I have a mystery that 3 garages have not been able to solve If I lock my car (using an actual key) the flashers come on in 5 minutes, no siren tho. They stop when I unlock the car. If I lock it by pushing the inside door lock button they do the same, even when I unlock the driver's door by hand before closing. They continue blinking for hours then shut off. I cannot keep putting $ in to solve a phantom problem they can't identify. One suggestion was take it to Volvo to switch out each door lock.Umm, no. Anyone have any suggestions other than that? Has anyone else ever had this issue?? TIA, I love this car

 

A problem such as that on a car that old is not going to be top priority at any shop. There are many shops that won't work on a car that old. The alarm - on newer Volvos you can use a scan tool to determine the cause of the alrm. Not so on your car. Your car will require a guess and check method - trying to test erratic continuity problems.

I think I would first test the alarm to verify the alarm siren and or horn does not work. I'm familiar with the alarm horn 16/19 mounted on the firewall, they fall apart. Don't know about the alarm siren that has a horn picture in it #16/35. Roll window down, lock car, wait, reach in and open door - lights should flash and alarm should sound. So then let's guess that something is setting the alarm off and the siren/horn does not work. In each door and tailgate built into the latch assemblies is a microswitch that tells the lock/alarm module 2/76 that door is closed. One of those could be the problem - they will need to be eliminated and tested one at a time. On the Central locking diagram those are built into 3/100, 3/110, 3/76, 3/77, and 3/78. By the way as of about 10 years ago some of those inner door latch assemblies were no longer available new, and my large Volvo only junkyard does not have any. Other sensors can set off the alarm. On the Alarm page there is a hood switch 3/62, a tilt sensor 7/100, and there could be glass break wires in the cargo windows 7/135, 7/136, as well as a glass breakage microphone and sensor 7/101, 7/102 and 7/96 and 7/97 left and right movement sensors.

So you can see there is a lot to check, one part at a time - and I understand why 3 shops have not solved your problem. There's a brake job or a service on another car that gets done, they get paid and move onto the next car - Ignoring the 25 year old Volvo that was build maybe about the time they were born and might be the only one they have ever worked on.

This is probably only going to get fixed by you - no shop is going to invest the time needed. (unless you give them unlimited funds up front, and there is still no guarantee they will be smart enough to figure it out.)

What would I do? Probably disconnect the hood switch 3/62 on the left side of the core support and see if the problem happens. It's maybe the easiest part to get to and I have seen many disconnected. The next place would probably be the drivers door latch assembly - that's the one that has been used the most and as mentioned earlier is not available. If the door microswitches provide a ground when closed (telling the alarm it's ready to arm) you might be able to bypass the offending switch and permanently ground that wire . The lock/alarm module 2/76 might be modified to negate the alarm function - I'm guessing you might be happy just to be able to lock the car.

 

Thanks for all the info. I was going to try the micro switches next and the alarm battery stack, but thought I'd check here for more ideas The garage I took it to last works on antique cars, vintage and just plain old cars. I gave them a limit for $ and they did try and trace it. And yes, just being able to lock the car is my objective, especially since I work at a jail. Don't want any extra baggage when I come out from work I was even thinking about a kill switch as a last resort. You've given me a lot of great info to work from. Thanks again