Ok, I didnt know about this issue until today, since I've been spending the last week going over the mechanicals and just getting this rig ready to start when I turn my key, so I didnt know about it.   plus I had no good battery until today for the aforementioned reason. 

Anyhow, my horn doesnt work at all when you push the button on the steering wheel.     I cant begin to guess why, as I was pressed for time earlier when I realized it, but  the horn just does nothing.   

Also, if I have the dome light switch set to turn the light on when I open either door, it doesnt turn the dome light on.   the light WORKS, but only if I switch i manually to ON.     

I checked the horn/dome fuse in the cabin, and its good, so I dont believe that to be my problem, although I'll have to hit it with a volt meter to confirm it is recieving power.     

Aside from testing wth a voltmeter, what else should I look at to make my horn work, and my dome light?    I've done a little searching, and not come up with much of anything helpful to me.    so I appreciate input.   this is on my 87special edition samurai.

I also have the same problem on my 87, some insight would be very helpful...

I just spent a little while doing some troubleshooting here and learned my horn's contacts were simply in need of a little cleaning.  still hate the OEM horn.  it sounds too much like the one on my old ninja 500.   actually scratch that, the 500's horn was more authoritative.   

In some instances, the horn simply DIES on these things, and being the simple little bugger it is, I understand WHY fullly.   I'll get a photo for the site to help simplify finding it a little.      I"m actually adding a set out of a Dodge Caravan that my friend is dismantling, so I'm getting a free horn upgrade.      This little zuki needs all the help it can get I think to be noticed,  I mean its pretty much a hair frm being a motorcycle as is.

Still havent traced the dome light issue though.     

The dome light has three settings.  Off, on when door is open, and on all the time.  You will need to set it to the center of the three.  There is a censor on the door that when open will allow a ground to be completed and turn the light on.  See if you can find that censor switch, it is probably stuck closed or broken.

As for the horn, I put an air horn on the system from Harbor Freight.  My horn button was shot so a simple push button was installed in the dash instead.

http://www.zukiworld.com/forum/build-diaries-how-to-diy/air-horn-upgrade-for-the-sj/

I have a set of horns out of a dodge caravan, but honestly I dont think they're going to work.  I plugged them in, tried using em nd the fuse blew.     nevermind the fact I have NO IDEA where to mount em.   

at least I learned my AC condensor fan is FUBAR, and no longer turns.  so I've gotta remove that, along with the ac system that doesnt function.

Dont laugh but, I have an AhOOOO-Ga Horn in mine..  The neighbors love it!