So as many before me I have a 1999 Volvo S80 T6 where the battery doesn't even last a night.
It does hold a charge if it's un hooked and I'm told it's new and the 2nd battery since it happened.
It charges at 13.8v also.

I havent tried to jiggle the positive wire and see if the charge voltage jumps around yet.
The glove box isn't staying on, the drivers vanity lights turn off (only 1 bulb works) the passenger vanity lights don't come on at all so all burnt out I guess. Without a working bulb it can't suck power I assume.

All other exterior and interior lights are off. Now, the siren I know they mess up. I'm told mine is also, the fuse in the side when I open the door for the siren is pulled. (This is supposed to set off the alarm? No lights flash).
There is another fuse I believe for the siren under the dash behind a cover held with 2 torx screws.

Should I try to remove that one also? If I lose sunroof etc for a while at least I know what's doing it if it stops. And if that's it volvo can simply remove that part of the software right?

Anyone here had the issue and has tracked it down? Is the general concensus that it's the siren gone bad doing it to everyone?

I opened the door with the battery off, pulled some fuses and put them back 1 by 1. It aparently doesn't suck fast enough to do it that way should I do a similar test, pull fuses, let it sit. Check it in morning if it's charged put them in 1 by 1 each time letting it sit over night? Seems legit :P should work right?

I got the car for $800 so if worst comes to worst I can re sell and or dis-connect the battery every night. It does start, and drives fine. Body is immaculate for a 1999. Would love to just find the issue and keep it.

 

Your battery will not tolerate being run down dead very well. It'll go bad in a few cycles of that. So you really need to avoid killing it while you diagnose. I think you should use an ammeter instead, and you can pull the fuses one by one while watching the ammeter. Probably the draw down is 1 or 2 amps, maybe 5, so you need the ammeter to read in that range reliably and of course distinguish 1 from 0.1 which is normal-ish.

 

Ah ok so 0.1-1.0 is normal? I have no idea how many times its been drained, I do know batteries don't like it so from now on I'll be diligent to not have it die anymore. I'll grab that ammeter then thanks for that tip.
So hook it up and pull the fuses right? I will report back thanks

Edit: Ah ok so my multimeter measures ma/a. 20 looks like the lowest setting idk. XD I'll try it out though. Seems alot easier than measurin voltage I doubt I'd ever find it measuring voltage lol. Thanks.
Will probably have results/questions tomorrow.

 

Some little multi-meters can only measure milliamps. The "free" Harbor freight ones will actually measure 10 amps DC, which is pretty handy range for this.

 

Canadian Tire had a dmm on sale for $19 I'm glad I went.
Fuse for the CEM dropped me from 6.5a to 4a, but I can't trick the door into thinking it's closed while it's open on this car it seems. So the CEM may shut off when doors closed, I hear the CEM dims head lights and such when I start the car.

I have 1 un checked relay box I'll do tomorrow because it's under the dash in a hard to get spot.
Then I'm aiming my sights on the siren (which doesn't work and had its fuse pulled when I got the car but there's a relay under the dash for it too I hear).
Then the alternator which I guess something can go bad and drain power.

The battery is in the trunk, if I dis-connect the positive boost post under the hood that should eliminate the alternator from the system? The alternator looks like a real pain to get to and remove the wire directly off it.

 

I am not sure what to make of the CEM, whether it is repairable or not. If you are correct about fuse 32, then I would be looking at a wiring diagram next.

About the alternator, there are so many red links in the battery power distribution, I have no idea how to answer. I would have to just disconnect it at the alternator. That's how I would do it.

Most people don't like to work on electrical problems!

 

Ah I edited my post above then saw yours. So fuse 32 did drop the draw by 2.5a but it's still drawing 4a Unfortunately it must have kept doing it as I had 11v when I went back so it wasn't the problem or not the entire problem.

I'm thinking the CEM showed results since it does so much showed a result but with doors closed it is probably fine, I'd sure like to trick the door into thinking it's closed. They built the damn sensor into the door latch or something.

