm system itself or a straight forward faulty 12v.

Just how do you bring up the Battery diagnostic screen and at what voltage is deemed healthy and what is deemed ''I better get my ***** down to the local stealers now''?

If you're like me, having troubles with the alarm, I have been locking my car with the key in the key fob to avoid activating the alarm. At work, I am about 10 minutes away from where I normally park my car, there's no way of knowing whether it's going off or not, so it's best to do that or risk it going off all day killing my 12v. That wouldn't be a pleasant way to finish work.

[Bibsy]

True. I thought that too. But tried unlocking, opening a door, shutting it - it locks after a few minutes. Also tried getting in and out, starting and stopping, opening a window and leaving it, everything I could think of - it always locks after either 30 seconds or (undefined) a few minutes.

The only way I can see it to leave the door actually open, making sure no interior lights are on I guess. All good fun!

Edit - crosspost - thanks for the tip about using the keyfob! Should have read the manual after all.

Video on accessing the diagnostic is here. American but works just the same. To add to what he says here, try dropping the windows as well in Aux mode and watch to see if the voltage goes crazy low.

[ph47mf]

Just don't leave your keys in there ^_^

Any ideas about how to bring up the Battery voltage screen?

Is there no other way to source a cheaper 12v Battery than going to Mr T? <_<

[Bibsy]

Video above.

Not sure I'd be happy having other than Mr T do the battery; I'm probably paranoid but for £90 all in and sure it's done right it's worth it to me. I think it's more complex than "an ordinary car", though it might be Toyota frightspeak that's suckered me in.

[ph47mf]

from what i gather, this 12v Battery is just a weirdly shaped normal car Battery, i suspect if i source one somewhere (i can see a few Bosch ones on ebay) i can change it myself for about £50. yes, the savings is not great. let's see what Mr T quotes.

[Grumpy Cabbie]

from what i gather, this 12v battery is just a weirdly shaped normal car battery, i suspect if i source one somewhere (i can see a few bosch ones on ebay) i can change it myself for about £50. yes, the savings is not great. let's see what Mr T quotes.

Pretty much yes. Not having changed mine I dont know exactly but I understand the are conversion kits for the vent tube, unless you don't mind having the Battery venting into the cabin!.

[Sagitar]

Optima do a deep discharge Battery which is a direct replacement for the Prius Battery, but they are expensive.

Look here http://www.optimabatteryshop.co.uk/sc-Optima-Yellow-Top-Batteries-I115.html

There's lots of stuff on the Priuschat site about the advantages of changing to a better Battery than the standard one, but I have no direct experience of the situation.

[ph47mf]

from what i gather, this 12v battery is just a weirdly shaped normal car battery, i suspect if i source one somewhere (i can see a few bosch ones on ebay) i can change it myself for about £50. yes, the savings is not great. let's see what Mr T quotes.

Pretty much yes. Not having changed mine I dont know exactly but I understand the are conversion kits for the vent tube, unless you don't mind having the Battery venting into the cabin!.

I don’t mind it to be honest, unless it’s not bad for the health of the passengers?

[timberwolf]

It's hydrogen so there is a potential for an explosion.

I don't know what risk there is if the vent tube is not connected. Sealed batteries only vent gas as a safety precaution (i.e. the alternative would be to allow the pressure to build and then for the Battery casing to give way). Overcharging is one the cited examples when a sealed Battery will vent hydrogen.

[ph47mf]

A bit of update.

The alarm seems to be back to normal now and it hasn't gone off since that day. It's making me think some external factor might have set it off. Battery has yet to be looked at so basically I don't have a clue about the cause now...

[Grumpy Cabbie]

Had the car been left for a while or used for short journeys? If the 12v hasn't been replaced already then I would ask you to seriously consider getting a repalcement as you WILL start to have weird gremlins and odd error codes popping up.

[Bibsy]

A bit of update.

The alarm seems to be back to normal now and it hasn't gone off since that day. It's making me think some external factor might have set it off. Battery has yet to be looked at so basically I don't have a clue about the cause now...

You know what - nor has mine. And nor do I.

But my Battery is being replaced on Monday - on holiday soon and not risking it.

[Grumpy Cabbie]

But my battery is being replaced on Monday - on holiday soon and not risking it.

Let us know how much it costs all in. Be interesting for those considering replacement.

[Bibsy]

£90 all in, as per the Toyota fixed price thing. All dealers should be the same.

[Grumpy Cabbie]

Thanks for that :)

So £90 fitted for an official Toyota part with warranty that will last another 5 years. Sounds a no brainer to me.

If you're at 5 years old or 80,000+ and on the original Battery it might be prudent to replace it before the winter; or at least if you start to get weird error codes and warning lights, esp if the car had been sat for a few days before hand. £90 is nothing for a genuine part fitted.