S40 won't start, horn blaring, no LED display on dash
 

Drove the S40 to the gym this morning no issues. When I came out, unlocked the car with the remote and went to start. Noticed that the odometer was blank/off, usually its on when the door opens.

The horn started blaring on its own, continuously. The car started. Turned the car off, horn kept blaring. Took the key out and pressed lock, then unlock, doors locked and lights flashed as expected, horn kept blaring.

After a minute, the horn stopped on its own. Tachometer is frozen 1500 rpm, no greed led speedometer or trip meter. Clicking noises from under glove box.

Started the car again and attempted to drive home, but car was sluggish and died after half a mile.

Had it towed home on a flatbed. Put a charger on the batter and it showed 80% and 12.62 volts so I charged it for 3 hours at a 4 amp rate with the battery disconnected. The battery is new Aug 2015.

Now the car starts again, but no led gauges and clicking from the glove box area. With the car running, I put a voltmeter on the battery and it shows 12.2 v, so I'm guessing the alternator is not putting out power.

Any other ideas what could be going on? The car has been dry and in the garage, no recent rain on it.

in some Volvos there's a secondary battery in the alarm system that can go bad but it sounds like you have an alternator or voltage regulator problem. Going under 12.6 volts will create some confusion in the electronics so best to sort out the alternator first. Also double check/clean up your battery cables and ground - if they heat up, that's a sign of a bad connection somewhere.

Thanks for the tips.

I pulled every fuse in the glove box and they are all good. I then disconnected each wiring harness / relay on the fuse board (they were clean) and reseated them.

Now, the car starts and puts out 14.4 volts while idling. All lights, wipers and sunroof work. The horn has not yet blared on its own. I'm not sure if the horn blaring was alarm related, in the past when I've tested the alarm by opening a door from the inside handle while the alarm was set it was a siren sound, not the horn honking.

However, the instrument cluster is totally dead, and I noticed 2 other gremlins. The AC / Radio panel will not stay on 100%, they blink on and off every so often. And the drivers window will not auto roll down or up, although the other 3 windows do auto roll up and down.