SOLVED 04 XC90 another parasitic draw

Thank you for the help!! I figured the low voltage caused the craziness of the electronics. I thought that .19ma was low as well for it to drain a brand new battery over 5 days of short trips and sitting over the weekend. I read a post where the alternator was "caught red handed" after driving 45min and then testing the car for draws. I'm starting to suspect my alternator diodes. However, I am also suspecting my SCM because my siren doesn't work at all and I was getting the dash message (would go away after resetting and has been off since battery has been recharged). I also noticed upon getting the car back from getting new keys that the car alarm had been set off randomly as it sat with no sound but flashing lights and would go off after hitting the key fob buttons. Would the SCM draw enough power to kill my battery as described earlier? Everything else works, sunroof, etc. I should also note that I can only unlock the doors from inside if I open my drivers door and hit the button or simply use the key fob. Is that normal? Tomorrow I will test again with some help.

I personally think you're basically doing just that at the moment as you "guess" why your vehicle is acting oddly in multiple directions without having all of the error messages in hand.

I had asked about the battery for a reason, is it original? Volvo part with a WWYY stamped on the negative terminal if yes. If your battery is original, replacement is the first thing I would do.

Siren is highly likely failed due to an internal NiCad battery leak, the module just needs replaced.

Both alternator and battery can be tested by any content shop and some auto stores, often for free. No need to guess there...

You mentioned having keys made, the folks who did it never provided you with all the codes the vehicle is producing? If they did, please post and I'm sure it'll help pinpoint the problem(s) and give you a place to start.

Last but not least, you read up on the known T6 issues before you bought the vehicle so you are aware what you have transmission-wise, right?

I'll keep an eye on this one and see if I can assist as you move forward but codes are a must in my opinion (after answering the battery question).

Battery is brand new gold series from autozone, dates 08/21. I have a document from the dealership for the inspection that I took a photo of, pardon the quality. There's are no check engine light currently on my car. Currently, only messages on dash are bulb position sensor, anti skid service. The ABS light is on the dash. Occasionally the brake assist will come on as well as the alarm system needing service.

Alright here's an update. Tested the car again today and now I'm baffled. I did this twice too. Reconnected the battery, let the car warm up and shut her off. Opened up the hood, trunk and driver door and closed the latches and the car went to sleep. Waited 15min, then carefully hooked up my meter and slid the ground off the battery. Read .002A. I may buy another meter... I then proceeded to pull every single fuse and relay in the trunk, driver's panel, and under the hood. No changes at all. I did that twice. So now I've got a random draw that is sneaky. I decided to investigate around the scm area, looks like someone may have been in there before. I didn't pull the tire but the rivets on the wheel well were drilled out. If they replaced the scm I'd have my alarm sound back correct? I also did some testing on my alternator which was interesting. Not sure if this is normal:
Alt charge cold idle 14.38-14.49
14.40ish warmed up at idle, max and min readings were 14.1 jumped to 15 (voltage went down to 14.1 then jumped to 15 and then evened out around 14.4 again). I tried to do that ACV test and here's what I got: ACV . ~.02-.03 bouncing and occasional jump to .1v don't know if that indicates anything about my alternator diodes. Anybody got a guess or a direction to go next? Posted some pics, that's my wife's hands FYI definitely not mine 😂 also if I'm using my meter wrong please roast me

Dust101496 said:

Alright here's an update. Tested the car again today and now I'm baffled. I did this twice too. Reconnected the battery, let the car warm up and shut her off. Opened up the hood, trunk and driver door and closed the latches and the car went to sleep. Waited 15min, then carefully hooked up my meter and slid the ground off the battery. Read .002A. I may buy another meter... I then proceeded to pull every single fuse and relay in the trunk, driver's panel, and under the hood. No changes at all. I did that twice. So now I've got a random draw that is sneaky. I decided to investigate around the scm area, looks like someone may have been in there before. I didn't pull the tire but the rivets on the wheel well were drilled out. If they replaced the scm I'd have my alarm sound back correct? I also did some testing on my alternator which was interesting. Not sure if this is normal:
Alt charge cold idle 14.38-14.49
14.40ish warmed up at idle, max and min readings were 14.1 jumped to 15 (voltage went down to 14.1 then jumped to 15 and then evened out around 14.4 again). I tried to do that ACV test and here's what I got: ACV . ~.02-.03 bouncing and occasional jump to .1v don't know if that indicates anything about my alternator diodes. Anybody got a guess or a direction to go next? Posted some pics, that's my wife's hands FYI definitely not mine 😂 also if I'm using my meter wrong please roast me View attachment 134946 View attachment 134947

Click to expand...

