Xc90 won't start

[Mattm63]

Bought this 05 xc90 about a year ago. Has occasionally given the message "alarm system service required" and the sunroof had never worked.. Haven't had any issue with it. but now it won't start. Turn the key, all panel indicator lights come on but it does nothing. Battery good, changed starter, still nothing. Local mechanic checked and said it was related to security system but was dealer only issue.. Read on here about the security battery pack going dead on these models and causing similar issues. Please help? Thx

[oragex]

Welcome to the forum

For the alarm thing, just unplug or replace the siren module (google up). The car and the sunroof should work with the module disconnected (at least the S60 model does so), it's just that when the alarm will be triggered, it won't sound.

If the mechanic suggested replacing the starter, he doesn't really know these cars. This part rarely (if ever) goes bad on this car.

From your explication, I assume when this happens, the engine doesn't crank at all. The first thing to try when this happens, have the ignition key in Pos II (it for electrical safety on this specific car, same thing if you happen to replace or disconnect/reconnect the car battery), then jump start the battery from a running vehicle or with a battery booster. I prefer connecting both battery terminals to the cables, just watch out not to touch the cables to the chassis. See if it starts. It may be as easy as the battery is draining over night because of the melted alarm siren module. The car still has power for all the electrics, but the starter won't have enough power to turn over and crank.

[ggleavitt]

For sure the alarm module can drain the electrical system if the internal batteries have leaked to the point of shorting out the PCB traces within the alarm module itself. That "the sunroof had never worked" is a good indicator that the module is more faulty than just basic alarm functionality. This will need to be replaced, at this point you're better off with another whole module rather than banking on opening the old one up and being able to fix it.

Perhaps the larger question though is how old the battery in this car really is. I suspect if it's not less than 5 years old, you may have 2 separate issues to attend to. If it's the original battery, it may be time for a change unless it's been properly load tested (not just voltage) and has passed.

In the event you have an issue with the battery, can see here for a few links regarding type and size- http://forums.swedespeed.com/search.php ... d=17009322

Good luck !

[Mattm63]

Okay just talked with mechanic again and he said the cem module is probably bad.. He's a local import serviceman. So is there any steps I can take before spending big bucks to have that replaced..?

[ggleavitt]

Might give Xemodex https://xemodex.com/us/products-for-volvo/ a call , see if someone can help with troubleshooting. At a minimum, they can do a rebuild and/or exchange if it's really the CEM.