I have the 1 more relay box and then the only other two things I can think of is the alternator or the siren (which doesn't work and had its fuse pulled when I got the car).
The sirens battery's leak and destroy the circuit board so the fuse + relay under the dash might do it.
I can also just pull it out and toss it in the trash and live without a sun roof which is attached to it I hear, seems odd. The sun roof does work currently with the fuse out for the siren though.

No other fuses or relays did anything besides fuse 32. But still the siren is there not working, the alternator in, and that last relay box I have to check.

I'd like to pull the wire right off the alternator but unfortunately it's in a real bad spot to reach on this car and doesn't look fun. But I might have to suck it up.

Otherwise, maybe as simple as cleaning grounds but the car and them look really really clean.
And then I've hear the positive wire from the trunk to the front can become a resistor when damaged sucking power. The wire seems pretty secure though It will be my last resort.

Who would have thought a volvo would be this bad. I should have read up more.
I now mostly suspect the siren, since it doesn't work and even putting the fuse back in then pulling it didn't set it off as it should have.

The cars clean and nice otherwise, lots of documentation of complaints and zero with a fix. So I'd like to see it threw and document it for others that may come along this.

 

Well it's another day. I was actually able to find some threads of solved issues.

Based on your tip to measure current and the last few things I have left to check I think I'm pretty close to getting it.
I will suck it up and get the alternator out of the equation, I don't want to find out a short cut didn't work and have it be the alternator.
The CEM I'm almost certain either isn't it or isn't the entire issue. I noticed with the doors closed I had a 9a draw and it dropped to 4a now that I think of it after the car went to sleep.
I just forgot the doors open and so it wouldn't sleep.
Odd thing is I had a 6.5a draw later with door open and 4a when I pulled the CEM fuse.

I think I can trick the door by simply closing my door latch while it's still open I read. I will give thst a shot since it makes sense.
But when I looked at it, it looks to me like the switch is actually in the arm that holds the door open, were the door and car meet by the hinges.

I will make sure to post what it is if I find out, and if not I'll post a pic of the car on fire for you guys. Haha I wouldn't burn it she's to pretty but she sure likes to make me work hard .

 

volvowiringdiagrams.com is a good resource. When you say pulling fuse 32 you dropped by 2.5a, do you really mean 2.5ma? note fuse 32 also does vanity lights (glovebox, dome, mirrors etc) which if left on can drain a battery over the course of a day or two. There are also a set of fuses in the trunk - did you test for draw on those as well?

 

Some wiring diagrams may be very helpful if I need them thanks.

Yes I tested the fuse box under the hood, inside the car on the side of the dash and also in the trunk on drivers side behind the carpet.
And I looked at all the lights, none stay on.
Also I haven't been arming the alarm so I don't think it's been going off randomly.

Battery is able to hold 12.6v and alternator charges at 13.8v cold.
My cavalier will charge 14.2-14.4 cold but drops to 13.8 at operating temp.
And the cavalier has a older alternator. Isn't 14.2 - 14.4 supposed to be constant on a new alternator?

I have 3 things to do still.
#1 is now the alternator.
#2 there's that relay box under the dash, you use 2 torx bits to take the cover off and then you hire a contortionist to squeeze up there and pull them. In all seriousness though it is a hard to get to spot so I didn't do it yet.
#3 the alarm siren, the fuse is already pulled however I put it back in and behold lights flash and such but as with most the siren did nothing. There should be a relay for each fuse, meaning that damned box under the dash should have a relay to my siren. If I pull that too along with the fuse that should eliminate the siren as a culprit. Or I can pull the passenger wheel off and take it out, volvo wants an arm and a leg for that siren new...

It's raining and cold out today so I won't be doin anything on the car as I have no access to a garage.

Edit add: I have seen that volvo has claimed "Quote: The battery B+ cable has problems with the terminal end necessitating replacement.
Symptoms may include no start, warning lights coming on and other odd electrical issues.
The B+ cable end is located in the engine compartment fuse box near the drivers side shock tower."

