Horn was stuck on!!!
 

Hi all, literally signed up today.

Volvo v50 2010,

My horn got stuck on at 5am this morning, absolute nightmare, I disconnected the battery which stopped it and then disconnected the actual horns in the front grill, I then reconnected the battery and now the car won't turn over,

The reason I think the horn was on is due to water dripping through the upper part of the windshield, and either dripping into the steering wheel, also the floor was wet through too.

Wondered if anyone had had a similar issue and if by disconnecting/reconnecting the battery and also totally disconnecting the horns if that temporarily solved the issue? Worried that the CEM will be broke and all of a sudden the Alarm will malfunction and wake the neighbours again, also if anyone knows the fuse for the alarm that would be much appreciated as I'm paranoid it's the next bit of wiring to malfunction

that does sound like typical CEM issue caused by water ingress. Sunroof on your car, by any chance?
Disconnect battery, disconnect CEM, dry&check&clean connections, with some luck its just rusted connectors. fingers crossed
edit - alarm has its own internal battery, but it shouldnt have anything to do with horn itself. If horm was triggered by CEM, thats where problem starts. On the other hand - I am not sure if horn is actually routed trough CEM or there are just relays for it, nut regardless - starting issues and water on the floor = you have a problem and CEM is usually the first victim to fall :/

And what was a problem in the end? Me to had horn blow interesingly also at 5:00 am ...