After having no trouble for a month or so, my friend's 2007 XK wouldn't start the other day after only sitting for 3 days. In trying to determine where the battery drain was I heard that aspirator noise in the instrument panel. It didn't seem to go off so I pulled the fuse. 1. Is that causing a bunch of problems that I'm not aware of? 2. Does the relay that turns that on sometime go bad? And 3. Could it be something else draining the battery? There was also a hum right of the battery near that DVD reader.

Thanks guys!

 

FIRST thing to do is remove the battery, charge it GOOD on a real battery charger of like 10 amps or so, then have it tested. It should hold 12.6 volts after sitting for a good while, and recover from a load.
Try that first and then get back with results.

 

It's a brand new interstate battery manufactured in May. Had Napa test it, they said it was good.

 

The aspirator will make a noise while the car is in convenience mode which starts as soon as you unlock the car or open a door. It stops either around 10 minutes after you turn the ignition off and lock the car or after around 30 minutes if you don't lock the car so if you are hearing it in one of those situations then it is normal.

I always lock my car when I am not using it and that seems to be enough for me to not to have to use a battery maintainer.

 

Even so, you need to make sure yourself that the battery is fully charged. Having a parts store say "it's good" is probably not enough. I am guessing they said that when they sold the battery to your friend at the store. You mentioned it's been a month since then. Leaving the car unlocked, leaving some of the convenience features on, having the doors open or ajar all can drain the battery in an XK. Did he drive the car at all in that time, or just let it sit. Is it parked outside or in a garage? Was the battery on a battery maintainer? Has the battery voltage been measured since purchase?

There are so many factors that could have affected battery health, even in a month, so it's important to get a view of the battery's health today, not a month ago.

 

Thank you. I appreciate your help. Would you know if the aspirator starts back up when you open the car door? Because I let the car sit for more than an hour and when I got back in it it was still running. But don't know if it came on when I opened the door or if that had been running continually.

 

As soon as you pull the door handle everything starts up.

Put the windows down, lock the car and walk away for 45 minutes. Come back and stick your head inside without touching anything.