My 2006 la coss CX went crazy . Head lamps, horn, wipers and water shield washer work like crazy until battery dies .
It happened several time , both horns are burnt .
changed battery , changed both computers (body and engine ) did not help
now it even worse if I connect a battery to the terminals all these things happen , but car wont start . no reading at the body computer port . any one can help ? Thanks Mates
car is normally well maintained, 140000 miles ,

• Buick
• Buick LaCrosse
• 2006

Maybe water in the fuse/relay box(es)?

I'd start by removing all of the fuses and relays completely (document thoroughly) and then reconnect the battery and see if the problem is still there. If it isn't, then you can add fuses and relays one by one and see which ones cause trouble. If it is still there, then it'* a short between the fuse box and battery somehow crossing some amount of other wires.

Did it recently experience any trauma? Flood, heavy rain, accident, major repair, etc?

thanks
will try . no traumas as such

Won't start? Cranks over, but doesn't start or doesn't crank over?

Have you checked charging system? If ok, checked for a draw?

Scanned for codes, especially "P" and " B" codes?

thanks .
Does not crank when in the crazy mode (which is now permamanent . no reading on computer at all! no Juice ...

OK, make sure battery is ok.......then check all fuses with a test light for power....