So in light of that I now have a #4 item to look at and I may as well test grounds while I'm at it or just clean them anyways since it's a 1999 and could probably benefit from it regardless.

So I am supposed to have a 0.1 to 1a draw? And I have 4-4.1 right now with everything sleeping.

And I'm not a genius but I have the dmm on the 20 for dc a. So I assume 4.1 is full A?

 

I think 4 amps makes sense for a car with the battery going dead in less than 24 hours. I believe it. It's kind of a large draw. 4 amps with 12 volts is 48 watts, so that should be generating considerable heat if it's not moving anything. If it is all going through one device that device would be warm. The alternator is one place where a large power draw can go without the heat being obvious.

I forgot to mention the easy stuff when I responded at first. When the battery is doing down, it's probably best to look at the car when it's dark outside and see if you have any lights on. You have to either check somehow or remove the glove compartment light. Nowadays you can set your phone taking video and put in the glove box to see if the light goes out. The glove box light would not pull 4 amps though.

 

This rain and weather is killing me, they're calling for snow later today.
Anyways tomorrow is +11 ill work on it, might as well try looking for lights though tonight.

I can slowly close the glove box and watch the light go out. That doesn't mean it doesn't end up back on though, I didn't but should touch it to see.
Also the visors are visible if you look the drivers shuts off the passenger one is burnt out.
Dome lights seem fine, under the mirror lights seem fine.
I pulled the trunk lights out to do the testing and so its fine.

I do have lights on my doors were when you close it they become hidden between the door and car. They appear to turn off, however it was daytime and hard to tell.
There's 4 of them so maybe a couple are on.
But I looked carefully while opening and closing and to me it appears the lights are off. I can see their reflection on the cars body as I slowly open/close the door.

I can probably reach the alternator and touch it.
That's a good idea, the positive cable has had reports of needing replacement and also heating up due to resistance.
The car was from 12.6v to 11v and visibly dropping by the time I drank 4 beer... The cable didn't appear noticeably hot however it was a warm day out.

As for the alarm siren I need to get a rivet gun and some rivets. Take the passenger tire off, drill out rivels and a security screw to remove it. But it doesn't even work and that makes me suspicious from what I read about them. And like I said, its fuse was pulled before I got the car.
But there's probably a relay or some form of direct power since its an alarm and it would be all to simple for a thief to just pull a fuse and drive away. I did for experimental purposes put the siren fuse back in. It didn't change anything.

I could see the alarm siren being it's own wire with an in line fuse hidden. Just because it's for the alarm. It shouldn't be easily disabled.

Shouldn't an alternator be 14.2v - 14.4v constant? (A brand new strong one.)
My 2001 cavalier alternator charges 14.4v on a cold start. Once it's warm it drops to 13.8v
I know this from my display I have for the aftermarket stereo. The alternator is less efficient when hot.

So if 13.8v is the starting charge on my 1999 volvo I feel if it's not broken it's ready to give up soon. Going to pull it and see if it's the problem. And if not I'm still replacing it.

Edit add: So 13.8 - 14.2 is needed to properly charge a battery.
I know rpm affects charge voltage, and on a cold start the rpm is higher and thus the alternator turns faster. Both cars I started cold on the same day and the cavalier started at 14.4 the volvo 13.8 so once they warm both drop.

0.6 on the cavalier, so the volvo should be around 13.2 warm. Not good I don't think. I expect it to keep 13.8 atleast and feel that's still low.

 

The wiring diagram is a bit confusing. I have to keep looking at the abbreviations but I suppose its necessary. I don't need one yet anyways. I thought it might help me understand how the B+ cable goes up to the engine but not really.
It shows it goes up and to parts. But from what I know the fuse box is on the left of my B+ and the diagram draws to the right side. So location isn't depicted well unless you understand the abbreviations and realise. I guess it helps some.

Makes my head hurt. Fingers crossed today she's fixed.


