2006 2.5T battery draining overnight Topic is solved

[TrstnBrtt]

I have a 2006 XC90 that keeps dying overnight and sometimes while it’s parked while I’m at work. I replaced the battery thinking that was the problem but it still went down. I finally got around to getting a multimeter on it between the negative battery post and negative battery lead to try and find a parasitic drain. When I pulled fuse 2 beside the steering wheel (30A, Amplifier) it dropped from 2.XX A to .02 A. When I plugged the fuse back in there was an Audiable crack and I could hear a very faint hum coming from the speaker (I wouldn’t have heard it on it’s own but my head was right beside the speaker. A bit of background I’ve owned this car for like 4 years and when I first got it I was able to swap out the 2006 style radio for the 2007+ radio to gain AUX (please note that I do not have satellite radio as an option, but I know there is a TSB for Sirius draining the battery.) but the battery has only been going flat for the last few weeks, I didn’t have any problems before. About 2 years ago the sunroof drains plugged up and there was quite a lot of water under the passenger seat, but I can’t remember if the amp got wet. I’m wondering if this test I did to find the draw would be accurate or if I should keep worrying. I closed the door latches and locked the car with the reduced guard on for 10-15 minutes to put the modules all to sleep (?). Should my next step be to replace the amp?

[RickHaleParker]

Disconnect the amp and measure. It could be in the harness.

[TrstnBrtt]

Disconnect the amp and measure. It could be in the harness.

Oooh good idea. I’ll give it a try today!

[oragex]

You don't need to lock the doors for a drain test, just serial plug the multimeter to the battery, leave it on then wait 10 minutes. Pretty much everything shuts down - may want perhaps to remove the alarm siren fuse to be sure. Only my trunk lights refuse to go off at 10 min so I usually disconnect them too. At sharp 10 min after touching the car you should see the amps dropping to 0.01-0.02 if there's no drain - but keep in mind if a module has a short it may also act up intermittently. The amp almost always get wet with harsh winters and kids in the back seat - snow melts off boots and leaks under the front seat and soak the bottom of the amp. I wrapped mine in a plastic bag for this reason. Look from behind the seat underneath, see if the amp has white traces of corrosion near the bottom (usually it has a black paint on it). May try swapping the amp from Ebay to have the radio working

[TrstnBrtt]

I actually didn’t get around to testing it yesterday. I’m going to try to later this evening. It just occurred to me I had to swap out the IAQ sensor on the CCM a few weeks back and I’m wondering if I shorted something with the radio out back then. A few years back the sunroof drain did back up and flooded the passenger side. I honestly can’t remember if the AMP was submerged so we took it apart on Saturday. There was a bit of something on the board but I’m not sure if it was corrosion or not but it didn’t look very significant.

[TrstnBrtt]

Okay, wanted to post an update because I did get some really helpful advice on here but ultimately the battery drain was completely my fault. I’ had replaced my CCM and ICM with the 2007+ updated versions a few years ago. I had to connect the wires coming from the car to a different connector because the existing harness didn’t fit. A few weeks ago when I replaced the air quality sensor in the in the CCM I pulled the harness out of the CD player and the switched power wire broke out of the harness. I repaired it but accidentally routed it to the constant on the same harness. I didn’t put 2 and 2 together until I looked at the wiring harness diagram on all data and discovered it is powered from the Amplifier. Fixed everything up Friday evening and the car sat all night without dying. Measured the battery voltage yesterday and it’s where it’s supposed to be. Lesson learned, and I should not be left alone with butt connectors

[Shogunz37]

I am experiencing a very similar issue with my 2006 XC-90 2.5T. March of 2024, I took into shop due to stuttering crank when starting. Expecting a possible tune-up issue due to being used to older vehicles which crank slow when battery is unhealthy, I was surprised when they said that my battery which wasn't terribly old at the time, they stated that the battery needed replacement. The rest of the warm and fall season was ok until late November when it got cold in Wisconsin. Experiencing the same stuttering crank/start up, I performed a parasitic voltage test by opening all doors and clicking the lock cams on each door including the rear hatch to put the vehicle to "sleep". Disconnected negative cable and check amp draw to post, I saw 20 milli Amps. Removed a hot battery bus phone charger (have to utilize this for my phone since the others are taken up for bluetooth FM xmitter up front and dash cam rear center console). It dropped to 12 milli Amps with the phone charger removed. Acceptable from what I've read is 20 -30 milli Amps on XC-90. Took it into shop about a month ago and they performed a diag and their own parasitic current draw finding the same, within tolerance. As a gesture of good will, they replaced the battery under warranty. FFW a week or two later, it's cold and it's doing the same exact thing. What they did do is ask me what my driving habits are like? I said I don't drive far, maybe a mile total some days to take my daughter to school every day during the week, other days I drive a bit further. Come to find out, that is not long enough for the alternator to charge the battery as most people have at least a 10 min drive one way to and from work/errands. I work from home so I don't drive much anymore. My question is, even after driving it a suitable distance (10 min drive and even putting in lower gear to get the RPM's up for the alternator overcharge to charge battery) I am still experiencing the slow/stuttering start. I've been told that idling, the alternator doesn't really put out overcharge current despite being at 14.5 VDC. If I drive it at freeway speed beyond 15 min, it seems to be ok. Is anyone else experiencing this kind of issue? I am afraid of shutting it off sometimes when it gets real cold unless I've driven it at least 15 min. It seems to happen more when I let it sit outside as opposed to in my garage. I did not experience this issue in prior years when I drove a decent distance, even when leaving it sit in a parking lot for up to a week when I used to do work road trips all the time. I do not know what else to do besides connect a battery tender, but that's a PITA as there's no real quick way of doing it w/o popping the hood and plugging it in every time. That doesn't solve the issue of if I'm parked in a parking lot and I'm not home.