vegasjetskier »
I’ve had the persistent “Alarm System Service Required” message and the alarm is inoperative. The lights flash, but no siren. Typically, this means the siren module is bad, so I decided to take a look. Here’s how to pull the module out for replacement. I’m working on a fix for my broken module and if I come up with one I’ll update with that info.
Tools and supplies
- Drill and 3/16″ bit.
- 10mm socket or endwrench.
- 3/16″ X 1/4″ aluminum pop rivets.
- 1) 6mm-1.0 X 10mm hex bolt.
- Pop rivet gun.
- Flat screwdriver.
- Hacksaw or Dremel Tool (not required if you’re just changing the module)
- Spring clamp.
- Adjustable wrench.
- Pin punch or small Phillips screwdriver.
- Hammer.
Procedure
Disconnect the battery negative lead: open the trunk and lift up the back edge of the trunk bottom. Use a wrench to loosen the bolt and remove the two nuts retaining the metal battery holddown bridge:
Slide the bridge slightly to the passenger’s side of the car to free it from the bolt and then lift it out. Lift out the plastic battery cover:
Use a wrench to loosen the nut holding the negative lead to the battery then pull the lead off the battery post:
Wait at least 5 minutes.
Loosen the lug bolts on the passenger’s side front wheel. Chock the wheels on the driver’s side of the car, then jack up the passenger’s side and remove the front wheel.
Drill out the aluminum rivets holding the fender liner to the fender:
These two rivets are toward the top front of the fender well. Look up to see them:
Remove the 10mm nuts holding the metal reinforcement plate to the inside of the wheelwell and remove the plate:
Pull the fender liner loose from the edge of the fender and roll it to the inside of the wheelwell. Use the spring clamp to hold it out of the way. I clamped it to the brake caliper:
If you now look up into the front part of the wheelwell you will see the siren module inside its mounting bracket:
Use a screwdriver to depress the locking tab on the connector, then slide the connector out to the rear:
Apparently Volvo has upped the security on the modules in some of its later model cars: you can’t just loosen some nuts and remove it. I know, I tried. Even if you slide it out the front of the bracket, there is not enough room to get it out between the bracket and the windshield washer tank. I even lowered the tank down and could not get enough room. If you bend the endplate of the bracket out of the way to slide the module out the back, the module is still held in by some plastic tabs on the top and bottom. The solution is to remove the anti-tamper bolt that holds the bracket to the car:
Use the drill to drill a hole at an angle into the anti-tamper bolt head. Due to the shape of the bolt head, the bit will try to skate around a lot, so hold it in position tightly. Make the hole about 3/16″ deep:
Take the bit out of the drill and flip it around. Insert the bit into the hole and use it as a wrench to unscrew the anti-tamper bolt:
Alternatively, you can use a dremel tool to grind off the head of the anti-tamper bolt, remove the bracket, then unscrew the remnants of the bolt with pliers or vicegrips.
Now slide the bracket toward the rear of the car and remove it:
Use the 10mm wrench to loosen the 2 nuts holding the module in the bracket and slide it out of the bracket:
At this point, if you’re just changing the module, reverse the removal steps and skip down to the riveting explanation. You can reuse the anti-tamper bolt or get one with a hex head to replace it. The bolt size is 6mm-1.0 X 10mm if you want to get a new hex bolt. I got 3 of them from Home Depot for 58 cents.
I wanted to see if I could fix my module so I decided to open it up. Using a hacksaw or dremel tool, cut a groove about 1/8″ deep all the way around the module at the line where the black and gray sections meet:
The speaker will come loose from the housing. On mine, it was immediately obvious why it didn’t work anymore. One wire from the battery was disconnected and the circuit board had an accumulation of gunk on it. Apparently the battery had leaked its electrolyte and it had eaten the solder:
I used a knife to cut one end of the plastic battery holddown loose:
Then I lifted up the loose end of the holddown and pulled the battery out:
The battery had apparently leaked its electrolyte out through the seal. I guess that stuff really likes to eat solder. There was no solder left on the end of the black wire.
