On my 1997 V70 T5 - The battery went flat, so took it off to charge it. Battery was swollen and did not charge, Time for a new one. I decided to take the opertunity to renew engine vetilation system renewal of pipes, box etc. (been meaning to for a while and had the time now) Oil & filter. New battery put on and all was well. Used Vol-FCR to reset service light. No DTC's Great. Left car overnight and used it today all OK Parked up about 4pm Now tonight at 8pm the alarm goes off, reset and went off again a couple of times. Put Vol-FCR on it and in the Volvo Guard Lock Alarm section, I have 2 DTC's GLA-312 siren internal battery fault Unknown DTC 63 I sort of know about the alarm internal battery, as it has been there before on the last service and has not caused a problem. Does anyone know what the unknown DTC 63 is?

Don't know what the unknown codes is, but were you able to reset both of them?

Hi Chris Yes I reset both codes but they come back after I set the alarm. I think I may have to try and change the internal battery. I have read up on the forums, and it looks as though its located in the inner front wing. Not too clear if battery can be changed or new siren required. If a new siren is required, does it have to be programmed? Bit late to work on car now but I have nothing to loose in getting to siren tommorow to see if battery can be changed. I might disconnect battery to see if anything resets tonight!

All apears to be OK now. I got 4 new AA Ni-Cad batteries with solder tags from Maplin's. Easy job to solder tags and re-fit batteries in siren. Deleted codes and they have not come back yet (fingers crossed) After some searching, it seams the GLA-312 siren internal battery fault, comes up when the siren battery falls below 2.5volts. As I said before, I have had this DTC for some time, at least a year. I am guessing that the Unknown DTC 63, has come up because the siren battery was totaly gone or shorted inside and could not be charged at all. moral of the story is: if you do have a fault on the siren battery, change it or it may come and bite you when you least want it to.

Random False Alarms 

I thought all was good on the car, Passed MOT as well, Emissions were stunning after doing engine ventilation system. Then I sarted getting random false alarms about 3:00am, 9:00am, 6:00pm. I connected up to VOL-FCR several times and could not find any DTC's. Done all the fly spray,coins under ash tray, WD40 on locks thing Took car to Volvo main dealer to find problem. Their reader found GLA-441 Glass Break Sensor had triggered 6 times. Now I got to sort the problem out. I can see the wires going up to the rear side windows to short out. But where is the one on the rear tailgate glass? What is the best way to short thes wires out? ie. pull of press studs and put wire across or strip wire back and join together?

Hi, Don't know if we're on the same wavelength here, but aren't the wires on the rear side windows for the aerial? The glass break sensor on my 850 is on the pillar beside the o/s/f window. David

Hi Talldavey The arial is on the rear side windows as well. It's the three lines top to bottom. Only one side connected. The break glass resistance wire is also connected, where it says "Volvo Guard" there is a little loop. There is also another glass break sensor microphone at the front in the speaker grill. That one would give a different DTC though.

Thanks for that Mike..... I wasn't too sure if the V70 classic was the same though. Kevin I think the glass break sensor plugs into the alarm relay, so the best thing to do may be to disconnect it and see if the alarm goes off again. If it doesn't, it might be worth replacing the sensor. David

850 & V70 alarm systems are very different. The diagrams I have of the V70 system show the two rear side window alarm wires wired in series with the tailgate heater, I've not looked but I would guess the alarm and the actual heater wires are separate on the tailgate glass. If I was making a guess I'd go for the wiring to the tailgate were it flexes as the tailgate is operated. In the tailgate the wire colours for the alarm system are black (earth) and green/yellow (live). The heater wire colours are yellow/read (live) and black (earth).