Horn Repair.
Like any inactive old car many of electrical system was not functioning when I got the car. Horn was a one of them.
Karmann Ghia uses a relay for the horn. Basic set up is this. Power is coming from fuse block to the relay. From the relay one wire goes to the horns. Other wire goes to the switch on the steering wheel.
Trouble Shooting.
• Check the fuse, and power at the relay.
• Remove the brown wire, which goes to the switch, and check for the continuity to the ground and the function of the switch. Good system should show open circuit at normal, and closed circuit when you push the switch. Well, Mine was good.
• Attatch the voltmeter at horn's input side terminal and push the horn switch. My voltmeter showed 12V. The relay is good.
• Check the continuity across the two horn terminals. Good unit should show small resistance. (Typically less than 10 ohms) Mine had open circuit on both of them.
Horn Repair.
 Horn is basically a spring-loaded electro-magnetic switch. Power is applied to the electro-magnet through the internal switch. Once electric-magnet energizes it open the switch, cutting the power to the electro-magnet, then spring close the switch and repeat the process again.
• Remove it from the car.
• Disassemble by removing the small screws all the way around, open the cover, and remove the diaphragm. Note the direction of the diaphragm. 
• You will see the switch inside, so check the condition of the point visually. Mine had oxidized layer on the point.
• Remove the point. You may have to break the seal outside of horn housing to do it.
• Clean the point with file or sand paper. I used needle file and #400 sand paper.
• Re-install the point and check the continuity of the point. You may have to adjust the spring loading screw.
 • Re-assemble the horn. I cleaned and painted while it was disassembled.
• Test it with a power supply. (I use a small battery charger.)
• Install. |