Research indicates that it is a 2.4V, 240 mAh NiMh battery. I couldn’t find an exact replacement, but there are some other, higher capacity batteries available on the internet that might fit in the space. Here’s one: http://cgi.ebay.co.uk/UNIROSS-600MAH-2- … otohosting If I can get the circuit board to work, I will probably try to adapt one of these batteries as a replacement.
UPDATE
After further investigation, I don’t think it’s a 2.4V battery. I cut the insulation wrap off the old battery and inside I found 3 disk cells (about 1″ in diameter and 3/8″ thick) connected in series. Each disk says 24240, N2H240, B35, and “Made in Germany” on it.
When I did a search a while back, I found a list on the web for the N2H240 that said it was a 2.4V, 240 mAh NiMH battery. If that’s true, then 3 connected in series would yield 7.2V. But, if they are 1.2V cells, then the total output would be 3.6V.
Update 2:38 p.m. EST: OK, I found the specs on the cells (apparently it’s in Swedish, I’m not sure): Tekniske spesifikasjoner: Art.nr 180-4050, Benevnelse N2H240, Diameter 25.20 mm, Høyde 10.20 mm, Info NiMH-Cell, Kapasitet 240 mAh, Spenning 2.40 V; at: http://www.nordicbattery.no/no/products.php?pid=622
So they are 2.4V NiMHs and you will need a 7.2V replacement (since there are 3 hooked in series). There are some available here: http://www.onlybatterypacks.com/items.asp?db=8 for $13 and up, if you want to try replacing the battery yourself.
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I also had some problems with the circuit board. The electrolyte had eaten away the solder holding the connector for the speaker to the board. I will try to resolder the connection and see if the board will work again.
The lowest price I have found on new modules is $149 here: http://www.trademotion.com/partlocator/ … atalogid=0 I’ve heard that if you get it from a dealer it would be about $175 and they charge about $80 for installation. I’ve also heard that you need to have the new module programmed and that you don’t. I don’t know which is correct. I suppose you could install the new module yourself, then take the car to the dealer to have it “programmed” for a fee if it doesn’t work.
Use the pin punch or small Phillips screwdriver to drive the drilled rivet shafts out of the rivet holes.
Installation is the reverse of removal. Once you get the wheelwell liner back in place, use the Pop Rivet tool to set the rivets in the same places that you drilled out the old ones:
Replace the wheel and insert the bolts. Lower the car to the ground and tighten the lug bolts to 103 ft-lbs. Remove the wheel chocks. Reconnect the battery and install the cover and holddown bridge. You’re done!
Hopefully your alarm system now works as normal. If not, take it to a dealer to have the siren module programmed.
UPDATE 2
I tried to resolder the connections on the circuit board but it still didn’t work. I think too much of the circuit copper has been eaten away. I found out the electrolyte from the battery is Potassium Hydroxide, which is very corrosive. So, I’ll have to get a new module. 
I’ll update again after I get that installed.
pritchdog wrote:
“Excellent documentation, I followed your directions and it was exactly as you said. 2001 V70, who knew the siren could control the sunroof, of course, mine quit just before a downpour. I opened the module as you did and found exactly the same thing, I tried to go a little further by removing the transformer from the board and using some tarnish remover to clean the corrosion, in the pictures you can see where the copper was missing. I should have used the conductive product used to repair rear window defrosters to repair the connections but got sloppy and tried to solder jumpers around the breaks. I put the transformer on the wrong side of the board when reassembling and when trying to remove a second time pulled the leads out of the transformer. Moral, have patients if trying to repair the board. Now I’ll never know if it would have worked. New unit installed, works fine. Thanks again”
Project: Replacement/Repair the Siren Module on 2001 Volvo S80 T6
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