V70: Electrical VIDA Reading off alarm cause - help!

[Stu B]

Originally Posted by dlb

Thank you Stu! I have exactly the same issue and will see if I can replace the battery to fix the siren. When you say the siren is to the left of the main battery, do you mean near side or offside ( mine is a RHD 2015 XC70 UK version) and is there any chance you can post a photo of its location and a little on how you got it out?

Hi, I did take a few photos and will add them when I get chance. The siren is mounted to the bulkhead on the passenger side of the car, just under the scuttle panel that the wiper arms pass through.

I removed the wiper arms, then that plastic panel which has around 6 plastic clips and a rubber strip holding it in place. With that lifted you will see a black vented cage item to the left of the main battery looking from the front of the car into the engine bay.

It’s a fiddle to get out and there are several sharp edges so be careful and wear gloves. The electrical plug unclips and you can remove the siren with cage part attached from the bulkhead bracket and take it out of the car.

Mine has been quiet (no hazard flashes or dash errors either) and behaving for over a week now since replacement. I think the interior sensors error is a red herring perhaps as the siren playing up had previously caused a few unexpected alarm triggers on cold evenings. Fingers crossed!

Thanks
Stu

[Stu B]

https://i.imgur.com/gJCj51u.jpg

https://i.imgur.com/gvtFRIH.jpg

Hopefully this works, I can’t resize the images easily from an iPhone so just adding links.

[dlb]

Thank you. Well that explains a lot - the siren in my car is not there! Ill have another look behind the wheel arch covers… Very odd!

[dlb]

Just found my siren. It wasn’t under the scuttle cowl but was above and behind the front left wheel. Easy to get to by removing the wheel and mud guard, electrical connection removed by inserting a small flat head and levering up the clip

[Stu B]

Originally Posted by dlb

Just found my siren. It wasn’t under the scuttle cowl but was above and behind the front left wheel. Easy to get to by removing the wheel and mud guard, electrical connection removed by inserting a small flat head and levering up the clip

Well found! If you crack it open see what the battery looks like as mine was soldered into the PCB so I didn’t bother replacing that and just swapped the whole siren for a newer secondhand unit. If the battery unplugs it might be an easy swap to just replace that as per previous advice on here and YouTube videos.

[Tatsfield]

It's not difficult to unsolder and replace the battery on the PCB but you do need a replacement battery of the same type with the same solderable pin configuration. Batteries with leads should be easier but you may not be able to get one with the same connector so you may be cutting and soldering the connector from the old battery to the new one. However over £100 saving against a new one is a worthwhile incentive.

The problem with second hand siren units is that Varta give a life to their battery of 6 years and second hand the battery is likely to be well into that so it will fail relatively quickly. The reason that DIY owners buy second hand siren units is when their own has a destroyed PCB they can fit a new battery to a second hand unit that has a good circuit board and still save £70 to £80 on the repair. If your siren has a good circuit board you don't need a second hand one and can fit a new battery to your own unit.

You've done the hard part; you found the damn thing!

[dlb]

I opened the siren (metal type) by a quick grind on the spot welds and a tap with a punch. Jimmied the plastic siren out, cracked it open by tapping around the seam with a knife and replaced the 2 x aaa cordless phone type batteries with new ones. I had to splice the cables as I couldn’t match the connector.

I now have silent alarms with flashing hazard lights and still have the Alarm System Service Required error message. Could this be an internal sensor issue?

[Kev0607]

Originally Posted by dlb

I opened the siren (metal type) by a quick grind on the spot welds and a tap with a punch. Jimmied the plastic siren out, cracked it open by tapping around the seam with a knife and replaced the 2 x aaa cordless phone type batteries with new ones. I had to splice the cables as I couldn’t match the connector.

I now have silent alarms with flashing hazard lights and still have the Alarm System Service Required error message. Could this be an internal sensor issue?

What was the condition of the circuit board inside the siren?

Replacing batteries if the circuit board is all corroded is pointless.

[Stu B]

Originally Posted by dlb

I opened the siren (metal type) by a quick grind on the spot welds and a tap with a punch. Jimmied the plastic siren out, cracked it open by tapping around the seam with a knife and replaced the 2 x aaa cordless phone type batteries with new ones. I had to splice the cables as I couldn’t match the connector.

I now have silent alarms with flashing hazard lights and still have the Alarm System Service Required error message. Could this be an internal sensor issue?

When I was researching this and reading various posts on here, I noticed one poster who said it took a while after the siren was reconnected (with a good battery) before the warning message disappeared from the dash. Maybe just leave it a while and see if it resets and starts to behave?

This is assuming the circuit board looks good as Kev says of course.