Why in the world......
One odd thing, after I started the car with a jump box on the battery in the trunk, a minute or so later the siren started going off. I would get it to go off with the remote, but it would start up again. It would do that if the engine was running or not. Does that indicate anything?




Unknown if this is the case on your car but the alarm siren has an internal battery; when that battery's voltage drops too low due to age, the alarm will sound (but intermittently). Only solution is to remove and or replace. If the siren battery still good, it sounds like the voltage levels in the car are incorrect and the distributed digital control system is producing multiple errors between modules; all sorts of crazy things will happen then.
FWIW, the main battery should be rated at 900 CCA. New, mine tested at 982 CCA with a Solar BA-5. I killed the old battery when I left the parking lights on for several days; never could get the batttery to come back. SAM's had a decent deal on an Autocraft Platinum H8AGM battery for my car for a cost of $160 including tax.
Unknown if this is the case on your car but the alarm siren has an internal battery; when that battery's voltage drops too low due to age, the alarm will sound (but intermittently). Only solution is to remove and or replace. If the siren battery still good, it sounds like the voltage levels in the car are incorrect and the distributed digital control system is producing multiple errors between modules; all sorts of crazy things will happen then.
FWIW, the main battery should be rated at 900 CCA. New, mine tested at 982 CCA with a Solar BA-5. I killed the old battery when I left the parking lights on for several days; never could get the batttery to come back. SAM's had a decent deal on an Autocraft Platinum H8AGM battery for my car for a cost of $160 including tax.
As for the alarm battery, is that rechargeable? Will it recharge itself as I charge the main battery? Or do I need to replace it? I didn't even know I had one - where is it, does anyone have a part number or something for it? I don't know where to start with that.
I've got the battery disconnected from the car while I charge it, tomorrow morning I'll use the Solar BA-5 on it and see where it stands. This all started with a bad front strut, and I haven't even touched that yet!
Here's the problem....now every once in a while the damned siren goes off. Can I just disconnect the darned thing and/or code it out with STAR? I believe it's located inside the wheelwell line on the drivers side. What's better - code it out, disconnect or both?
I have to check the main battery with the Solar checker. I was just eager to get it hooked up and running to see if the suspension issue has been solved - one problem at a time. I seem to have that solved, now on to the battery/siren issue. I presume from reading that the siren has a small battery inside it, and when the main battery dies, that one starts serving to power the siren. When that goes dead, it's done. Can't be recharged or replaced. Is that right?
Thanks,
Doug
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One odd thing I noticed is that the power trunk open/close function doesn;t work anymore. I guess after having the battery disconnected for a whole 2 days it needs to be reset or relearned somehow. I'll have to research how to do that, unless anyone knows off the top of their heads and can post a quick note here. I imagine there are other functions that will be wacky that I haven't noticed yet due to the battery disconnect. I figure it out as I go.
So far so good. Hoping the battery doesn't go dead again.

As for the battery if it turns out bad, Pepboys has the Champion AGM on sale with a $40 rebate so about $118 after the rebate.
Lots of things can cause the battery to go dead, seat control module is one that comes to mind.
That said, there is a very good chance that the relay is fine, but replacing it is very cheap and easy so it's usually better to be safe than risk ruining your battery and/or getting stranded somewhere. Many if not most MB dealers replace the relay when replacing any leaking airmatic components due to the possibility of relay damage: the pump and relay are only designed for intermittent use so excessive use, in the case of a leak, often causes damage (the relay can be continuously actuated without problem, however, it cannot sustain the high current consumption of the compressor for an extended period without damage to the contacts due to heat).



