So my '09 JKU has developed an electrical gremlin after 15+ years of good service.

• In late August, I noticed the horn stopped working. Checked the fuse several times; don't know where else to look.
• A few weeks ago the front right turn signal went rapid, indicating a bad bulb. No biggie, but when I checked the filament, all good.

Checking further: I get the rapid indicator only when the lights are on, the signal light works in daylight driving. Thinking the bulb may have failed with a good filament; new bulb. Still not working properly. All other lights and signals are good.

Any suggestions will be greatly appreciated!
TYIA, Steve

 

In the 18 years I've owned my JK, electrical problems have always been due to bad grounds.
Regarding the horn, have someone push the horn button while you listen at the fuse box. You should hear the relay's very faint click.
If you hear the relay, check the ground wire at the horn for continuity from the connector to a ground point somewhere under the hood.

The turn signal behavior sounds like a bad ground connection. The connection can carry either the running light, or the turn signal, but not both. It could also be a loose connection of the bulb in the socket.
Check for continuity from the light fixture's ground wire to a point under the hood.

A bad ground wire is easily fixed by running a new wire. The old wire probably disappears into a bundle, so it's hard to trace.