Alarm Service Light

[34acd]

After 17 years I started to get "Alarm Service Required" messages in my '01 S80 with which I have had a love/hate relationship since it was new. Love it because it still looks good but hate how difficult it has been to work on when something goes wrong that I can usually fix easily in other cars.

For a couple of months I turned the message off from the turn signal stalk but eventually the alarm itself started to come on for no reason and one time ran down the main battery. I figured the battery in the siren unit had finally failed and finally got to the point of being annoyed enough that I decided to replace it. While there are threads on taking the sealed siren unit apart and replacing the battery I went the easy route and decided to just buy a new unit from my local dealer. $150– a bit high but lower than the listed price.

As usual on this car, getting to everything was a PITA. Drilled out the pop rivets on the front side of the mud guard inside the right front wheel well and was able to peel it back enough after taking off the small metal plate behind the brake caliper to get to the alarm siren. Of course now, exposed, I could only swear at why Volvo would use a tamper-proof bolt to mount it in a completely hidden location but finally managed to slot the head of the bolt with a dremel tool and take it out. Very little clearance around the bolt of course but eventually I managed to back it out. Installing in the new module with a hex-head bolt was then easy and new 3/16" pop rivets got the mud guard back in place.

Since the repair I have been dismayed to get a few more "Alarm System Required" messages and once, the alarm came on by itself again. Is there a short in the system? Maybe. But remembering that resetting the codes in this car could be done by disconnecting the main battery, I thought maybe it was giving me a stored error message which I hadn't cleared.

It seems to have worked. Three weeks later and I haven't had any further alarm service messages and the new siren seems to be working as it should.

[June]

My alarm module is still original in my 2004 S80 T6, but I have had the alarm message and even walked out to find the lights blinking. This only happens when the main car battery is about to go, but is still good enough to start the car normally. It seems if the voltage is a little low at least in my car it causes problems with the alarm system. I do use a factory replacement Volvo brand battery from the dealership in my car. June