The upper picture shows the meter selected for small battery testing, but seems to be showing DCV. The dial should be turned to DCV, if you are trying for that. The way it is connected could result in the meter popping a fuse, or frying the meter if the headlights or starter were engaged, as the meter is in series with the battery and the load.. To simply measure battery voltage, touch the red lead to the positive terminal and the black lead to negative when DCV is selected and the leads are in the appropriate sockets. There may be a difference in the readings using the other modes.
The meter isn't hooked up quite right in the lower pic. The dial is set to DC 10A, but the red lead is not in the correct socket for that function. The meter seems to be reading mA values, and the red lead is in the correct socket for that function, although not selected by the dial. I wouldn't take it for granted, though. Generally, the extra 10A socket will be for a fuse protected connection. It could be that if the meter is switched to the mA detent, the reading will be the same, except for the decimal places will be moved over.
I looked for a manual for that meter to explore the finer points, but no joy.
It may be a good idea to do a little refresher on using that multimeter. There are many videos available:
Some may have misinformation, so beware, and skim the comments.
There's a thread here somewhere about a poster doing a current draw test, and it covered all the bases well. The big problem is that there has to be enough voltage and current available to lock the car. Accomplishing that is harder than it sounds because all the doors and hatches must be closed and the locks triggered with the remote. Only then will the system go to sleep with one eye open. That may be more current than the multimeter can handle, as all the lights and locks are powered simultaneously when that happens. A possible method would be to string heavier wiring with a switch in it to an open rear window, and the meter wired in parallel to the bypass so that it will read what happens when the baby is put to bed.
I hope this doesn't come across as a "roast", as I still think "every day is a school day" in my senior years. I look forward to new lessons every day!

The tests you are trying to do are difficult to accomplish correctly. The easiest way is to go to the parts store and buy a battery disconnect switch. Wire it between the battery negative terminal and the negative cable. When the switch is closed the car will operate normally.

Then, configure the meter to measure amps. Probably a good idea to start at 10 amps, which, as Captdirk pointed out, requires the red probe be in the dedicated 10A connector. Connect the plus meter probe to the side of the switch attached to the battery cable and the negative to the battery terminal side. Use jumpers with alligator clips so things don't fall apart.

Open the switch and read the draw. Close the switch and reconfigure the meter for the next lower current range (move the red probe back to the normal position.) Open the switch and read the draw. Keep lowering the range until you get a reading that would exceed the next lower range. If you interrupt the circuit by removing the battery cable or opening the switch while the meter is not there to provide a path, you will wake up the electronics.

While the switch is open, be sure you don't do anything that would cause a draw greater than the range of the meter. (Looking at your meter it appears you have only two ranges, 10A and mA. Look at the meter's documentation to see what the limit is for the mA range. Stick to the 10A range until you are certain the draw is in the mA range or you risk damaging the meter.) You can switch the meter configuration while the switch is closed without waking up the electronics. Anything that wakes the car up will probably exceed the 10 amp limit, so, secure the car before you open the switch.

With this setup, you can watch the car go to sleep over a 15-20 minute period. It should settle in to a draw in the range of 20 to 60 mA. At that rate, the battery should last a month or so.

Sorry for the delay, didn't get as much done this weekend. Went and bought a nice fluke meter. Haven't used it yet tho. Replaced a bunch of bulbs, got a better battery charger, and replaced a wheel bearing. Still need to swap another bearing and also fix the rear windshield wiper. I charged up the battery again and after hooking it back up with the switch and all I found that I had a .77A draw with the alarm set, and a .74A draw with it off. These were both taken well after the 15min mark to get the car to sleep. So now I have to go around yanking fuses again. Side note, I discovered that a larger square relay in the cargo fuse panel makes a buzzing sound typically when the car wakes up...what could be causing that? I replaced it, new one does it too but not as much.