Found this today (while I should have been working) I will take it with a grain of salt but ill look at the siren last now.

Quote: "If the small battery in the siren unit is going bad, then reports are that this will drain the main vehicle battery even when the ignition is off. That would account for your low main battery.

The siren unit in my 2004 v70 failed a couple of years ago, and since then I have gotten the alarm service message when I first start the vehicle. As soon as I realized this was the case I pulled fuse #38 ('alarm') in the fuse block at the end of the dash (left side on my LHD, so presumably right side on your RHD)under the belief that removal of this fuse prevents the siren battery from draining the main battery. I had no low battery problems with the fuse pulled.

I had the vehicle into the dealer shop for service and wanted them to look at the siren and so I reinserted fuse #38, but they didn't have time or inclination to deal with the alarm. I left fuse 38 in place and later when I didn't drive the vehicle for a day or two the battery was so far down that it wouldn't operate the starter.

I charged the battery (in place in the vehicle) and removed fuse 38 and I have not had a recurrence of the low battery condition even when I haven't driven the car for a day or two.

When I lock the vehicle with the remote the red LED on the dash flashes as if the alarm were active. I am still on the original main battery after 7 years of service and 50,000 miles."

 

I hope that fixes it. The 13.2 volts seems a little low, but the alternator is of course working. With the engine off voltage will typically be 12.5. So we shall see, I guess.

 

Ok so under the hood. What I thought was 2 grounds are positive wires.
Even though they're black... Why would they use black positive wires I don't know, is that normal on Volvo's?
Anyways I removed both, it pulled 0.11a
Put the one for the alternator and starter on, it goes to the starter and then alternator. It pulled 4.03a
Took it off, put the one to the fuse box on. It's slept down to 1.81a
That wire to the fuse box does have some green corrosion and it's short so replacing it seems like a good idea.

I removed the alternator connection that continues off the starters, and the draw was 1.81a
I'm going to clean the engine ground and starter ground. I think the alternator grounds to the engine, starter too maybe.

Edit add: ok nevermind about 1.81
It's now 0.09
So its starter or alternator.

4.03a below, only thing wired under the hood is the alternator and starter. The wire goes to the starter, then the alternator. (the fuse box has no power under the hood. some other components may elsewhere)



1.81a alternator and starter are not connected anymore. But the front engine bay fuse box is now.



0.09a I guess she went to sleep now. This seems acceptable? This is with the front fuse box connected still after some time waiting around.


Red Positive wire comes from the battery in the trunk, up to the front. Where it has a post as its end. Two black wires are on the post held with a bolt. The one short one goes to the fuse box, the other to the starter, then the alternator.




Here we see the wire I am talking about where It goes to the starter, then you can see the red wire that comes off the same connection goes up to the alternator.




I found a place that may sell me a used alternator for $175 + sales tax and shipping. I asked them to test it first. If it fails $380 new.

I'll continue threw till the end after the alternator is replaced, might help someone out. Thanks a ton firebird your awesome. I see not many like to bother with electrical, I can tell why.
Now lets hope once I get to the alternator there isn't any other wires down the line that go somewhere else. Perhaps a direct positive with in line fuse off that to the alarm siren. Which as mentioned doesn't work.
I guess we will find out wont we.

 

How did this end up? I am going through something very similar. 6.5a draw just starting the fuse pulling process.

 

Well as I mentioned it's the alternator that's drawing the power for me.
When you first put the DMM on the car electronics wake up, give it a minute or so to sleep it should drop from 6A to about 4A.
If it doesn't then you have a even bigger draw than mine and you may have two or more issues.

I'm in the process of removing my intake manifold right now to replace the alternator.
4A is a huge draw, 6A is wow. I would think once the electronics sleep after a minute of connecting the DMM inline that you will drop 1.8-2a down to 4A. Like me.

 

Thanks for the great write up and pics, I have an S80 with a 4.7 amp draw., because of you're write up going to check the alternator first and probably fuse number 32. Definitely want to get this tracked down as it drains the battery quickly.