1996 Volvo 850 Turbo battery problem

For two years now my mother has had repeated problems with the batteries in her Volvo. The battery has been replaced 4 times and a little over two weeks ago the dealer replaced the alternator. This morning the battery was dead again. She has repeatedly asked them to look for the source of the problem that is draining the battery, but they have found nothing.



This morning she went to the car, unlocked it with her remote and got in. When she turned it on the console lights came on and the horn started blowing weakly. When she tried to start the car, she only heard the clicks of the starter.



I read the other post about the security system problem and suspect that my mother’s car may have a similar problem. I have suggested that she have the mechanic check the security system, the door switches, the power panel, and the fuse box for signs of shorts or faulty parts. Is there anything else I should suggest? Does this in fact seem to be the same sort of problem as in the other post?



I am surprised that, if the horn was blowing all night someone in the retirement complex didn’t hear it.

The horn likely wasn’t blowing all night.

I suspected the security system the second I read a weak horn.

There may be a heavy power drain from the security system.

You could do a heavy duty load test on the charging system first though.

You may have to take the vehicle to an auto electrical shop to track this one down.

The mechanic found the problem this time. There was an additional clue to the problem that I had forgotten about. She has also sometimes been having trouble getting the gearshift out of Park.

The problem: The ignition switch. But the mechanic only discovered it when he got in the car inserted the key and, before he turned the key, the console lights came on. The car was not shutting off properly and was affecting both the shift interlock and the security system. So, problem solved… we think.

Thanks for your suggestion and your help.