2000 B4000 Problems

Brother in law is having some things going wrong in his truck. When you hit the door lock/unlock switch the horn starts blarring,until you start the truck,it also goes off if you hit the horn.It won't turn off,until you start the truck. He also told me that the cruise control has stopped working. That could be a fuse. If the cruise control fuse was blown would that cause the horn situation? I assume that the truck has an alarm,but he didn't get the keyless entry remote when he purchased it. I was looking to see if I coul dfind the disarm wire for the alarm,but I have looked everywhere,eventhough it says that it's in the drivers kickpanel,I don't see it.I think that the alarm is arming for some reason and if I could find the disarm wire then maybe that would stop the horn problem.Any help apprciated.Thanks:banghead:

Tell him to start by checking all of his ground wires. even the grounds on the tire wells.