My 2006 Volvo S40 would occasionally make a loud noise coming from the engine compartment when being turned off. When I would try to restart the car it wouldn't restart. 30 minutes later it would. That noise eventually stopped but my car now needs to be jump started daily. Click click sound when jump starting. It's not the battery though. More often than not it says alarm system service required. But then it goes away at other times. What could it possibly be?

Thank you

 

Welcome to the forum!

Holy cow, it sounds like you have a serious electrical issue somewhere. Now I have not read of another similar problem like yours so I'm betting you have an engine component with an internal short. If you know how to use a multimeter then you can try to isolate the item draining your battery. (Given the loud noise after you turned off the engine I might suspect the radiator fan.) Methods to trace a short include pulling the fuses while watching the drain on the battery. This usually narrows the search down quite a bit as normally there are several circuits on each fuse. Once you have the search narrowed, start disconnecting individual pieces on that circuit until you find the problem.

Sorry I couldn't be more specific. Let us know how it goes?

 

If the 06 S40's alarm is the same set up as the S60s, then I'd look into the alarm battery. Some models have an internal battery in the alarm box (I suppose to keep the alarm active in case your main battery drains). Seems to me, if this battery shorts, it could also drain the main battery to the point it can't start the car. Worth a google to see if you can find any posts on the alarm battery topic. Similarly if the alarm battery fails, it may trigger the immobilizer in the car.