'92 Safari horn, doorlocks and speedometer problem. Need help please.

I started having this problem with my Safari yesterday. About a minute after leaving my driveway the horn gives 3 or 4 short beeps on its own. When it does this, the speedometer fluctuates up. Immediatly
following the horn acting up, the power door locks attempt to lock (if they are unlocked then they will lock, if they are already locked then they just click as power is applied). This will continue to repeat every few seconds. Yesterday, when it started, I pulled over as soon as it was safe and restarted the engine and had no problem for the next two short trips (3 or 4 miles). Later in the day I left the house with it and everything seemed fine. I got to the local school zone and looked at the speedometer and it showed 80 (I was doing about 20). The speedometer jumped all over the place and about 30 seconds later here comes the beeping. Anyone have an idea where all these systems might merge together and maybe short out. Since it doesnt do it all the time I have no idea where to start looking. I wrote this 4 days ago. Been having problems posting. Anyway, the van hasn't acted up in the last 2 days. Any idea what caused this would be appreciated. Thanx a lot.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bill wrote:

Some of the symptoms seem like it is going into security lockdown mode. But the speedometer is different. If you had huge surges in the electrical system, that could explain a lot of things. You might try scanning for diagnostic codes, but there may be none. You might have to scan it right in the act. It is for reasons such as this that I keep my scanner inside my car at all times, and I could leave it hooked up at all times if I had to.
You might have somebody poke around the electrical system, maybe around the alternator, just to see if everything tests normal there.
---Bob Gross---
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
you have a short some where
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.